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  1. Thank you for the guest appearance.

    You look at various temperature histories and assert that something has happened, and that thing has some persistence.

    While I don’t see much gain in analysing every last wiggle, a claim of a 10-some year excursion from the mean would seem to require some preliminary physical explanation. What is happening? Is there some observable change in ocean or atmospheric circulation, some redistribution of heat, some feedback effect that then changes the radiative balance?

    While the 1998 El Nino was certainly strong, I will need more convincing that the aftermath reflects an ‘episode’ that is outside the usual variability.

    [Response: On a general note, my thanks to everybody for all their thoughtful comments. Kyle himself is out of town at the moment but we decided it was time to go ahead and post this anyway while the paper was still fairly fresh off the presses. I will do my best to provide some feedback to the comments in Kyle's absence. (I am pleased to say, by the way, that Kyle was my first grad student at U. of Chicago). As for this comment itself, yes indeed it is hard to do decadal variability with a relatively short record, but given that there is a need to try to sort these things out without waiting until CO2 has already doubled,one must simply do the best one can with the available data and hope the picture becomes clearer as time progresses. --raypierre]

    Comment by tharanga — 12 Jul 2009 @ 4:51 PM

  2. > more convincing

    later papers citing the above-cited paper on wavelet analysis:

    http://ams.allenpress.com/perlserv/?request=forward-links&doi=10.1175%2F1087-3562%282000%29004%3C0001%3AITEASI%3E2.3.CO%3B2

    Comment by Hank Roberts — 12 Jul 2009 @ 4:58 PM

  3. Thank you Mr. Swanson for that thoughtful and fair–balanced analysis.

    Comment by Jacob Mack — 12 Jul 2009 @ 5:15 PM

  4. Maybe this annomaly you speak of has something todo with the montreal protocol?
    http://en.m.wikipedia.org/wiki/File:Ozone_cfc_trends.png

    Comment by save gaia — 12 Jul 2009 @ 5:27 PM

  5. Raypierre, its completely counter intuitive to suggest that there will be a pause in Global Temperature warming. Unless there is a change in long term weather, world wide, in a sustained fashion, which is possible but a rare event. What I see recently is yearly variations caused by regional weather scenarios. In the case of this summer, to make it familiar, the NE North American Coast and most of Canada is cooler by extensive periods of cloud coverage, cooling caused by this region clashes with the US South extreme heat, given less bouts of clouds up North, the North American warming record would have been amazingly strong, but permanent cloud episodes over one region or another travel, never last forever, as such not causing a permanent shift in the temperature record (unless the clouds cover or not wide swats of the Polar regions). Conversely, one side of the Hemisphere may be cloudy , but the other not so. Despite NAO and El-Nino periods. The over all recent result, the world wide average in temperature, has increased. I would suggest comparing peak to peak average temperature captures during weighted El-Nino events (during the time they occur, if they can be compared equally this would be a telling graph), instead of considering year to year records as a means of reducing ENSO effects on the temperature record, ENSO being largely a heat exchange between air and sea causing great changes in cloud distribution world wide.

    Time will show that the proposed pause in temperature increase is a model artifact… I doubt very much in such an occurrence.

    [Response: Wayne, please note that this is Kyle's article not mine, though I did encourage him to write it for us. I think the interesting question raised (though not definitively answered) by this line of work is the extent to which some of the pause in warming mid-century might have been more due to decadal ocean variability rather than aerosols than is commonly thought. If that is the case, then a pause or temporary reduction in warming rate could recur even if aerosols are unchanged. Learning how to detect and interpret such things is important, lest a temporary pause be confused with evidence for low climate sensitivity. --raypierre]

    Comment by wayne davidson — 12 Jul 2009 @ 6:46 PM

  6. This observation look very much like the so called “Magic Door¨. This looks like a jump from one state of a cahotic attractor to another.

    Comment by Yvan Dutil — 12 Jul 2009 @ 7:44 PM

  7. Is there any connection to the AMO?

    Comment by Patrick 027 — 12 Jul 2009 @ 7:54 PM

  8. Are the episodes thought to be actual changes in the amount of heat being radiated by the planet (because the surface of the ocean gets warmer and cooler, does the actual infrared flux from the top of the atmosphere then change as a result)?

    If so do we have any baseline satellite record that can be watched assuming we do get another El Nino this fall and winter?

    (And would Triana do anything useful, if put up and operating?)

    Or are the episodes thought to be changes in where the heat is being carried in the atmosphere/ocean system,

    [Response: In the end, these episodes should be primarily thought of as fluctuations in the atmosphere/ocean heat exchange. Think of what would happen if you could pump cold deep water up to the surface, increasing the air/sea temperature gradient and warming the water; that would give you an anomalously large ocean heat uptake. Some of that would result also in a change in the radiation to space, and in particular a change in the net top of atmosphere radiative imbalance. Cloud feedbacks and water vapor feedbacks would affect the translation into TOA imbalance. In any event, such imbalances are at present exceedingly hard to monitor by satellite. --raypierre]

    Comment by Hank Roberts — 12 Jul 2009 @ 8:14 PM

  9. Raypierre, its completely counter intuitive to suggest that there will be a pause in Global Temperature warming.

    Note: It’s not Raypierre’s post, it’s by Kyle Swanson of “Swanson & Tsonis, 2009″.

    Comment by dhogaza — 12 Jul 2009 @ 8:16 PM

  10. Is a linear trend line justified in the first graph? All the forcings seem to be accelerating.

    Comment by Greg Simpson — 12 Jul 2009 @ 8:20 PM

  11. How do I answer the sceptics/deniers who utilise the cooling since 1998, matched with the trend lines in the IPCC reports that show warming climbing while the reality is cooling or at least flat lining?
    (Ergo the IPCC is a crock and therefore every thing relating to AGW is also a crock?)
    Here in Australia the deniers loaded this question onto Senator Steve Fielding, fresh back from the USA on a “fact finding mission” to the Heartland Institute, Sen Fielding then used his vote in the Senate to block the ETS bill.
    If El Nino is put up as the reason why doesn’t the the forecast’s take that into account and show it???

    Comment by Jim Thomson — 12 Jul 2009 @ 8:41 PM

  12. Dr. Swanson: One distinction between your analysis and the more conventional ones is the rate of underlying warming that is occurring due to radiative forcings. I notice that your fit to the temperature data from 1979 to 1997 gives a slope very close to 0.10 C / decade, whereas I believe a fit over a longer period (like 1979 to 2008) would give a slope more like 0.16 C / decade. Do you believe that the 0.10 C / decade value is a better estimate of the current forced response to the net radiative forcings on the climate system?

    Comment by Joel Shore — 12 Jul 2009 @ 8:41 PM

  13. Is the red line schematic, or is there some objective way in which its level is determined? The time at which there is a ‘return to warming’ is somewhat sensitive to this value, right?

    Comment by Pat Cassen — 12 Jul 2009 @ 8:59 PM

  14. >>> slope very close to 0.10 C / decade,

    Look at the figure again. Looks to me like linear fit goes from -0.3 to +0.55 degrees in 50 years, or 0.17 degrees per decade.

    Comment by Brian Brademeyer — 12 Jul 2009 @ 9:23 PM

  15. Another important paper of recent is by Easterling and Wehner that demonstrates that cooling on timescales of years to a decade or two are not that unusual even when the system is undergoing a long-term warming trend induced by radiative forcing.
    http://www.agu.org/pubs/crossref/2009/2009GL037810.shtml

    I’d also like to extend thanks to Dr. Swanson for discussing his paper, which I believe certainly contains some “different” perspectives, and has also been cited inappropriately on the internets. Unfortunately it isn’t a perspective I would give a lot of predictive power to (and is somewhat too reliant on a particular dataset) but as noted in the post, only time will tell.

    Comment by Chris Colose — 12 Jul 2009 @ 9:35 PM

  16. Re Jim 11: I don’t think there has been any cooling, nor any “flat-lining” on time scales relevant to present climate change. See http://www.realclimate.org/index.php/archives/2008/01/uncertainty-noise-and-the-art-of-model-data-comparison/, among others here.

    The trajectory of the forced climate change is a subtle one; fluctuations due to El Nino and other oscillations (“weather”) have a high amplitude and will obscure the long-term trend if you look at short time scales. And yes, short can be 10 years. 1998 was a outlier warm year due to El Nino. Last year featured a La Nina. Cherry-picking 1998 as a starting point and forcing a linear fit through the noisy data of 10 years since then has little meaning.

    The models also produce their own such weather noise. It’s just that the noise within the models is not correlated in time with the real noise; getting that right would be like predicting the weather several years out. That is not the purpose. Their purpose is to get the longer term trends. Observations since 1998 are still within the model projection bounds, see http://www.realclimate.org/index.php/archives/2008/04/model-data-comparison-lesson-2/

    I suggest you download the GISS Temp data and see for yourself how noisy the data are. Choose some random ten year periods, zoom in on them, and you’ll not always discern the longer trend. Then zoom out to a view of 40+ years, and you’ll see the trend pop out from the noise. Save some plots, and show them to your sceptic friends.

    If I follow him, the author here is suggesting that recently there has been some longer-term coherence to the noise, in a sense – that the repercussions of that El Nino are still being felt, that we’ve been warmer than the mean trend since 1998, and that we’re only now coming back to the trend mean. I am unconvinced, but this post is already too long.

    Comment by tharanga — 12 Jul 2009 @ 9:37 PM

  17. If the ’97-’98 change is “better than 3 standard deviations of interannual variability” as you state, might that not simply indicate that the interannual variability is not normally distributed? Eyeballing the graph, it looks to me like changes of similar magnitude have occured downwards a half dozen times since 1900 and upwards perhaps 4. Would the actual year by year data put the lie to this eyeballing (perhaps some segments that look to me like one year might be two or three with near-matching slopes)?

    Great blog, keep up the good work.

    Comment by Douglas McClean — 12 Jul 2009 @ 9:41 PM

  18. Hank Roberts wrote in 8:

    If so do we have any baseline satellite record that can be watched assuming we do get another El Nino this fall and winter?

    Hank, presumably it is official at this point.

    Please see:

    NOAA scientists today announced the arrival of El Niño, a climate phenomenon with a significant influence on global weather, ocean conditions and marine fisheries. El Niño, the periodic warming of central and eastern tropical Pacific waters, occurs on average every two to five years and typically lasts about 12 months.

    NOAA expects this El Niño to continue developing during the next several months, with further strengthening possible. The event is expected to last through winter 2009-10.

    El Niño Arrives; Expected to Persist through Winter 2009-10
    July 9, 2009
    http://www.noaanews.noaa.gov/stories2009/20090709_elnino.htm

    But I would have to check to see whether this squares with the official definition.

    Please see:

    North America’s operational definitions for El Niño and La Niña, based on the index, are:

    El Niño: A phenomenon in the equatorial Pacific Ocean characterized by a positive sea surface temperature departure from normal (for the 1971-2000 base period) in the Niño 3.4 region greater than or equal in magnitude to 0.5 degrees C (0.9 degrees Fahrenheit), averaged over three consecutive months.

    North American Countries Reach Consensus on El Niño Definition
    http://www.nws.noaa.gov/ost/climate/STIP/ElNinoDef.htm

    As for what the models predict (as of 17 June 2009), you can see it here…

    Summary of ENSO Model Forecasts
    17 June 2009
    http://iri.columbia.edu/climate/ENSO/currentinfo/SST_table.html

    … but things can change in a month’s time, and while the current El Niño is expected to last through Fall and Winter (and in fact roughly a year if it is typical), the previous one (early 2007, I believe) burned itself out unexpectedly and we fell back into a La Niña.

    Comment by Timothy Chase — 12 Jul 2009 @ 10:01 PM

  19. Has anybody tried to draw a connection between this work and the Keenlyside paper, which I believe used SST values for initialisation and predicted no warming for a while? Is there any plausible connection?

    [Response: I think the connection is very intimate. We at RC think that some of the Keenlyside results "predicting" an interruption of warming were overstated and misinterpreted, but for me personally the take-away message from Keenlyside is that ocean dynamics is capable of producing a temporary warming interruption, even in the face of growing radiative forcing. --raypierre]

    Also, what happens to the plots above if some other temp set is used, instead of Hadcru? I do wonder if we’re seeing artifacts of the chosen data set, particularly the one with selective exclusion of grid boxes.

    Comment by tharanga — 12 Jul 2009 @ 10:08 PM

  20. Dr. Swanson: Another question – This prediction of a pause in the warming seems somewhat similar to the prediction of Keenlyside et al., although, as I understand it, theirs is based simply on a direct model prediction (with an attempt, whether successful or not, to use realistic initial conditions in initializing their model). Is it possible that they could be detecting in their model the sort of shift that you believe may have occurred…or do you think that the fact that they and you make a similar prediction may just be coincidence?

    Comment by Joel Shore — 12 Jul 2009 @ 10:13 PM

  21. Brian Brademeyer (#14) says: “Look at the figure again. Looks to me like linear fit goes from -0.3 to +0.55 degrees in 50 years, or 0.17 degrees per decade.”

    No, that’s from 1950 to 2030, which is a period of 80 years.

    Comment by Joel Shore — 12 Jul 2009 @ 10:17 PM

  22. Thanks for the post Kyle. I hope you’re wrong though, because the thought of 10 more years of the deniers screaming (increasingly loudly) about how global warming is a bunch of not happening BS is a bit more than I for one can take. They could really use this to very damaging political advantage, weakening proactive action just when it’s most needed.

    [Response: When the Keenlyside paper came out, Andy Revkin had a nice blog article on whether the drive for carbon mitigation action could survive a decadal interruption in warming. It's a good question, but one I wouldn't presume to know how to answer. Our best armory for the arguments you fear quite rightly is to build up our understanding of decadal variability and the extent to which it can cloud the long term trend. It's too soon to say whether the current "pause" in warming is anything more than statistics being clouded by one unusual El Nino event, but we should be thinking now about possible explanations just in case something more interesting is going on. --raypierre]

    Comment by Jim Bouldin — 12 Jul 2009 @ 10:18 PM

  23. Greg Simpson wrote in 10:

    Is a linear trend line justified in the first graph? All the forcings seem to be accelerating.

    Not exactly sure why you think that the forcings are accelerating. Methane seems to be picking up a bit, but then again, given the Asian Brown Cloud, so should the negative effects of reflective aerosols. Rate of percentage annual growth for carbon dioxide has certainly increased since the beginning of the 21st century, but this should result in a significant change in the rate of warming any more quickly than the differences between emission scenarios would, and there (according to the models) the differences aren’t significant for the first thirty-some years but progressively become more pronounced from then on — given the cummulative effects of accumulated carbon dioxide.

    However, at least with NASA GISS, it would appear that there is no statistical basis as of yet to claim that the trend in warming has reversed itself, slowed or accelerated from what it was beginning in 1975.

    Please see:

    You Bet!
    January 31, 2008
    http://tamino.wordpress.com/2008/01/31/you-bet/

    However, I am sure that Tamino will appreciate the wavelet analysis and will be looking forward to hearing what he has to say.

    Comment by Timothy Chase — 12 Jul 2009 @ 10:18 PM

  24. #9, Thanks Dhogaza, I look forward to hear either from Raypierre or Dr Swanson.

    I must add on, there are no reasons for the atmosphere as a whole not to warm, no active massive Volcano eruption neither extra sun reflecting aerosols, there is according to some a 1 W/m2 lull in solar forcing at this current solar minima. During an El-Nino episode, at least during this current one, there is cooling possible despite the heat exchanged from the ocean,

    http://data.giss.nasa.gov/cgi-bin/gistemp/do_nmap.py?year_last=2009&month_last=05&sat=4&sst=0&type=anoms&mean_gen=08&year1=1997&year2=1997&base1=1951&base2=1980&radius=1200&pol=reg

    To state that a model or two foresees a lull in warming goes against my own powerful observations of expanding sun disks especially in the Arctic. I have not detected a consistent cooling in the Northern Hemisphere, nor does the temperature record show this, 2007 being the warmest year in history for the Northern Hemisphere (matching record year for Arctic Ocean ice shrinkage), 2008 and also 2009 despite having much cloudier Arctic summers show equally significant ice extent reductions. ENSO merely reflects a state of flux for the entire planetary climate system, of which La-Nina cools and El-Nino warms, but overall the temperature of the atmosphere is warming. As the coming months will show a significant warming for the temperature records.

    1997 compared to 2009 seems adequate

    http://data.giss.nasa.gov/gistemp/tabledata/NH.Ts.txt
    January till May was warmer in 2009 despite La-Nina over past winter

    http://www.cpc.noaa.gov/products/analysis_monitoring/ensostuff/ensoyears.shtml

    as was in 1997 La-nina turned to El-Nino during summer.

    So the evidence, if any about a temperature lull is not observed….

    Comment by wayne davidson — 12 Jul 2009 @ 10:19 PM

  25. Re #21

    You are right, it’s 80 years. Guess I need new glasses!

    Comment by Brian Brademeyer — 12 Jul 2009 @ 10:52 PM

  26. It appears to me that if the HadCRUT3 data since 1980 were modeled with a least-squares analysis, assuming an exponential function, that it would likely model the data better than the green line for the period. If the data was somehow adjusted for changes in solar irradiance over the period, it might show an even stronger increase trend.

    Comment by Geno Canto del Halcon — 12 Jul 2009 @ 10:55 PM

  27. Based on past performance I would not expect this comment to get through moderation.

    Hope springs eternal nonetheless.

    The root cause of sea surface warming is a change in the intensity of solar radiation that reaches the surface of the ocean. There is no doubt that it is upper troposphere cloud that responds to change in local temperature in turn related to periodic change in ozone concentration that is in turn associated with vortex activity at the poles.

    Verification is easy. Simply compare monthly anomalies in 20hPa temperature 10°N to 10°S with monthly anomalies in sea surface temperature at 20-30°S and 260-275°E (off the coast of Chile).

    There has been a strong trend of declining 20hPa and SST since 1978 as the solar wind strength has fallen enabling a stronger flux of mesospheric nitrogen oxide into the stratosphere. Result is steady cooling. The trend to warming SST prior to 1980 is clearly related to a gradually warming stratosphere prior to that date.

    Comment by Erl Happ — 12 Jul 2009 @ 11:02 PM

  28. Dr Swanson,

    I find this approach interesting. Clearly there are teleconnections between the different climate modes, and it would certainly appear (as previous work along these lines would suggest) that the network of climate oscillations can undergo reorganization after they have entered a brief period of synchronization which marks the transition from one regime to the next.

    However, as I understand it what is currently the mainstream view is that what explains the transition from early 20th century warming to the flat period between is the resumption of industrial production and thus of reflective aerosols (predominantly sulfates), and that likewise, it was the passage in the early seventies of laws requiring cleaner emissions that reduced reflective aerosols. Do you see the periods of synchronicity that mark the transitions between regimes as an alternative to this narrative — or as something that might complement it?

    Additionally, if I am not mistaken, a “new” view that has become more or less mainstream is that chaotic systems are especially sensitive to forcing, such that anthropogenic forcing would “project itself… onto the modes of natural variability.”

    Please see:

    But, on the basis of studies of nonlinear chaotic models with preferred states or ‘regimes’, it has been argued, that the spatial patterns of the response to anthropogenic forcing may in fact project principally onto modes of natural climate variability.

    Signature of recent climate change in frequencies of natural atmospheric circulation regimes
    S. Corti, F. Molteni, and T. N. Palmer
    Nature 398, 799-802 (29 April 1999)
    http://www.nature.com/nature/journal/v398/n6730/abs/398799a0.html

    Now if this were the case, changes in the forcing due to reflective aerosols at roughly the beginning of World War II and shortly after the enforcement of the Clean Air Laws in the developed economies might very well explain a transition from one climate mode regime to another — that is, if the climate system is particularly sensitive to changes in forcings. Would you see the approach you are presenting as in essence arguing that climate mode regimes are in fact more autonomous and that at least in the short-run, the climate system is more independent of forcings?

    Comment by Timothy Chase — 12 Jul 2009 @ 11:15 PM

  29. This is a very interesting post. I think what I’m hearing can be usefully be analogized to a familiar situation. We have an automobile with a defective cooling system, we’re descending a hill and seeing the temperature indicator stabilizing, but we can expect it to resume rising once we’ve back on the flats, or going up hill again. Is this a useful and halfway accurate way of thinking about it?

    Jim Bouldin 12 Jul 2009 at 10:18 pm

    [message of fear and loathing]

    Jim, most of the things being proposed in the way of modernizing energy exploitation, capture and management are items that ought be high on a prioritized bullet list for improving the human and planetary condition regardless of what the climate situation is. Stabilizing hydrocarbon prices, preserving what liquid and gaseous hydrocarbon compounds we have available for better uses than combustion, encouraging conservation so as to save money, polluting less, the list goes on. Those are all tasks we need to complete so as to “build a better tomorrow” for reasons unrelated to our climate mess.

    Some of the more “out there” ideas such as geoengineering become more difficult in an adverse policy climate, but those mostly have the common feature of being half-baked in any case and ought to be approached with extreme caution.

    Regardless of what the factually challenged may believe, we should be doing most of what will be required for AGW reduction irrespective of the climate situation. Even if the impossible were to happen and we suddenly discovered that CO2 released in vast quantities were completely benign, we should be moving on from caveman energy habits. It’s incumbent on us to improve how we get energy and what we do with it, the sooner the better, or we’re going to have a more dismal future. That’s really not debatable for anybody with a reasonably broad perspective.

    Frankly, it might be better to push improved energy technologies with climate mitigation being a second tier consideration in whatever pitch is required to capture imaginations and market share. Everybody likes predictable prices, everybody likes getting the same thing for less money; there’s nothing controversial about making things more predictable, less expensive.

    Comment by Doug Bostrom — 12 Jul 2009 @ 11:56 PM

  30. Dr. Swanson writes:

    The HadCRUT3 global mean temperature to the right shows the post-1980 warming, along with the “plateau” in global mean temperature post-1998. Also shown is a linear trend using temperatures over the period 1979-1997 (no cherry picking here; pick any trend that doesn’t include the period 1998-2008). We hypothesize that the established pre-1998 trend is the true forced warming signal, and that the climate system effectively overshot this signal in response to the 1997/98 El Niño.

    I am puzzled by this assumption that the “established pre-1998 trend is the true forced warming signal.” We have a trend that’s been fitted to the period 1979-1997 and shown to also fit the data reasonably well all the way back to 1850. That’s fine, and it seems that Dr. Shunichi Akasofu has made exactly the same point, except that the latter has attributed the same trend to recovery from the Little Ice Age rather than GHG forcing. And given that there wasn’t enough CO2 in the mid-nineteenth century to be causing the same warming as there was in 1975 it seems rather strange to me to be attributing a single linear trend all the way from 1850 until 1997 to GHGs without any mention of the warming trend that already existed in 1850. Has this analysis been simplified?

    Comment by Alex Harvey — 13 Jul 2009 @ 1:03 AM

  31. “there are no guarantees to how the climate may respond. ”
    “if the climate is not behaving as a linear forced”
    “LINEAR” being the critical word. Several people mentioned wild departures from linear.
    Reference: “With Speed And Violence” by Fred Pearce, 2007.
    “The vanishing Face of Gaia” by James Lovelock, 2009, page 153 says that paleohistory shows a sudden 9 degree rise at 450 ppm equivalent. The physics is not stated. We are almost there.

    If we had millions or billions of years of data equal to the data since the late 20th Century, of course you would already have figured out the non-linear equations that are really there. As it is, you can only try to fit linear equations to what you have. I’m glad somebody is using wavelets. The most powerful mathematics is clearly justified. What is really there that you have approximated as linear?

    People like to make “easy” predictions, like sea level rise. Nobody wants to predict something hard, like when will agriculture fail in region X, or will I be able to afford dinner 2 years from now?

    “humanity is poking a complex, nonlinear system with GHG forcing” and this is a dangerous thing to do.

    Thank you for applying the most powerful math you can to try to figure out what the real equations are. We need to know yesterday.

    Comment by Edward Greisch — 13 Jul 2009 @ 1:24 AM

  32. “Also shown is a linear trend using temperatures over the period 1979-1997 (no cherry picking here…”"

    Unless you’re cherry picking a linear trend ?!

    Comment by Rob J — 13 Jul 2009 @ 3:07 AM

  33. That was one of the best articles I’ve read here. Thank you. It will be interesting to see this tested in the coming years, unless some other unknown factor confuses us.

    Comment by Samuel Watterson — 13 Jul 2009 @ 3:47 AM

  34. It would be good if Dr Swanson acted as tag team partner for Al Gore when GW denier Senator Steve Fielding presents Gore with ‘irrefutable’ evidence of cooling. Gore could step out of the ring for the heavy action.

    Sure last Australian summer was cold at times and my pumpkins split with frost. There were also unprecedented bushfires and record high temperatures. Maybe the debate should not be politician vs politician.

    Comment by Johnno — 13 Jul 2009 @ 3:59 AM

  35. In the Swanson and Tsonis paper it is suggested that the decadal variations of the global mean temperature, the climate shifts, observed in the 20th century are basically caused by the synchronization of four modes. I guess that the synchronization events occur by chance.

    How is it then possible that the IPCC climate models can replicate these decadal variations at exactly the same years? For the wrong reasons?

    Comment by viento — 13 Jul 2009 @ 5:15 AM

  36. “Raypierre, its completely counter intuitive to suggest that there will be a pause in Global Temperature warming.”

    There isn’t.

    Read the fine article, Wayne.

    if 1998 was an exceptional change, that change can make any nearby values exhibit a change that isn’t real, just the consequence of no longer having that exceptional change.

    Look at the graph without the 1998 value. Nothing weird going on there.

    It isn’t saying there’s a pause. In fact the article even says that it isn’t talking about a pause. It’s talking about a datapoint that is exceptional and how it can affect your perveption of what’s going on.

    Note, for example, the slope of the green line. Without 1998, the mean fit slope doesn’t change much. But if you take only a small slice near that exceptional datapoint, you get huge variations.

    If not, where were you in 1999 when the graph was pounding right through the roof? You weren’t yelling “THIS IS PROOF! AGW IS REAL!!!”. You kept strangely quiet.

    Comment by Mark — 13 Jul 2009 @ 5:49 AM

  37. “How do I answer the sceptics/deniers who utilise the cooling since 1998, matched with the trend lines in the IPCC reports that show warming climbing while the reality is cooling or at least flat lining?”

    What you do is add up the last 10 years global mean. This period includes the “cooling” years and excludes the “hottest year” 1998.

    You then compare that to the 10 years previous to that. This includes the warmest year and the warming that they describe as having reversed (in the last 10 years).

    Compare the two.

    The last 10 years, despite being “cooling” is about 0.2C warmer.

    Comment by Mark — 13 Jul 2009 @ 5:53 AM

  38. “If El Nino is put up as the reason why doesn’t the the forecast’s take that into account and show it???”

    Because it’s a chaotic event. Like large volcanic eruptions or solare flares.

    You can forecast what the average effect of such would be, but if it is big enough to show up on the global picture, you will see a deviation while it is in effect away from its average effect and later a deviation the other way.

    Comment by Mark — 13 Jul 2009 @ 5:55 AM

  39. “If the ‘97-’98 change is “better than 3 standard deviations of interannual variability” as you state, might that not simply indicate that the interannual variability is not normally distributed?”

    Only if it happens significantly more than once every 100 ish years.

    Comment by Mark — 13 Jul 2009 @ 5:57 AM

  40. The coupling-decoupling mechanism and the means by which it is quantified seems sound. That all times of enhanced coupling would tend to cause a pause in the warming trend does not seem likely. Depending on the specific phases enhanced greater coupling should be able to enhance warming as we have seen with the phasing of PDO and el nino. The slow radiative dissipation argument does not seem plausible to me on the slow time scale indicated for such a short term event.

    Comment by mauri pelto — 13 Jul 2009 @ 7:34 AM

  41. Good I was in charge of the high school physics ripple tanks. I think that helps me understand this. You get bigger amplifications and troughs when the 2 ripples intersect…(I’m a bit fuzzy, but that’s what I recall from 45 yrs ago). By analogy, one ripple could be the natural variability, and the other, the forcing from GHGs. Then you add in other ripples from other aspects, and you could get whopper amplifications and troughs…..

    Another thing I’ve been wondering for the past 20 yrs is that “episodes” such as el ninos might be getting stronger and/or more frequent due to global warming. (Or is the author also saying that?) In other words, not only does the micro/meso impact the macro climate level, but macro impacts the micro/meso climate/weather levels.

    I vaguely remember that when I first learned about el nino over 40 yrs ago, they said they come about every 7 years. Timothy Chase (#18) says, “every two to five years.” Maybe my memory is wrong, or perhaps the science back then wouldn’t have been as advanced….

    Also, I don’t know about that idea of record-breaking temps again resuming by 2020. Right now in the Rio Grande Valley we’ve been in record-breaking, above 100 F weather for several weeks, and the “cunecula” (heat wave that goes from July 14 thru the end of August) hasn’t even started yet. Houston got 114 a couple of weeks ago. I know, I know, single weather events don’t equal climate, but thought I’d balance out the claims of denialists in who say it’s cooler than usual in their area.

    Comment by Lynn Vincentnathan — 13 Jul 2009 @ 8:11 AM

  42. Dear Dr Swanson,

    I am puzzled. You identify three episodes (during the 1910’s, 1940’s, and 1970’s), with the 2000′s as presumably the fourth, yet you draw a trend line through 1950 to 2000. Shouldn’t each episode have a separate trend line?

    Either we have a dynamical system as you claim in your paper, or the system is linear as you infer with your straight trend line. Which is it?

    Cheers, Alastair.

    Comment by Alastair McDonald — 13 Jul 2009 @ 8:36 AM

  43. Mark:

    Read the fine article, Wayne.

    It isn’t saying there’s a pause. In fact the article even says that it isn’t talking about a pause.

    From the fine article:

    Regardless, it’s important to note that we are not talking about global cooling, just a pause in warming.

    Comment by dhogaza — 13 Jul 2009 @ 8:50 AM

  44. “Shouldn’t each episode have a separate trend line?”

    No, because the 1910′s, etc are all proofs that saying “this decade is showing a low trend” means nothing. This has happened many times in the past, yet rather than getting back to what was had before this “cooling!” we have temperatures higher than before.

    So saying “this last 10 years has a trend much lower” means nothing since the same has happened before and yet we are still much higher at this lower ebb than any time before 1979 (IIRC). Even those years showing a peak.

    Comment by Mark — 13 Jul 2009 @ 8:54 AM

  45. “You get bigger amplifications and troughs when the 2 ripples intersect…(I’m a bit fuzzy, but that’s what I recall from 45 yrs ago). By analogy, one ripple could be the natural variability, and the other, the forcing from GHGs. Then you add in other ripples from other aspects, and you could get whopper amplifications and troughs…..”

    Constructive interference was done in Physics when I was 14.

    Is it no longer done???

    Comment by Mark — 13 Jul 2009 @ 8:57 AM

  46. Re #30

    Dr. Shunichi Akasofu has made exactly the same point, except that the latter has attributed the same trend to recovery from the Little Ice Age rather than GHG forcing.

    And what caused that ‘recovery’?

    [Response: Yes, this points up a common misconception about the operation of climate. Though we speak of "thermal inertia," it's not really inertia in the sense of Newtonian mechanics. If you start a warming trend by increasing a climate warming forcing and then zeroing it out, it does not (unlike a body in notion) tend to keep on warming unless you do something later to stop it. Warming is a damped response to the current forcing, and the minute you zero out the forcing, the trend will turn the other way. "Committed warming" is only committed because the scenario there is not zeroing out the GHG forcing, but rather freezing its value, giving the climate time to catch up. In this sense, the dynamics of climate change is more Aristotelian than Newtonian. --raypierre]

    Comment by Phil. Felton — 13 Jul 2009 @ 8:59 AM

  47. “That all times of enhanced coupling would tend to cause a pause in the warming trend does not seem likely.”

    An exceptionally strong El Nino brings no *new* energy into the system. What it does is change the location of it and makes it easier to spot (to an extent). But that doesn’t make any more energy in the system if nothing else happened to force a change.

    Therefore it’s likely that any discourse to the other side in the subsequent period will have changed.

    E.g. El Nino keeps warm water at the surface longer. Therefore what would have gone down into deeper ocean is kept nearer the surface. Then the next La Nina has not had the benefit of that introduction of that energy it would normally have. And it hasn’t had enough time to even this out by drawing energy from other places (which it could do for later La Nina). Therefore a greater cooling because the deep water didn’t get the warmth a more normal El Nino would have let it take.

    PS I can never remember which way round it goes El Nino warming? I’ve seen it plenty times, but it just doesn’t seem to stick.

    Comment by Mark — 13 Jul 2009 @ 9:16 AM

  48. #18
    Timothy Chase :
    12 Jul 2009 at 10:01 pm:

    … but things can change in a month’s time, and while the current El Nino is expected to last through Fall and Winter (and in fact roughly a year if it is typical), the previous one (early 2007, I believe) burned itself out unexpectedly and we fell back into a La Nina.

    I think you mean early 2008. In early 2007 the various ENSO metrics were all dropping as what turned out to be the 2007-2008 La Nina emerged. It’s true that things change unexpectedly over a month’s time, but July is during the time of year when rapid changes in the ENSO state are less common, while the one that ‘burned out’, which I think you refer to, ‘burned out’ earlier in the year when such reversals are more common.
    See pg 26 (or 22) of this ENSO status and evolution report. The most recent ONI value (April – June) of 0.2 is greater than the peak ONI value of 0.0 reached in early 2008, when the 2007-2008 La Nina ended. (Note that whether the Pacific went back into La Nina is debatable; the NOAA official metric requires at least 5 consecutive overlapping 3 months periods with ONI less than or equal to -0.5 . Following early 2008, there were only 4 overlapping 3 month periods of ONI equal to or below -0.5, as you can see on pg 26.) (See here for a different (MEI) metric which tells a similar story.)

    Comment by llewelly — 13 Jul 2009 @ 9:22 AM

  49. 43, OK, I used the wrong word.

    “Raypierre, its completely counter intuitive to suggest that there will be a pause in Global Temperature warming. ”

    It isn’t a pause in global warming trend (GT Warming) which you need more than 10 years (around 30 will do fine) but a drift from the trend (which CAN be seen in 10 years, if barely) that added to the trend which hasn’t paused and gives an *appearance* of the climate (30 year) trend of having stopped.

    It would take another 2 10-year periods to prove the climate trend having stopped.

    At least that’s the difference I got from Wayne’s post about the article and the article itself.

    Comment by Mark — 13 Jul 2009 @ 9:26 AM

  50. Much ado, yes, but what about? The idea that the inter-annual change between 1997 and 1998 is anomalous needs more support. First, is it really three standard deviations? What if the year definition is phase shifted by six months? If it is 3 standard deviations, why would that be an anomaly? With enough data, the absence of any points at three standard deviations would be the curiosity, indicating a non-normal distribution, rather than their presence.

    It seems to me that the rise is marked by a real physical event, El Nino, rather than its statistical rank in a larger record, and the stronger statement is that even the largest “variability” events can’t hold a candle to the long term trend of temperature increase. They are down in (or are) the noise.

    In any case, it seems to me that it is quite difficult to identify a “break” in the mean temperature trend from the date shown here and even more so from the GISS data, mentioned but not shown. So, it is hard to base a paper on that.

    Comment by Chris Dudley — 13 Jul 2009 @ 9:50 AM

  51. Related to linear and non linear systems
    http://en.wikipedia.org/wiki/memristor

    Comment by save gaia — 13 Jul 2009 @ 9:51 AM

  52. “It seems to me that the rise is marked by a real physical event, El Nino, rather than its statistical rank in a larger record,”

    I think the idea is that an extreme event if included in a graph skews the graph analysis for much longer.

    Therefore without 1998 you can (barely) get away with 10 year trends.

    With it, you have stuffed up your ability to say anything about the underlying trend for ~10 years either side.

    A bit like a ringer in a company football game. That one player will dominate and the team will win. But the team isn’t really all that much better. That one player makes the efforts of the others virtually worthless BECAUSE they are so good.

    Comment by Mark — 13 Jul 2009 @ 10:35 AM

  53. “The contentious part of our paper is that the climate system appears to have had another “episode” around the turn of the 21st century, coinciding with the much discussed “halt” in global warming. Whether or not such a halt has really occurred is of course controversial (it appears quite marked in the HadCRUT3 data, less so in GISTEMP); only time will tell if it’s real. Regardless, it’s important to note that we are not talking about global cooling, just a pause in warming. ”

    You make many important points but I want to point out a contradiction in the para above that leaps off the page at this skeptic (yes – I am a skeptic).

    You state “only time will tell if global warming has stopped”

    then you state, unqualified, that “we are not talking about global cooling, just a pause in warming”

    It is critical that everybody understand (as this paper asserts) that global warming does not equate to monotonic increase in temperature. Global climatic variable will always be a fact of life and in this lite recent lack of warming does not prove or disprove anything. A climate that oscillates over a positive anomaly slope is most definitely still warming. But only time will tell.

    However, it does indicate to this skeptic that climate is subject to many forces not all of which are fully understood. While we humans certainly do need to clean up our act we also need to approach this issue, especially the policy aspects, with clear heads and eyes wide open.

    thank you

    [Response: And decadal fluctuations in ocean-atmosphere heat exchange are one of those things we don't fully understand. But, we do understand the physics of energy balance well enough to say that they cannot possibly delay warming indefinitely. The energy balance piper must eventually be paid. --raypierre]

    Comment by Eric Hansen — 13 Jul 2009 @ 10:37 AM

  54. Great post, thank you Kyle.

    Comment by Jim Galasyn — 13 Jul 2009 @ 10:47 AM

  55. Are there exact years for these climate shifts? 1910, 1940, 1970, 2000 is every 30 years.

    Comment by MIke — 13 Jul 2009 @ 11:02 AM

  56. “then you state, unqualified, that “we are not talking about global cooling, just a pause in warming””

    Yup, because it will take another 10-20 years to find out if it’s actually cooling.

    There have been many pauses in the upward trend of global temperatures.

    Comment by Mark — 13 Jul 2009 @ 11:23 AM

  57. “However, it does indicate to this skeptic that climate is subject to many forces not all of which are fully understood.”

    Uh, subject to many forces: check.

    Not all of which are fully understood: check.

    Implication that conclusions cannot be drawn: false.

    Comment by Mark — 13 Jul 2009 @ 11:24 AM

  58. You make many important points but I want to point out a contradiction in the para above that leaps off the page at this skeptic (yes – I am a skeptic).

    That’s because you’re wearing your skeptic-colored glasses.

    There’s no contradiction at all. His point is that if warming has “halted” (note his use of quotes), it is only temporary – a pause. The authors of this paper in no way suggest that AGW isn’t happening.

    It is critical that everybody understand (as this paper asserts) that global warming does not equate to monotonic increase in temperature.

    Well, duh. Climate science has never suggested it would be monotonic, this isn’t what’s new about this paper. Skeptics are the only people who insist that there should be a monotonic increase in temperature, and then use the fact that (duh) there isn’t to scream “AGW is false!”

    So go tell those folks over at WUWT that one shouldn’t expect monotonic increases, please!

    However, it does indicate to this skeptic that climate is subject to many forces not all of which are fully understood.

    This paper doesn’t discuss any “new force which isn’t fully understood”.

    Comment by dhogaza — 13 Jul 2009 @ 11:27 AM

  59. I give Swanson credit for recognizing the 1997/8 step change. However, there are better ways to show it, and a similar step change took place during the 86/7 El Nino as well. The background trend that Swanson argues is the true trend (independent of the 1997/8 step change) is actually caused by step-changes related to the 76-8 and 86/7 El Nino events.
    I’ve written a short response to his post, here:
    http://climatechange1.wordpress.com/2009/07/13/swansons-not-so-novel-post-at-realclimate/

    Comment by Carl Wolk — 13 Jul 2009 @ 11:56 AM

  60. #58, dhogaza, there is nothing out there suggesting this pause. It is good to remind that Hadley
    Arctic ice sheet model failed by 40 years! I would reconsider if present El-Nino peaks same as 1997-1998 and world averages would show a cooling. So far no such thing. Temperature variability has a lot to do with planetary wave positions and the weather they give. Planetary waves seem adjusted for a strong El-Nino episode at present.

    #41 Lynn, Up here in most parts of Canada its incredibly cloudy, you should see many Canadians on holidays chasing your heat wave :(. Variability and cloud extent are joined at the hip, temperature projections fail when clouds play havoc as they do now. This is why world wide averages are key. You seem to be in a heat spot, if El-Nino grows even more, as BTO song goes:
    “you ain’t seen nothing yet” , come up here in the cloud shade for a cooling!

    Comment by wayne davidson — 13 Jul 2009 @ 12:05 PM

  61. Carl Volk; I stopped reading when you described RC as being an “alarmist site”. Tells one all one needs to know, really.

    Comment by dhogaza — 13 Jul 2009 @ 12:16 PM

  62. dhogaza, there is nothing out there suggesting this pause

    I tend to agree, but … I was commenting on Eric Hansen’s misinterpretation of Kyle Swenson’s words, nothing more than that.

    Comment by dhogaza — 13 Jul 2009 @ 12:30 PM

  63. As best I can tell from reading the article, the authors have nothing to contribute to our understanding of climate change. What they seem to be suggesting is that the fit of the models to the data can be improved if the models include feedback among the recognized macro climate states (the ENSO, the Pacific Decadal Oscillation, the North Atlantic Oscillation, and the North Pacific Index). But all the independent drivers of climate are still the same.

    I have a problem with this on a conceptual (model construction) level. The real dependent variable we are interested in is the change in the heat content of the biosphere on Earth. Atmospheric temperature is only one component and a minor one at that. (The others are the oceans, cyrosphere and the top inch or 4 of the surface of the Earth.)

    By only presenting a statistical analysis of a minor part of the total system, the results are vulnerable to false signals in the dataset.

    Physical models of a single aspect of the climate system have a physics based explanation and help us understand the system by looking at a single component in isolation. Such a model is not complete, but is is well grounded in physical principals and demonstrates the first order effects of a single component.

    But the author’s math is not grounded in a single physical principal. It is an analysis of a single dependent variable at an intermediate level of the total system and is not isolated from influences from the other components. The entire set of results could just be artifacts of other, un-named, processes.

    I fail to see what predictive value there is in this approach.

    Comment by Greg — 13 Jul 2009 @ 12:50 PM

  64. I would have 2 critiques of this post, both to do with the first figure and interpretations thereof:

    1st: The implication that our best guess as to the underlying signal is a linear trend of about 0.1 degree per decade. We have some knowledge about underlying forcing trends, and about the theoretical response to such trends. Indeed, the IPCC AR4 report has predictions out to 2030, with closer to 0.2 degrees per decade rise on average.

    2nd: The inclusion of the Smith et al. (2007) projection as linear. The Smith paper has a graph showing a detailed projection,with uncertainty bounds, and it would be appropriate to include the more detailed projection.

    In general, while papers such as this – or, for that matter, Smith (2007) or Keenlyside (2008) – are always interesting and welcome additions to the literature, I feel that they are too quickly leapt upon as better mousetraps because they explain the last couple of years better than the standard model. And yet, the 3 approaches yield 3 different answers. I would prefer many more caveats about the _preliminary_ nature of such a new study until and unless it is either supported by replication by a number of other groups or it makes a bold, new, unlikely prediction which then comes true.

    See the earlier post about “Science at the bleeding edge”.

    Comment by Marcus — 13 Jul 2009 @ 12:55 PM

  65. “Arctic ice sheet model failed by 40 years! ”

    Failed in what way?

    Underestimated the speed of reduction, most likely.

    This hardly makes a good example of how we’re A-OK because models get things wrong…

    Comment by Mark — 13 Jul 2009 @ 1:20 PM

  66. Mark quotes Wayne Davidson (60):

    Arctic ice sheet model failed by 40 years!

    … then responds in 65:

    Failed in what way?

    Underestimated the speed of reduction, most likely.

    This hardly makes a good example of how we’re A-OK because models get things wrong…

    “A-OK”? Mark, Wayne has undoubtedly been accused of a number of things in the past, but complacency is definitely a new one on me…

    Comment by Timothy Chase — 13 Jul 2009 @ 1:56 PM

  67. This hardly makes a good example of how we’re A-OK because models get things wrong…

    If you’d pay attention you’d understand that Wayne’s not saying any such think, he’s saying that things are WORSE, not A-OK. That yes, failed by *underestimation*, just as you say.

    If you read more carefully maybe you’d quit subjecting so many people to unappreciated friendly fire.

    Comment by dhogaza — 13 Jul 2009 @ 1:56 PM

  68. “That yes, failed by *underestimation*, just as you say.”

    Would’ve been nice if he’d said.

    “If you read more carefully maybe you’d quit subjecting so many people to unappreciated friendly fire.”

    Sorry Wayne, but dhog, where’s the bleeding fun in that?

    Comment by Mark — 13 Jul 2009 @ 2:20 PM

  69. Rob J (#32) says: “Unless you’re cherry picking a linear trend ?!”

    I don’t think you can call fitting a linear trend line to data a “cherry pick”. It is just the simplest thing that you can do…i.e., it is the first (non-constant) term in a higher order expansion. And, alas, with global temperature data over the sort of times that we have and because of the noisiness of this data, it is really as high in the expansion as one can justify going.

    Attempts by people like Roy Spencer to fit a 5th-order(?) polynomial to the data are completely ludicrous and even Spencer himself put on the caveat that he did not mean that polynomial to have any predictive power for the future; But, it would have been better if he hadn’t shown it at all!

    Comment by Joel Shore — 13 Jul 2009 @ 2:25 PM

  70. If we replace the phrase “the climate system” with a more specific name, we can at least agree on what we are talking about. For the purposes of decade-scale variability, the main components of interest would be:

    1) Atmosphere

    2) Oceans

    3) Glaciers and sea ice

    3) Biosphere and soil

    4) Volcanic events

    Volcanic events are a good place to start, because they are almost truly random events which are insensitive to the state of the ‘the climate system’. There are no plausible “modes of variability”.

    Now, consider the atmosphere. Are there modes of variability in the atmosphere, “synoptic temporal periodic structures”? Despite many such claims over the years, the answer is generally not – the stratospheric equatorial jets being one exception. For a good discussion of that, see Ed Lorenz’s book, “Essence of Chaos”:

    In the following pages I shall introduce the atmosphere as an example of an intricate dynamical system, and present the case for believing that its irregularities are manifestations of chaos. After a brief overview I shall enumerate various procedures through which the presence of chaos might be confirmed. Finally, I shall examine some of the consequences of the atmosphere’s chaotic behavior.

    The oceans seem to behave in a similar manner, just slower – and the oceans are the most likely place to find any decade-scale periodic modes.

    First of all, the synoptic oceanic structures are poorly defined and studied due to lack of good data coverage. This is unlike the atmosphere, where decades of radiosonde and satellite data have given synoptic meteorologists a lot of experience with synoptic atmospheric structures. (The dynamical approach involves understanding why synoptic structures form in the first place, rather than just a statistical analysis of observed structures – before computers, all weather forecasters were strictly synoptic in method).

    The dynamic models of the oceans are hard to test because of such lack of data, which has led some people to treat the output of dynamic models as a source of synoptic data, much as if a model of atmospheric circulation was used as a reliable indicator of how cold fronts, etc. behaved, in the absence of radiosonde and satellite data.

    Then, the frequency with which such modeled synoptic structure change over time is given as evidence of a natural periodic cycle, or is correlated to some distant piece of data – sea surface temperatures, for example, or fishing records, which is supposed to be a reliable indicator of the underlying periodic synoptic structure. This procedure is not really that reliable when applied to fluid dynamic systems – works great for orbital phenomenon, however, where underlying periodicity is expected. For example, if you wanted to calculate the orbit of Saturn’s moons from a small amount of observational data, you could probably get away with this approach – but it doesn’t work for ENSO.

    With El Nino and La Nina, you have high sensitivity to initial conditions, which means that ‘mode projection’ is not useful for predicting the future. This is why people haven’t been able to reliably predict ENSO events more than 6-9 months in advance – just as major atmospheric weather events cannot be predicted more than 1-2 weeks in advance, tops. That’s related to the different mixing times of the atmosphere and ocean, and is a manifestation of the chaotic behavior – which doesn’t mean random behavior.

    For the longer-period modes, evidence is even slimmer – and what does an AMO or PDO ‘event’ look like, anyway? What is the physical basis of ‘mode coupling’, as well? On such time scales, other plausible periodic modes involve soil, vegetation and ice sheets. With the ice sheets, there is evidence that the millenial variation is timed by orbital variations, as long as conditions are such that ice sheets can be present – but for the rest? How about claimed periodic modes of desert expansion and ‘megadrought’, for example?

    Desertification is a complicated picture, as it involves soil moisture, atmospheric circulation, regional variations in geology and soils, and biosphere responses. There are regions that have suffered from extended droughts, but the evidence for a periodic driver (rather than just random drift) is also slim. Notice also, that during these past megadroughts global sea levels remained constant. Thus, regional factors probably played the major role in such climate shifts, not global atmospheric forcing (which is what is driving today’s climate change).

    All in all, it seems that the correct way to view unforced natural variability in the atmosphere and oceans is as a manifestation of chaotic phenomenon on an attractor, not as the result of a combination of periodic modes of behavior. Practically, this means that better ocean data coverage is needed, plus decadal modeling approaches similar to those used for weekly weather forecasts, i.e. initialization of the ocean state.

    Regardless of what you think about that, no one can honestly use either point of view to claim that fossil fuel-sourced CO2 isn’t warming the planet at an unprecedented rate, well beyond anything seen in the past four million years or so (current CO2 increase rates being 20-30 times greater than anything seen in the paleoclimate record.) This hasn’t kept people from trying to claim that a) the system is chaotic, so nothing can be predicted, or b) the system is periodic, so the warming is just due to overlapping cycles.

    Hopefully, that illustrates the difference between a legitimate scientific debate over how natural systems like this behave, and the abuse of a legitimate scientific debate to push various kinds of opinions, propaganda, etc.

    It is fairly important that both scientists and the general public understand how the PR industry attempts to manipulate science to serve other interests – it is not really a new phenomenon, just look at the history of eugenics, creationism and Lysenkoism for more examples.

    Comment by Ike Solem — 13 Jul 2009 @ 2:30 PM

  71. #58 dhogaza says “Well, duh. Climate science has never suggested it would be monotonic, this isn’t what’s new about this paper. Skeptics are the only people who insist that there should be a monotonic increase in temperature, and then use the fact that (duh) there isn’t to scream “AGW is false!”“.

    Well, to this simple observer of the AGW scene, all of the AGW predictions, viewed as monotonically climbing graphs, show exactly the opposite of what dhogaza claims. And skeptic friends tell me that the inability of the models to predict anything other than monotonically climbing temperatures is why there’s been a rebranding of AGW as “climate change”. It seems a pity that the models seem unable to take into account significant ocean cycles, solar cycles, etc. To the simple observer it seems either that the models are inadequate or that there’s been a failure to communicate the realities of AGW (leading to articles like the above which will only ever be read by the already convinced.)

    There’s a real dilemma here that AGW proponents need to confront if they’re to win the hearts and minds of the vast mass of people who can’t appreciate the sophistries of AGW justifications and qualifications. And in these tough times, a lot of hearts and minds remain to be won.

    [Response: Models do take into account solar cycles. The long term solar variability is in the IPCC "natural forcing" runs, and many IPCC runs also contain the 11 year cycle. K.K. Tung has shown that many of the models have the correct temperature response amplitude at 11 years, so they seem to be able to take into account that. And you are completely wrong that the models can only show a monotonic increase. If you have that impression, it's only because certain people love to draw a misleading comparison between test runs with CO2 increase alone and the real world, which has other forcings in addition. Models can simulate a temperature decrease in response to volcanic eruption, strong increase in aerosol forcing, and many other things. The Keenlyside et al paper shows that the ocean dynamics can temporarily offset cooling; it may well be true that coupled models underestimate decadal variability, but that is where we are still on the learning curve. Where that shakes out has zero chance of being able to significantly affect climate sensitivity, though. It just affects how long you have to wait to see the full warming. --raypierre]

    Comment by Alex — 13 Jul 2009 @ 2:44 PM

  72. #69 Joel Shore:
    “Attempts by people like Roy Spencer to fit a 5th-order(?) polynomial to the data are completely ludicrous and even Spencer himself put on the caveat that he did not mean that polynomial to have any predictive power for the future.”

    Actually it was “only” a 4th-order polynomial. He’s stopped that now, BTW.

    For a short history of polynomial fitting of global temperature record, see:

    http://deepclimate.org/2009/04/09/the-alberta-oil-boys-network-spins-global-warming-into-cooling/

    Comment by Deep Climate — 13 Jul 2009 @ 2:46 PM

  73. Well, to this simple observer of the AGW scene, all of the AGW predictions, viewed as monotonically climbing graphs, show exactly the opposite of what dhogaza claims

    That’s because you’re looking at the average of many runs. Each individual shows wiggly-wiggles, not a monotonic linear change in global temperature. Climate in the real world is expected to respond like the wiggly-wiggle output of a single run. If you had 100 planet earths and could average the wiggly-wiggle response to forcing of each, that AVERAGE would look monotonically increasing. But you wouldn’t see each individual planet responding monotonically.

    If you read a little bit you could learn this yourself.

    And skeptic friends tell me that the inability of the models to predict anything other than monotonically climbing temperatures is why there’s been a rebranding of AGW as “climate change”.

    Wrong on both points. They don’t suffer from the stated inability, and it’s not why the term “climate change” was adopted.

    Again, if you were willing to invest some personal time into researching this you’d realize you were wrong.

    It seems a pity that the models seem unable to take into account significant ocean cycles, solar cycles, etc.

    Well, seeing as you’re wrong about this, too, I think something else is a pity and it has nothing to do with the work of climate modelers …

    There’s a real dilemma here that AGW proponents need to confront if they’re to win the hearts and minds of the vast mass of people who can’t appreciate the sophistries of AGW justifications and qualifications.

    Well, when people lie to you (intentional or not, your friend may also be simply ignorant rather than dishonest), and you accept those lies uncritically, whose fault is it? Scientists.

    Step back and think about the claims you’ve made … do you really think that thousands of climate scientists are SO STUPID that they’d build models that don’t include basic physical features, don’t demonstrate the kind of natural variability seen in the real world, etc, as you claim?

    [edit]

    Comment by dhogaza — 13 Jul 2009 @ 3:11 PM

  74. Alex 13 Jul 2009 at 2:44 pm

    “sophistries”

    “Arguments that seems plausible, but are fallacious or misleading, especially one devised deliberately to be so.”

    You just can’t help yourself, can you?

    Comment by Doug Bostrom — 13 Jul 2009 @ 3:14 PM

  75. Re #6: Yvan Dutil beat me to the punch — I guess I am slow to read posts over the Boreal Summer.

    In a very simple sense, if you allow greenhouse forcing or global warming to be a linear trend over the past century of +0.7°C/100 yrs and you allow for a AMO-style 60-year cycle of ±0.1°C, and add these curves together, you can recreate much of the temperature trends of last century (minus all of the shorter-term wiggles). Follow this until about 1997 when there appears to be a distinct departure from this upward-trend and natural cycle (see http://www.toddalbert.com/files/images/temps.gif for a cartoon sketch). Could this suugest that we’ve passed a tipping point and the climate system is now settling into a new regime? As we approach new warming thresholds (i.e. 2°C) will we see more jumps? We understand that because of all of the feedbacks involved, the system is not linear. So why should we be surprised to see jumps and plateaus in the temperature record.

    Additionally, I still hold that global average temperature is not a great measure of temperature and invite my colleagues to help think up some alternatives.

    Comment by Todd Albert — 13 Jul 2009 @ 3:21 PM

  76. #71 Alex

    Are you saying that science education has left the public with difficulty grasping the idea of some unpredictable natural variability superimposed on more predictable underlying trends? I do see that difficulty with many of my students. The analogy I like to use (and which is probably stated more eloquently elsewhere on this site) is that two or three warm days in the middle of Winter don’t mean that Spring is right around the corner.

    As far as the original post is concerned, the notion that the natural variability of climate provides clues to the sensitivity and response time of climate to unnatural forcings was very familiar to me as a physical chemist, where the “fluctuation-dissipation theorem” is a statement of the very same reasoning to molecular systems.

    [Response: Indeed, there is a great deal of interest currently in using fluctuation-dissipation theorems for nonequilibrium systems like climate. There were several interesting presentations on this at the Princeton Theory Center climate school in which I recently participated. --raypierre]

    Comment by jkga — 13 Jul 2009 @ 3:30 PM

  77. Its swell to read Raypierre again on this site….

    [Response:It's nice to be appreciated. I've been taking a self-enforced sabbatical from RealClimate while trying to finish off writing two books plus a major review on Neoproterozoic climate. I hope to be back on a more regular basis in the Fall. --raypierre]

    #66, Timothy, the model animation in question use to be on this page:

    http://www.metoffice.com/research/hadleycentre/models/modeldata.html

    It showed 2007 similar ice minima in the year 2040 or so. My question remains, why they got it wrong?? Its a shame that they don’t display this animation again for a means of finding out just why they underestimated the melting so radically. If they do such a mistake, then not knowing why triggers doubt, in all their models, albeit ice is more complicated. But as written, 2007 the warmest year in the Northern Hemisphere, coincided with the greatest ice minima in history, this is definitely a different but obvious type of coupling, its hotter ….. there is less ice… Same thing is happening right as I write, 2009 ice extent is equal to 2008. Despite a hugely cloudy Arctic since about mid April. For anyone to claim a pause in warming would mean a stop in disappearing Multi year ice, that is not happening. The pause needs some evidence, if the current El-Nino becomes as strong as 97-98 lets see what Global temperatures say….

    Comment by wayne davidson — 13 Jul 2009 @ 3:55 PM

  78. “It [supposed halt in global warming] appears quite marked in the HadCRUT3 data, less so in GISTEMP.”

    Echoing several others above (e.g. Chis C., Timothy C and so on), I don’t really see the evidence for a “halt” at all in GISTemp, although there is perhaps some in HadCRUT.

    For one thing, according to GISTemp, 2000s on average are 0.19 deg above the 1990s.

    For another, the linear trend in GISTemp from 1979 onward has been rising and peaked as recently as 2007. It is down in 2008, of course, but that year seems to be an outlier affected by the confluence of La Nina and long inter-cycle solar trough. And the trend is still well above those based on any end year between 1997 and 2000 (even 1998).

    See:
    http://deepclimate.files.wordpress.com/2009/05/global-surface-trends.gif

    I’m looking forward to the pending Tamino post on this topic.

    Comment by Deep Climate — 13 Jul 2009 @ 4:02 PM

  79. Deep Climate (#72) says: “For a short history of polynomial fitting of global temperature record, see:
    http://deepclimate.org/2009/04/09/the-alberta-oil-boys-network-spins-global-warming-into-cooling/

    Thanks, DC! Very interesting! I appreciate all the research you do in ferreting out all the goings on in the climate contrarian world!

    Comment by Joel Shore — 13 Jul 2009 @ 4:12 PM

  80. Re: response to 8. This is a question I’ve been meaning to ask Real Climate. Is the rate of heat exchange between the surface and deep waters of the ocean so robust that we can rule out changes in circulation that would cause global warming to cease, reverse or slow down for decades or centuries? Or conversely, could a change in heat exchange suddenly cook us all? I’ve thought the answer to this would be “probably not but we don’t know enough to say for sure”, or “impossible”. But the answer Raypierre gives to Hank Roberts makes it sound like “perhaps”.

    Comment by Andy — 13 Jul 2009 @ 4:18 PM

  81. I am a science enthusiast with limited training, but an expert drawing instructor, which makes it hard for me to ignore the obvious; telling the truth about what you see without fear or preconception is the basis of learning how to draw:

    1. On 1998, how can anyone look at the any graph and not see that it is out of the overall trend? Why does this need to be repeated, how is it not obvious?

    2. On weather, how come we get all the factoids about cool weather but nothing about heat? There’s lots of it going around; in addition to that pointed out above, how about Brazil which seems to be missing winter altogether this year? Some people might be a bit surprised if they took a good look at what is going on currently in the Arctic, let alone Greenland. So we have a lot of melt and some cooler wetter weather in the northern reaches are the area south of this melting. How is that not likely? Ice in a pan of water, anyone, doesn’t it cool the water as it melts, but overall warms more as it diminishes?
    (some background on various melting events, I love the one about the melting witch!):
    http://climatechangepsychology.blogspot.com/

    3. On climate change vs. global warming, those using words to describe events know that climate change is one way to describes some effects of global warming which loosely describes the effects of heat-trapping greenhouse gases. There’s no legerdemain here except those who created the talking point for the sake of argument.

    Ike Solem, thanks. I’ve missed you over at DotEarth.

    dhogaza, thanks for this neat summary of the problem:
    -
    “Well, when people lie to you (intentional or not, your friend may also be simply ignorant rather than dishonest), and you accept those lies uncritically, whose fault is it? Scientists.

    “Step back and think about the claims you’ve made … do you really think that thousands of climate scientists are SO STUPID that they’d build models that don’t include basic physical features, don’t demonstrate the kind of natural variability seen in the real world, etc, as you claim?”

    Comment by Susan — 13 Jul 2009 @ 4:23 PM

  82. Alex (# 71);

    The key issue here is to understand the nature of the “noise” inherent in some climatic time-series record, in this case the global mean temperature anomaly. As demonstrated by a number of recent papers including the discussed Keenlyside paper, as well as Easterling and Wehner 2009 it is entirely possible to have some time interval (which is relatively short compared to the timescale in which radiative forcing from CO2 is important) in which a flatline or even negative trend is present. For instance if you can upwell cold water from the deep oceans and bring it to the surface then this will temporarily do the trick. This, among other reasons, is why you see a lot of wiggles in the blue line in Fig. 1 which may be entirely unrelated to the longer term trend from human activities.

    The other key issue is whether or not these wiggles have implications for what is known as climate sensitivity (i.e., the amplitude of the temperature response you get from some change in the global energy balance, a doubling of CO2 usually as an arbitrary standard). It is much more likely that it affects the nature in how we get there rather than the end result. There is no example of a simulation of internal variability through the coupled atmosphere-ocean system that abruptly produces “wiggles” on the scale of a doubling of carbon dioxide, so it is a very robust result that the warming influence of much higher CO2 levels will be realized eventually (the extra energy has to go somewhere). Note however that a doubling of CO2 is a type of forcing that far exceeds what we’ve seen over the Holocene, and in contrast the current signal is not that large (at least not overwhelmingly so) and so scientists are working on detecting a trend which has only begun over the last few decades to exceed the noise of natural variability.

    Comment by Chris Colose — 13 Jul 2009 @ 4:24 PM

  83. Thanks to RC for posting this even though in so many ways it seems in opposition to many of the views posted here.

    A while back, there was a threads with numerous posts debating whether we were cooling or not since 1998, 1999, 2000 – pick the year. And anyone that argued that we were cooling was declared to be a denier and were told the lower temperatures were natural variability and that any year now temperatures would be right back up to the 1998 level. Then there was the Keelyside post with, I believe, even a bet that we couldn’t be cooling.

    Now comes this article declaring that, indeed, perhaps we are in for 20-30 years of cooling or flat temperature, even with rising CO2. Twenty or thirty years – that is almost “climate”. Or, do we now need to redefine climate to something longer and these 20-30 year excursions can be called “climeather”?

    Comment by Jim Cross — 13 Jul 2009 @ 4:47 PM

  84. wayne davidson wrote in 77:

    Its swell to read Raypierre again on this site….

    #66, Timothy, the model animation in question use to be on this page:

    http://www.metoffice.com/research/hadleycentre/models/modeldata.html

    It showed 2007 similar ice minima in the year 2040 or so. My question remains, why they got it wrong?? Its a shame that they don’t display this animation again for a means of finding out just why they underestimated the melting so radically…

    Ask and Ye shall receive

    Comment by Timothy Chase — 13 Jul 2009 @ 4:57 PM

  85. Jim, those time spans refer to how much variability there is in the data and how many data points are needed to do the statistical tests to detect a trend.

    Remember “angry beast” — if the variability is increasing, the length of time needed to detect a trend also increases.

    Look at this, for example:
    http://scholar.google.com/scholar?sourceid=Mozilla-search&q=permanent+el+nino

    Comment by Hank Roberts — 13 Jul 2009 @ 5:10 PM

  86. # 81 (Susan),

    1) 1998 was a significant El Nino year which is why it shows up as such a spike. 1998 was one of the biggest, so its net effect (0.1-0.2 K) was among the largest and is easily identifiable visually on a plot of global Temperature vs. time, but it is also superimposed on the much larger (0.7-0.8 K) long-term trend. But the interest is not just *that year* but the impacts on the climate system *after* that year, perhaps even into present day.

    2) There are lots of news stories about anomalous cold and warm events (or even things like drought which may have more to do with precipitation/evaporation than temperature), hurricanes, floods, or what have you. The problem with climate change is that, when discussed correctly, it is not very news worthy. I say that because in the media there is a lot of focus on the “latest” and “up-to-the-minute” stories, whereas climate change is about longer-term statistics, which require a lot of stories being grouped together over extended periods of time to paint a certain picture. This is not really how the media communicates. You need to look past the stories about cold and warm events to see the direction the whole system is headed in on timescales of decades to centuries. This also requires abandoning the notion that a super hot day in January is global warming, and a cold day in July cancelled out global warming, as neither of those things are valid.

    Comment by Chris Colose — 13 Jul 2009 @ 5:11 PM

  87. Thanks to Ray, for the inline response way back at Comment #1 and for filling in for Kyle.

    So, Ray, I guess one question that’s bound to come up — I linked a few responses back to a search on “permanent El Nino” (a typical journal article title from that search is:
    “A permanent El Niño-like state during the Pliocene” )

    Can you tie the observations in this paper to that paleo work and suggest how the course of events might go if that’s where we’re going this time around, only much faster?

    I asked earlier if a significant prolonged El Nino would cause detectable increased infrared energy radiated away from the plane, not just a rearrangement of heat within the climate system? (Does El Nino pump heat mostly into the atmosphere to be rearranged, or does it pump heat significantly out into space?)

    I suppose someone is bound to suggest that El Nino is the mechanism Gaia uses, glaring heat rays from wide-irised eyes to cool off — do the models include a permanent El Nino condition for a long while, and what difference does it make in radiation going out?

    [Response: On a short time scale, the El Nino is a good example of how ocean circulation can cause a temporary change in ocean-atmosphere heat transfer by exposing more warm water to the air. One problem I have with "permanent el nino" as a mechanism for climate change is that the way the el nino warms the atmosphere is not sustainable. You eventually run out of energy. I had an interesting conversation on this subject with Ros Rickaby during my recent visit to Oxford, and another problem with "permanent el nino" is that it's hard to satisfy angular momentum balance if you permanently get rid of equatorial easterlies. Not impossible, but it's a hard state to make sense of. An interesting idea she has is that "permanent el nino" is not the disappearance of ENSO cycles, but rather a deepening of the thermocline so that ENSO has less expression in sea surface temperature. Makes a lot of sense to me. --raypierre]

    Comment by Hank Roberts — 13 Jul 2009 @ 6:03 PM

  88. “Now comes this article declaring that, indeed, perhaps we are in for 20-30 years of cooling or flat temperature, even with rising CO2. Twenty or thirty years – that is almost “climate”. Or, do we now need to redefine climate to something longer and these 20-30 year excursions can be called “climeather”?”

    I have a – probably naive – question that relates to this:

    Let’s suppose that there has been no significant increase in global cloud cover or any other natural factor which could reduce the total amount of solar heating in the last decade or so. In that case, all the additional CO2 in the atmosphere surely must have caused the Earth to warm up, so if we’re not seeing the warming in the global average temperature measurements for the last decade, that must just mean that we’re not measuring it correctly. It can’t mean that the Earth is actually staying the same temperature, because simple physics tells us that that additional heat must be going somewhere. Is that right?

    If we were just able to measure things more completely, would we ‘find’ that heat (maybe in warming of the deep ocean or somewhere else) and would the apparent pause in global warming then just disappear, with being able to see the complete picture? I’m not suggesting that Kyle’s paper is wrong, at all – if I understand it correctly, there is no contradiction between saying that: (a) the way heat is redistributed between ocean and atmosphere has had a genuine shift every few decades, and; (b) the Earth as a whole is warming constantly with no significant deviation from a long-term trend. It seems to me that without a substantial change in cloud cover or some other very obvious factor, (b) just has to be true, because of simple physics (a radiative imbalance in the Earth’s total energy budget, or whatever the correct terminology is).

    What do you think?

    If this is right then it seems to be a mistake to say or imply that we have had, or expect to have, a period of falling or constant global average temperatures – we should rather say that the heat is there in the climate system somewhere (like a pan on a stove that is slowly and steadily warming up) and that this heat will sooner or later manifest itself in any series of measurements in which we’re currently seeing an apparent cooling or levelling off. Presumably we would expect to see a corresponding rapid warming in due course as that series of measurements ‘catches up’ again to the long-term trend.

    Comment by Icarus — 13 Jul 2009 @ 6:10 PM

  89. Chris Colose #86,
    “But the interest is not just *that year* but the impacts on the climate system *after* that year, perhaps even into present day.”

    I have made this same argument on your blog, though you rejected it, saying,
    “Response– The 1998 El Nino is a spike. The long-term trend is due to radiative forcing, and there is very low probability of having the number of warmest years we’ve had in the last decade in a system characterized by just noise, but that changes when you introduce the trend– chris”

    I guess once the idea is presented in such a way that does not challenge your understanding of climate, it is acceptable.

    Comment by Carl Wolk — 13 Jul 2009 @ 6:12 PM

  90. #84 Thanks Timothy, is it possible that “A1B” scenario is way off?? As opposed to the animation model itself? The questions remain, finding out model or scenario failure reasons are important. In other words, do you have other animation scenarios out of your magic computer?

    Comment by wayne davidson — 13 Jul 2009 @ 6:20 PM

  91. My thanks to raypierre for his reply (#71) and also jkga, dhogaza, chris colose, as I write, and even the gentleman who thinks I’m a troll (which assuredly I’m not.) I’m interested in all of your responses but, in a way, they make my point for me. I’m sorry if I didn’t make myself clear enough, but the problem that I see is the mismatch between the message that is perceived by the wider public, and the reality of the climate science position, as so well presented in the replies that I mentioned.

    How many people do you think have the time or the inclination to go and find then read the Keenlyside paper, for instance? Or even understand it? I have a degree in physics, so I’m not completely unqualified to understand the issues in climate science, but I have friends – engineers, scientists, technologists – who mostly (not all) exhibit a high degree of skepticism about the “alarmism” (as they describe it) about global warming.

    These are intelligent people with a science background, but if even they (and sometimes me too, I’m afraid) are struggling to match up the story from the climate science with the way that the world is actually behaving around them, then that’s not actually their problem, it’s a climate science problem, because its message is confused or diluted or corrupted.

    I’ve actually found the article in this post very helpful, but I get the feeling that it’s preaching to the converted. It’s a receptive audience here at RC! … one that understands the science. But the common perception out in my community is that the world is certainly not warming, hasn’t been for some time, and that’s at variance with the models. I understand why averaging many models can mask the variance, but for most people the simple appeal of the averaged graphs trumps any explanations like the ones here. I could mention other objections that I hear, all of which you’d be able to dismiss with a scornful laugh, but the point is that dismissing them takes a level of comprehension that virtually none of the population have (who aren’t in the trade.)

    People (or at least the people that I know) need a message that fits their understanding. Not the simplistic “the earth is going up in flames” that we see in some of our press, nor highly technical discussions at the other end of the spectrum. They want a story that matches their intelligence and capability to absorb without having to go and search the scientific press.

    Most importantly, it has to match their understanding of what’s going on, climate-wise. And the ideas in Kyle Swanson’s article above could help a lot, but it needs to reach a much wider audience than the readers of RC who obviously understand it all already.

    As I re-read what I’ve written above, I see that I’ve probably tried your patience. Maybe RC isn’t the right place to raise the issue, but I’m sure that there is an issue, and it’s an issue that climate science in general will need to address if it’s to win the argument in the long term. If, as seems likely, there is a pause in global warming, then climate science will need to find a way to communicate that in a way that gently and authoritatively corrects the over-simplistic perceptions out there. Gently, because many people have become inured to the shrill voices of some commentators, and the resetting of expectations for a longer-term scenario will take some intelligent marketing.

    Comment by Alex — 13 Jul 2009 @ 6:27 PM

  92. So we seem to have climatus interruptus.Not surprising since most phenomena in nature don’t obey a constant relationship for very long. Kyle Swanson ends his post on an ominous note. “……the fact that humanity is poking a complex,non-linear system with GHG forcing-and that there are no guarantees to how the climate may respond.” We are indeed playing with fire.

    Comment by Lawrence Brown — 13 Jul 2009 @ 6:31 PM

  93. Carl (# 89),

    I don’t quite recall the context of our discussion, so just responding to your comment.

    It is very unlikely that in a stationary climate we would observe the recent cluster of warm years, most of which being the warmest in the instrumental time period (see Zorita, Stocker, and von Storch 2008). The “long-term trend” I don’t indicate to mean the last decade (even if there is a residual component from El Nino to a new cliamtic state, an idea that I don’t really take to, but I’m also not an expert here), but rather the much longer influence (say over the last 50 years) which is clearly due mostly to greenhouse gases and not El Nino.

    Comment by Chris Colose — 13 Jul 2009 @ 6:45 PM

  94. Hank 85 and 87

    Surely you are not suggesting that a permanent El Nino is lurking behind what may be a temporary downturn in temperature?

    Is there an official RC viewpoint on this post?

    See this post:

    http://www.realclimate.org/index.php/archives/2008/05/global-cooling-wanna-bet/

    Here is the bet proposed by RC:

    “The bet we propose is very simple and concerns the specific global prediction in their Nature article. If the average temperature 2000-2010 (their first forecast) really turns out to be lower or equal to the average temperature 1994-2004 (*), we will pay them € 2500. If it turns out to be warmer, they pay us € 2500. This bet will be decided by the end of 2010. We offer the same for their second forecast: If 2005-2015 (*) turns out to be colder or equal compared to 1994-2004 (*), we will pay them € 2500 – if it turns out to be warmer, they pay us the same. The basis for the temperature comparison will be the HadCRUT3 global mean surface temperature data set used by the authors in their paper.”

    Would RC still make that bet?

    [Response: Almost certainly yes. As an exercise for the reader calculate what the mean temperature anomaly would need to be for RC to lose the first part of the bet... - gavin]

    Comment by Jim Cross — 13 Jul 2009 @ 6:51 PM

  95. What about the second part of the bet?

    Comment by Jim Cross — 13 Jul 2009 @ 6:55 PM

  96. Hank, isn’t it the case that the various oscillations (ENSO, PDO, etc.) are simply re-arranging the energy fluxes within the climate system? Put another way, these oscillations have no effect on the long-term global energy budget. Or put yet another way, the final equilibrium temperature will be exactly the same with or without these transient oscillatory modes. Am I right?

    Comment by Jim Galasyn — 13 Jul 2009 @ 7:01 PM

  97. Seems to me that the new El Nino event will provide a nice test of the “pause” hypothesis outlined in the post above. GISTEMP noted in its review of 2008:

    Given our expectation of the next El Niño beginning in 2009 or 2010, it still seems likely that a new global temperature record will be set within the next 1-2 years, despite the moderate negative effect of the reduced solar irradiance.

    The El Nino is here, and while it’s not impossible that it might fizzle, the current expectation is that it will last into 2010. There are some intriguing possibilities: strong El Nino, new global temp record in 2010 (ie above 2005 GISS, 1998 HadCrut); moderate El Nino, new global temp record; moderate El Nino, no new record, etc etc. If we had a strong El Nino and no new record, that might suggest something along the lines of the “pause” hypothesis – and no doubt the usual suspects would make hay… Forgive me a shudder at the thought.

    Comment by Gareth — 13 Jul 2009 @ 7:15 PM

  98. Re: #91 (Alex)

    I agree that there’s tremendous room for improvement in how climate science is communicated to the public. RealClimate is top-notch, but doesn’t reach enough people to counter the very effective propaganda campaign attempting to deny the reality, human origin, and danger of global warming.

    I’m especially vexed by the perception by so many that there’s “proof” that “global warming has stopped.” This is based on faulty statistics (often by those who should know better, hence are not just mistaken but dishonest) and the truly silly, but pervasive, idea that global warming means every year should be hotter than the one before it. Anyone who reads my blog knows I work very hard to dispel these myths, but a lot remains to be done to communicate these sometimes not-so-simple truths to the voting public.

    In fact, perhaps Al Gore did a better job of it than the scientific community. But much of his efforts are negated by the mean-spiritied, dishonest, but effective character assassination aimed at him. Despicable, yes — but also effective propaganda.

    On topic: I’ve posted a comment on this post:

    http://tamino.wordpress.com/2009/07/14/warming-interrupted/

    Comment by tamino — 13 Jul 2009 @ 7:31 PM

  99. #70:

    Thanks Ike; excellent summary. I too am inclined to wonder about the current fad for ocean quasi-cycles. ENSO sure; but PDO/IPO, AMO, IOD etc etc? Seems the favoured “explanation” for this or that phenomenon correlates most closely with the domicility of the observer. Eg the way we’ve all got the hots for IOD in Australian hydrology at the moment (yeah, ugly pun, sorry).

    G.

    Comment by GlenFergus — 13 Jul 2009 @ 7:32 PM

  100. Raypierre (22):

    Thank you and I fully agree. I thought the Easterling paper, and Gavin’s similar analysis here earlier, regarding expected plateau periods within a longer term warming, were not only quite useful in providing rational justifications, but also quite interesting.

    Doug (29):

    I fully agree but that won’t stop the deniers from screaming anyway.

    Comment by Jim Bouldin — 13 Jul 2009 @ 7:47 PM

  101. Alex, I’m a musician and sometime academic by trade, innocent of any mathematical background more advanced than Algebra 2.

    However, I find 2 criteria are largely sufficient to decide where the balance of credibility lies in this climate “debate.”

    1) Who is telling a self-consistent story, and who is merely picking nits, wherever they can be found or imagined? (Hint: the idea–a la Monckton–that warming on Mars “proves” Terrestrial warming to be solar in origin is not logically consistent with the idea that all Terrestrial warming is an artifact of UHI.)
    2) Who is responding constructively to opponents’ points, and who is content to cut-and-paste ad nauseam, no matter how many times an argument may have been answered? (Hint: the “saturated gassy” argument was made at the turn of the century–20th century, that is–and has definitely been shown incorrect since the days of Gilbert Plass’s climate research in the 1950′s. Yet it is so distinctly “undead” in the blogosphere that RC has devoted a whole post to it.)

    In short, behavior–tactical behavior, if you will–is enough to reveal who is really investigating and who is just debating.

    On a related topic, I think pessimism about the state of the public perception of the debate is understandable but ultimately unwarranted. We’ve had the survey numbers swinging the wrong way for a bit, but that’s short-term. The numbers swung pretty seriously our way with AIT; there was bound to be some rebound. Then we got the slightly cooler 2008 temps for denialist talking points.

    But the denialosphere are rapidly finding out that you can only claim it is cooling for so long before people start to wonder why we’re at the same historically high anomalies we’ve been experiencing throughout the decade; why the sea ice hasn’t really recovered; why droughts are getting worse; and so on.

    Comment by Kevin McKinney — 13 Jul 2009 @ 8:12 PM

  102. “As an exercise for the reader calculate what the mean temperature anomaly would need to be for RC to lose the first part of the bet…”

    Ooh! Ooh! I’ll play! I make it -0.67ºC (using GISTEMP), about 1.3ºC cooler than 2008, and lower than any year in the GISTEMP record. I would definitely take the bet.

    [Response: I think you may have miscalculated - it's not quite that bad. For the HadCRU3Tv data, I calculate that the mean anomaly from Jun 09 to Oct 10, would need to be 0.014 dec C or less. No year has been that cold since the early 1980s and no month that cold since the immediately post-Pinatubo years. - gavin]

    Comment by CTG — 13 Jul 2009 @ 8:35 PM

  103. Swanson publishes (see the first paper in the post above)

    “These (124) shifts were accompanied by breaks in the global mean temperature trend with respect to (125) time, presumably associated with either discontinuities in the global radiative budget due (126) to the global reorganization of clouds and water vapor or dramatic changes in the uptake (127) of heat by the deep ocean.”

    Well, that seems perfectly reasonable. These huge oceans systems, capable of storing immense amounts of heat, wobble a bit and takes up the incoming inbalance for a while and hides it below the waves. Air temps remain steady. Am I missing something?

    Comment by Mike#22 — 13 Jul 2009 @ 8:47 PM

  104. Jim, I really don’t know — serious question on my part, I don’t know if the tools we have allow measuring the planet’s outgoing heat. I think we don’t have any instruments far enough away, like Triana was meant to be.

    [Response: Triana would not have helped. Triana would have given you full-disk albedo, but would have done nothing for the infrared side of the budget. --raypierre]

    Comment by Hank Roberts — 13 Jul 2009 @ 8:50 PM

  105. #103 Mike, Makes sense except the current oceans look kind of warm:

    http://www.osdpd.noaa.gov/PSB/EPS/SST/climo&hot.html

    So what about this pause? Has there been a warming exchange block at the interface between ocean and air?

    Comment by wayne davidson — 13 Jul 2009 @ 9:14 PM

  106. Hank, it’s a very good question, which I’ve often pondered. My thinking has been that these oscillations are part of the atmospheric overturn that gives us a well-mixed atmosphere, which lets us talk about global average surface temperature.

    But I think that the best way to think about the problem is to look at the final equilibrium state. The trajectory to the final state will have lots of wiggles and oscillations, but ultimately the planet must achieve radiative equilibrium with space, and no pauses/episodes will prevent this.

    [Response: No, I don't think so. The atmosphere has too little mass to give you much thermal memory on time scales of more than a month or two. If you want to find something that persists for a decade or more, and is not a response to an external forcing like increase of CO2, then you need to look to the oceans. --raypierre]

    Comment by Jim Galasyn — 13 Jul 2009 @ 9:54 PM

  107. @73 dhgozza
    Wiggle also known as “wobble” by hurrican movement.

    @81 Weather patterns are wrong all over the world, its not just brazil which miss winter, the europeans still wait for the summer.

    Thawing permafrost and released methane clathrates this is what is going to make it worse now, despite any efforts the coming century.
    We have underlying warming of “~2.4C” and the biggest contributions are still in the pipeline.

    We have to act faster!

    @83 The weather is in flux, due to the fact of missing climate balance.

    Comment by save gaia — 13 Jul 2009 @ 10:34 PM

  108. Ray, thanks for the help. Is my second point about equilibrium correct, i.e., oscillations like ENSO and PDO won’t change the final temperature? Would it also be correct to say that they won’t delay the arrival of the final temperature?

    Comment by Jim Galasyn — 13 Jul 2009 @ 10:42 PM

  109. Raypierre in response to Phil. Felton at #46 13 Jul 2009 at 8:59 am:

    …this points up a common misconception about the operation of climate. Though we speak of “thermal inertia,” it’s not really inertia in the sense of Newtonian mechanics. If you start a warming trend by increasing a climate warming forcing and then zeroing it out, it does not (unlike a body in notion) tend to keep on warming unless you do something later to stop it. Warming is a damped response to the current forcing, and the minute you zero out the forcing, the trend will turn the other way. “Committed warming” is only committed because the scenario there is not zeroing out the GHG forcing, but rather freezing its value, giving the climate time to catch up. In this sense, the dynamics of climate change is more Aristotelian than Newtonian.

    I am not sure how common this misconception of climate is, and I obviously can’t speak for Akasofu, but I do know that it’s not a misconception I have myself here.

    In the little ice age, as I understand it, temperatures fell gradually over a number of centuries to correspond in some as yet unexplained way with the “Maunder Minimum,” a period of reduced sunspot activity. It seems fairly reasonable to suppose that had humans emitted no CO2 at all, temperatures would have risen again anyway in the same pattern that they had fallen previously, i.e. gradually and over a number of centuries. Even the IPCC2007 has said somewhere, I believe, that the levels of CO2 were probably not high enough until about 1950 to have had much effect on the global average temperature. So I am having a lot of trouble in understanding how, in the Swanson & Tsonis theory, these authors can genuinely believe in an underlying “true forced warming signal” from GHG emissions that began 1850 and continues today.

    Comment by Alex Harvey — 13 Jul 2009 @ 11:31 PM

  110. The choice of 1979-1997 might not have been intended as cherry-picking, but it is unfortunate choice nonetheless. This term is too short for an accurate slope, and it makes the regression way too sensitive to the 1992-1993 temperatures, which were influenced by the Pinatubo eruption. If you take 1970-1997 in GISTEMP (I didn’t try HADCRUT), and leave out the outliers 1992 and 1993, and do a linear regression, then there is no need to assume a pause at all. And you get a slope of 0.016 degrees per year, which seems more realistic than the 0.01 or so obtained in the regression above.

    This does not mean that the pause isn’t possible. But unless the authors come up with a more specific mechanism and data as to where the overshot heat is coming from, I have more confidence in my own regression than in the one posted above.

    Comment by Alex De Visscher — 14 Jul 2009 @ 12:13 AM

  111. Link to the ‘cooling’ graph Al Gore has been asked to explain while visiting Australia
    http://www.news.com.au/story/0,27574,25780407-5019059,00.html

    [Response: That's funny. The implicit transient climate sensitivity in that graph is over 6 deg C for a doubling of CO2 (i.e. that is what would have to be the case for the two scales in CO2 and temperature to be commensurate). Given that IPCC estimates TCR (this is not at equilibrium of course) are around 2 deg C, this is at least a factor of three misleading. Not likely to convince anyone who knows anything about it. - gavin]

    Comment by Johnno — 14 Jul 2009 @ 12:36 AM

  112. Alex says: 13 July 2009 at 2:44 PM

    Well, to this simple observer of the AGW scene, all of the AGW predictions, viewed as monotonically climbing graphs, show exactly the opposite of what dhogaza claims. And skeptic friends tell me that the inability of the models to predict anything other than monotonically climbing temperatures is why there’s been a rebranding of AGW as “climate change”. It seems a pity that the models seem unable to take into account significant ocean cycles, solar cycles, etc. To the simple observer it seems either that the models are inadequate or that there’s been a failure to communicate the realities of AGW

    This is an excellent example of why averaging together dozens of differently perturbed model runs(1) is an explanatory disaster, even though it yields superior predictions over the long haul. Such averaging smooths out the ‘weather’ which the climate models do simulate.
    To get an idea of how big a difference this can make – see the first figure in this post, and compare any individual colored line with the smooth black line which is the average of the 55 realizations.
    RC has been showing this sort of thing from time to time, but the vast majority of less technical sources of climate news seldom or never show graphs like that.
    Smoothing is very powerful, but there’s a kind of information it always destroys; it makes the viewer ignorant of how much noise the signal must compete with.
    (1) This is roughly true whether the multiple runs are made with the same model, or different models, or if each of many models is run with many different perturbations and then all are averaged together, or if each ensemble is averaged separately, before being averaged to achieve the final result..

    Comment by llewelly — 14 Jul 2009 @ 2:28 AM

  113. Jim, #96, that’s my reading of this too.

    Comment by Mark — 14 Jul 2009 @ 2:38 AM

  114. “But the common perception out in my community is that the world is certainly not warming, hasn’t been for some time, and that’s at variance with the models.”

    Then you’re being trolled by your community.

    This could be selection bias. Since they don’t like the idea of AGW (for various emotional reasons) and they see themselves being bombarded with “Global Warming” from the left-wing news (though the right-wing news tells them the *real* truth…) they remember each winter day there was snow, just like they had in the past (forgetting that there were more snow days in the past) and they remember each summer day that turns out miserable (forgetting that there have been days hotter than before too).

    Is your community in a coal-mining area?

    Comment by Mark — 14 Jul 2009 @ 2:49 AM

  115. “In fact, perhaps Al Gore did a better job of it than the scientific community. But much of his efforts are negated by the mean-spiritied, dishonest, but effective character assassination aimed at him. Despicable, yes — but also effective propaganda.”

    I believe only effective propaganda for those predisposed to accept it. Or for those who are surrounded by those who believe it and, in an effort to conform (odd, given how many like to pose as maverick “skeptics”) agree at that time with the propaganda.

    Comment by Mark — 14 Jul 2009 @ 2:57 AM

  116. andy #80, 35000 europeans died one summer of heatstroke.

    If you take that as your definition of “cooking” us, then it’s happening.

    Comment by Mark — 14 Jul 2009 @ 3:03 AM

  117. Dea RC, is the warming linear in nature over just a decade or two or over a century or more. Our present age of AGW has a large cooling part (probably local as opposed to being global) but its having a masking effect. Is this effect keeping present decadal warming trends linear but if we clean up our pollution but fail to drop our CO2 emissions by much mean an increased linear warming trend or a more non linear one ?

    Comment by pete best — 14 Jul 2009 @ 4:23 AM

  118. Re: #5

    [Response: Wayne, please note that this is Kyle's article not mine, though I did encourage him to write it for us. I think the interesting question raised (though not definitively answered) by this line of work is the extent to which some of the pause in warming mid-century might have been more due to decadal ocean variability rather than aerosols than is commonly thought. If that is the case, then a pause or temporary reduction in warming rate could recur even if aerosols are unchanged. Learning how to detect and interpret such things is important, lest a temporary pause be confused with evidence for low climate sensitivity. --raypierre]

    By George, I think they’ve got it. Quite how it’s managed to escape so many for so long that ocean variablility rather than aerosols is the likely cause of mid-20th century cooling (or lack of warming) is totally beyond me.

    I hope Hank Roberts and Tamino are reading this as I’ve taken considerable flak from them over my continued assertion that there is no way that aerosols could have been responsible and that ocean circulation was the place to start looking.

    Of course it does mean that the IPCC “detection and attribution studies” are based on flawed assumptions. It’s also the case that if ocean variability caused the cooling, then it’s likely that it caused (or amplified) the 1910-1940 warming of ~0.13 deg per decade and similarly amplified the post-1975 warming. The implication being that the CO2 signal is much reduced.

    Ray – Just one question, though. If there is a pause. What happens to all the “heat in the pipeline”?

    Comment by John Finn — 14 Jul 2009 @ 4:59 AM

  119. Alex Harvey writes:

    Dr. Shunichi Akasofu has made exactly the same point, except that the latter has attributed the same trend to recovery from the Little Ice Age rather than GHG forcing.

    As I have said many times, Akasofu-san wa bakayaro des’. What is the physical mechanism behind “recovery from the Little Ice Age?” “Recovery from the Little Ice Age” isn’t a process. Does he think the climate is like a spring in simply harmonic motion? It isn’t.

    And given that there wasn’t enough CO2 in the mid-nineteenth century to be causing the same warming as there was in 1975 it seems rather strange to me to be attributing a single linear trend all the way from 1850 until 1997 to GHGs without any mention of the warming trend that already existed in 1850. Has this analysis been simplified?

    No, but a simple analysis shows the intimate connection between the temperature rise and the CO2:

    http://BartonPaulLevenson.com/Correlation.html

    Comment by Barton Paul Levenson — 14 Jul 2009 @ 5:54 AM

  120. Rob writes:

    “Also shown is a linear trend using temperatures over the period 1979-1997 (no cherry picking here…””

    Unless you’re cherry picking a linear trend ?!

    A linear trend is ALWAYS the default in statistics unless you can show that a more complicated relationship is statistically valid. Occam’s Razor.

    Comment by Barton Paul Levenson — 14 Jul 2009 @ 5:56 AM

  121. Gareth writes:

    The El Nino is here, and while it’s not impossible that it might fizzle, the current expectation is that it will last into 2010. There are some intriguing possibilities: strong El Nino, new global temp record in 2010 (ie above 2005 GISS, 1998 HadCrut); moderate El Nino, new global temp record; moderate El Nino, no new record, etc etc. If we had a strong El Nino and no new record, that might suggest something along the lines of the “pause” hypothesis – and no doubt the usual suspects would make hay… Forgive me a shudder at the thought.

    I’ll bet you anything you want that as early as 2013 we’ll be hearing the deniers say “Global warming stopped in 2010!”

    Comment by Barton Paul Levenson — 14 Jul 2009 @ 6:09 AM

  122. A minor nitpick: “an objective criteria” should be “criterion”.

    How real is this “pause” in warming anyway? In response to some inactivist stuff here in Australia, I downloaded the HadCRUT3 data and did a linear regression for 1995-2008 (the period for which they were claiming there was no longer an upward trend) and found they were wrong, though the upward trend is a lot smaller than the long-term trend (your green line). Given that over this period we’ve had (1) a strong El Niño early on, (2) more recently a big La Niña and (3) the solar cycle has recently bottomed out a relatively low point, is it really surprising that the trend appears to have “paused”?

    How much of the slowdown in increase over the last few years can be explained by the solar cycle? To me it seems pretty significant that we are still close to all-time highs despite all 3 of these natural temperature influences that should have been pointing down the last few years.

    If the solar cycle peaks in 2013, isn’t there a good chance that even if this paper is correct in terms of the big picture, we will see a short-term peak crossing your red line around about then?

    Comment by Philip Machanick — 14 Jul 2009 @ 7:01 AM

  123. Alex @91, I’m afraid that the lesson here is that reality isn’t as simple or as accommodating as people want it to be. And since science is about truth, the science has to reflect the truths that we cannot overconsume with impunity and that we are messing with a very complicated system on which our welfare depends. There’s a limit to how much we can dumb things down. Maybe it’s the public that needs to wise up.

    Comment by Ray Ladbury — 14 Jul 2009 @ 7:10 AM

  124. I’m Irish and a greenie (and by that I don’t mean leprechaun green).
    But I do have that strange logic that the Irish are rumoured to have – as in the often told tale of the Irishman, asked by a tourist, how to get to Killarney, replied “If you want to get there you shouldn’t start from here”.

    And my odd logic is that as I am concerned about AGW, I actually _want_ to see higher temperatures(see below).

    So I’m worried about climate change and global warming. But as the temperatures over the last ten years or so have more-or-less leveled and have not been rocketing smoothly up, and there now may be a decade’s worth of pause in global warming, so I am crossing my fingers that soon the temperatures will start rising again, just to show sceptics that AGW is real. All this, when as a greenie, or anyone else for that matter, what I would like to see is, of course, global cooling. And given global cooling I could then ditch my stupid little 1000cc Fiat runabout and get that vast new 5.7litre Jaguar XJ4 that I secretly covet and burn a bit of rubber, so as to impress my neighbour who has a big BMW, also a 4×4 (for her dog, he says!), a powerboat, two patio heaters and a ride-on grass mower.

    Point is, when the temperatures are not doing “what they are meant to do” it is hard to deal with sceptics who suggest that within climate variability there is a hidden downward trend. And only a rise soon will do that.

    Comment by Theo Hopkins — 14 Jul 2009 @ 7:14 AM

  125. There was a reference above to my piece examining whether climate campaigns can survive a cooling test. Here are relevant links (shortcuts)
    http://bit.ly/dotCool2
    http://bit.ly/dotCool

    Comment by Andy Revkin — 14 Jul 2009 @ 7:25 AM

  126. “so I am crossing my fingers that soon the temperatures will start rising again, just to show sceptics that AGW is real. ”

    Only if the underlying process is that there isn’t a problem being stored up for us in future.

    False sense of security.

    Comment by Mark — 14 Jul 2009 @ 7:58 AM

  127. Jphn Finn 118: Whut?

    The ocean is a resevuir of heat.

    It doesn’t create any itself.

    The sun does that (and a very minor geothermal component). And that is affected by the aerosols.

    False dichotomy on your reading of others postings.

    Comment by Mark — 14 Jul 2009 @ 8:15 AM

  128. Re #111
    Link to the ‘cooling’ graph Al Gore has been asked to explain while visiting Australia
    http://www.news.com.au/story/0,27574,25780407-5019059,00.html

    [Response: That's funny. The implicit transient climate sensitivity in that graph is over 6 deg C for a doubling of CO2 (i.e. that is what would have to be the case for the two scales in CO2 and temperature to be commensurate). Given that IPCC estimates TCR (this is not at equilibrium of course) are around 2 deg C, this is at least a factor of three misleading. Not likely to convince anyone who knows anything about it. - gavin]

    Also it would be more appropriate to plot ln(CO2) anyway.

    Comment by Phil. Felton — 14 Jul 2009 @ 8:15 AM

  129. Thanks for the great scientific view on this topic. I would guess the temperatures will again begin to increase. However, maybe some of our efforts to curb global warming are paying off. Time will tell.

    Comment by Tommy — 14 Jul 2009 @ 8:38 AM

  130. John Finn:

    By George, I think they’ve got it. Quite how it’s managed to escape so many for so long that ocean variablility rather than aerosols is the likely cause of mid-20th century cooling (or lack of warming) is totally beyond me.

    I hope Hank Roberts and Tamino are reading this as I’ve taken considerable flak from them over my continued assertion that there is no way that aerosols could have been responsible and that ocean circulation was the place to start looking.

    This is a total misreading of Raypierre’s comment.

    Sheesh.

    [Response: Quite so. I was only suggesting a reconsidering of the relative roles of aerosols and ocean decadal fluctuations. I wouldn't presume to know the answer, and even once we do know the answer aerosols are virtually certain to be an important part of the story, given what we know for certain regarding the radiative effect of aerosols, which is indeed something. --raypierre]

    Comment by dhogaza — 14 Jul 2009 @ 8:41 AM

  131. Whoah — look at the two captions on Fielding’s image.
    (cut off in the link at the newspaper, oh oopsie, how could they?)

    Here’s the image with the caption showing at Fielding’s page:
    http://www.stevefielding.com.au/images/uploads/The_global_temperature_chart_thumb.jpg

    Right side caption describes the red line is _temperature_anomaly_.
    (Note where the zero level is — the red line is always above it.)

    Black text at bottom claims the red line is _temperature_ change, but — WTF??

    Comment by Hank Roberts — 14 Jul 2009 @ 8:50 AM

  132. re Alex #109

    In the little ice age, as I understand it, temperatures fell gradually over a number of centuries to correspond in some as yet unexplained way with the “Maunder Minimum,” a period of reduced sunspot activity. It seems fairly reasonable to suppose that had humans emitted no CO2 at all, temperatures would have risen again anyway in the same pattern that they had fallen previously, i.e. gradually and over a number of centuries. Even the IPCC2007 has said somewhere, I believe, that the levels of CO2 were probably not high enough until about 1950 to have had much effect on the global average temperature. So I am having a lot of trouble in understanding how, in the Swanson & Tsonis theory, these authors can genuinely believe in an underlying “true forced warming signal” from GHG emissions that began 1850 and continues today.

    That’s not really correct Alex. The anthropogenic contribution to atmospheric CO2 was a rise from around 280 ppm preindustrial to 310 ppm around 1940 [*]

    It’s very easy to calculate that within a climate sensitivity near 3 oC of warming per doubling of atmospheric CO2 (the median value from a large range of empirical analyses as described by the IPCC), that this should give a warming near 0.45 oC at equilibrium. Since the period of this rise in atmospheric CO2 was long, we can assume it came nearly to equilibrium by your date of 1950. Let’s say that the real warming contribution was 0.35 oC (0.1 in the pipeline that was realised post-1950).

    Pretty much the largest published difference in temperature between the bottom of the LIA and the mid 20th century is in the paleoreconstruction of Moberg et al. [**] This is around 0.6 oC rise in temperature in the Northern hemisphere. It seems likely that the cold of the LIA was predominantly in the N. hemisphere, but let’s say for the sake of argument that the world was globally cooler by 0.6 oC at the bottom of the LIA compared to the mid 20th century.

    In other words 50% or more of the warming since the bottom of the LIA to the mid 20th century is expected to be due to anthropogenic greenhouse forcing. The other contributions to the LIA cold (highish volcanic activity, low solar activity) likely account for the rest (0.25-0.35 oC) of the reduced temperature, and this is the amount that the earth might have warmed following reversal of the negative solar/volcanic forcing. [The N. hemispheric nature of the LIA might also have had a contribution from reduced ocean current heat flow to the high Northern latitudes (evidence for reduced Gulf stream flow during this period)].

    So the Swanson & Tsonis theory “an underlying “true forced warming signal” from GHG emissions that began 1850 and continues today”, is a pretty robust expectation from our understanding of the greenhouse effect and detailed knowledge of the atmospheric CO2 concentrations in pre-1850 to the present.

    [*]D. M. Etheridge et al (1996) “Natural and anthropogenic changes in atmospheric CO2 over the last 1000 years from air in Antarctic ice and firn J. Geophys Res. 101, 4115 -4128

    [**] Moberg, A et al. (2005) Highly variable Northern Hemisphere temperatures reconstructed from low- and high-resolution proxy data Nature 433, 613–618 (2005)

    Comment by chris — 14 Jul 2009 @ 9:32 AM

  133. Could we have a guest post from Anastasios Tsonis? – he seems to tell a slightly different story:

    Now the question is how has warming slowed and how much influence does human activity have?
    “But if we don’t understand what is natural, I don’t think we can say much about what the humans are doing. So our interest is to understand — first the natural variability of climate — and then take it from there. So we were very excited when we realized a lot of changes in the past century from warmer to cooler and then back to warmer were all natural,” Tsonis said.
    Tsonis said he thinks the current trend of steady or even cooling earth temps may last a couple of decades or until the next climate shift occurs.

    http://www.wisn.com/weather/18935841/detail.html

    Maybe Tsonis was misquoted :-)

    [Response: Tasos is a good scientist and quite reasonable person. I won't speak for him, but I sense from conversations I've had with him that he feels that many of his comments were taken out of context, or otherwise misrepresented. And perhaps he might have phrased things differently in hindsight. Tasos: if you happy to be reading this, we'd love to hear from you. --mike]

    Comment by Paul Biggs — 14 Jul 2009 @ 10:25 AM

  134. Re: #127

    Mark says:
    14 July 2009 at 8:15 AM

    Jphn Finn 118: Whut?

    The ocean is a resevuir of heat.

    It doesn’t create any itself.

    I know. But that heat can be ‘re-distributed’, so that more heat is released into the atmosphere during some periods than others. A bit like a drawn out ENSO event.

    PS are you trying to set some sort of record for the number of typos?

    The sun does that (and a very minor geothermal component). And that is affected by the aerosols.

    False dichotomy on your reading of others postings.

    Comment by John Finn — 14 Jul 2009 @ 10:46 AM

  135. #5 Raypierre response

    If ocean variability caused the cooling, this suggests to me that the ocean can operate somewhat like the Lindzen iris, although on a time frame of decades. Doesn’t this call into question the long-term predictions of temperature rise if the ocean periodically interrupts the rise by dissipating the heat?

    Comment by Jim Cross — 14 Jul 2009 @ 11:04 AM

  136. #131 Hank, quite distressing to see that oz people are subjected to this graph.
    Again, Hadley has something wrong in their system, what it is I don’t know. But not including vast swats of Arctic anomalies don’t help…. 2005 was the warmest year in history, this graph seen alone, suggests that the great melt occurred in 1998….

    but

    http://www.metoffice.gov.uk/climatechange/science/monitoring/hadcrut3.html

    Hadley doesn’t look so bad taken completely….

    Comment by wayne davidson — 14 Jul 2009 @ 11:41 AM

  137. Roger Pielke Sr doth pontificate on this “weblog”:

    http://climatesci.org/2009/07/14/failure-of-real-climate-to-respond-to-the-weblog-real-climate-permits-the-continued-presentation-of-misinformation/

    Comment by SteveF — 14 Jul 2009 @ 12:10 PM

  138. Wayne, there’s a very good reason for removing the artic.

    There aren’t many stations up there AT ALL.

    Definitely not enough to properly cover that expanse.

    So HC leave it out.

    GISS leave it in and interpolate.

    Either can look bad if you want to see it that way.

    Comment by Mark — 14 Jul 2009 @ 12:21 PM

  139. jonh finn, the typos aren’t an attempt to get a record. I just don’t care about impressing you.

    PS isn’t that actually an ad-hom? Sort of “you’re spelling is wrong, so your argument is wrong”.

    PPS lots of others say the same thing: you got it completely wrong and you did so by (assuming you aren’t being deliberately malicious, so if you don’t like it, we can go there if you like…) by misreading a statement into saying what you want it to say.

    Comment by Mark — 14 Jul 2009 @ 12:24 PM

  140. Roger Pielke Sr doth pontificate on this “weblog”

    As does his son, who apparently doesn’t understand that RC simply gave Swanson a soapbox from which to discuss his controversial paper.

    Comment by dhogaza — 14 Jul 2009 @ 12:37 PM

  141. Ray, I’m puzzled why Triana’s instruments wouldn’t help:

    http://www-pm.larc.nasa.gov/triana/documents/Huang_triana_toronto.pdf

    Did they pick the wrong bands to be useful, or what? Since the instrument’s still in the warehouse, what should be in board that isn’t, to track the information relevant to this topic?

    [Response: Among other things, infrared comes out of the nightside, not just the dayside. Triana only looks at the sunlit side of the planet, and may be suitable for process studies, but is not suitable for doing global energy balance. But even if you had satellites in the right orbit, getting long-term instrumental stability to a level where you could detect the relatively small imbalances caused by ocean/atmosphere heat exchange would be difficult. Hansen and others argue that direct in situ monitoring of ocean heat storage, while also difficult, is less so. --raypierre]

    Comment by Hank Roberts — 14 Jul 2009 @ 12:38 PM

  142. SteveF: Roger Pielke Sr doth pontificate on this “weblog”…

    It’s always amusing to see this at the end of Roger’s posts: “Sorry, the comment form is closed at this time.”

    Comment by Jim Galasyn — 14 Jul 2009 @ 1:18 PM

  143. “the extent to which some of the pause in warming mid-century might have been more due to decadal ocean variability rather than aerosols than is commonly thought. If that is the case, then a pause or temporary reduction in warming rate could recur even if aerosols are unchanged” – raypierre

    If it is the case, then how much of the warming in the ’80′s and 90′s was due to the positive phases of the AMO and PDO and how much will this reduce the figure for the sensitivity of the climate to co2?

    [Response: Not at all, because climate sensitivity cannot be reliably deduced from the late 20th Century record. This does not change that. - gavin]

    I assume the debate will now be opened to ask just what are the phenomena behind the natural oscillations which can overcome the forcing of climate by co2 – yes?

    Comment by stroller — 14 Jul 2009 @ 1:24 PM

  144. This discussion was way past due. I commend RC for objectively posting it, and the reasonable arguments that followed. The pursuit of truth will eventually be rewarded by gestalt.

    Comment by G. Karst — 14 Jul 2009 @ 1:27 PM

  145. This is purely and simply fitting the data to the story rather than letting the data tell the story. Bad science. Period.

    [Response: You are being quite unfair. Science has many routes to the truth. Ultimately, one needs to have models that proceed from basic physics, and if you look at Kyle's voluminous work on geophysical fluid dynamics, you'll see that he has plenty of that. Still, data analysis that attempts to identify cycles in data is a tried-and-true way to scare up suggestions of things to look for in the physical modelling. --raypierre]

    Comment by Steve — 14 Jul 2009 @ 1:46 PM

  146. Steve, 145, how do you test whether your story is correct WITHOUT trying to make it fit the data? And when it doesn’t fit the data, working out how to make it fit shows where other things may be working into the picture.

    E.g. if the graph is generally going up and there’s one peak (1998) and a trough (2007?) high up above the line and low down below it, would one way to work this problem out be to do something like this:

    What is the “shortfall”/”excess”?

    Now what happened at that time?

    Is that enough to cover the shortfall/excess?

    If it is, maybe you have the answer.

    Comment by Mark — 14 Jul 2009 @ 2:45 PM

  147. Ray, thanks for all the inline comments (and I hope people are going back and reading them).

    And thanks for the mention of Dr. Rickaby’s work.
    This paper for example describes changes in plankton over long climate cycles. This is wonderful stuff.
    http://dx.doi.org/10.1016/j.epsl.2006.10.016

    Comment by Hank Roberts — 14 Jul 2009 @ 2:52 PM

  148. What happens if we stretch this pause in global warming out to 2020, then look at the 30 years of real and predicted temperature data ending in 2020 (or 40 or 50 years)? Would that data provide a statistically significant warming trend?

    I know the preference is for much longer trends in temperature data (though I guess not 15,000 year long trends), but a lot of work I’ve read here talks about 30-50 year trends as being significant (e.g. the Antarctic Warming/Cooling debate).

    I’m sure what to make of the idea that we might,at some point in time, have statistically significant evidence of no warming over a reasonably long time frame.

    Comment by Colin — 14 Jul 2009 @ 4:51 PM

  149. Chris Colose (if you’re still around):
    Thanks for the response. It appears I didn’t make myself clear. Perhaps I should have used my full name (Susan Anderson); I understand and agree with – if only through a glass darkly due to my educational deficiencies – the points you made. I was trying to say that even taking the false premises of the denialosphere into account, their argument falls down on the obvious. Visually, 1998 sticks out like a sore thumb. And despite some cool temps, there are plenty of hot ones, as well as extreme events. My point was that while I don’t give local weather much weight, in the aggregate even a short-term argument falls down if the viewpoint is slightly expanded to include the whole planet and ups as well as downs. I know that climate is most accurately understood in the context of longish intervals; that too is distorted by the false premisites by selectively using millions of years when it suits their purpose.

    This is not meant to distract from the more learned arguments made here, to which my comment is only a small footnote. I hope noone takes it amiss; I learn all the time.

    Propagandists’ assume the purpose of science is to proselytize because they do so and assume their limitations extend to those with whom they take issue.

    Comment by susan — 14 Jul 2009 @ 4:52 PM

  150. Ray Ladbury @ 123.

    I’m afraid that the lesson here is that reality isn’t as simple or as accommodating as people want it to be. And since science is about truth, the science has to reflect the truths that we cannot overconsume with impunity and that we are messing with a very complicated system on which our welfare depends. There’s a limit to how much we can dumb things down. Maybe it’s the public that needs to wise up.

    And yet, and yet I can’t help thinking there’s a way of saying exactly that, and saying it in a way that actually penetrates. There probably won’t be sufficient “wising up” until that message gets through. For starters, the sentences probably need to be less sophisticated, very pointed, and easily remembered and repeated. Not easy.

    And there is no doubt some cultural expectation (exemplified in Einstein’s quote: “If you can’t explain it simply, you don’t understand it well enough.”) that if the problem were really significant, the necessary explanations would already be made to all political bases. The problem is that you’d practically need a whole army of sophisticated popularizers working full time to cut through the currrent pandemic of message clutter.

    Comment by Radge Havers — 14 Jul 2009 @ 7:33 PM

  151. Phil. Felton says:

    “And what caused that ‘recovery’?”

    One common misconception is that the thing that caused the little ice age recovery does not need to be something that has since been zeroed out.

    Comment by Bill Hunter — 14 Jul 2009 @ 8:21 PM

  152. Yeek!

    http://blogs.nature.com/climatefeedback/2009/07/unknown_climate_culprit_for_pa_1.html

    Comment by Hank Roberts — 14 Jul 2009 @ 8:22 PM

  153. Warming Interrupted? Seas responsible?? Well , June just past was 2nd warmest in history, with the southern Hemisphere being 2nd warmest as well… A contradiction?

    http://data.giss.nasa.gov/gistemp/tabledata/SH.Ts.txt

    So I await some convincing conviction statement on this temperature pause. Seems that current El-Nino is poised to surpass 1998 one, if this trend holds, Global temperatures may be highest in history soon.

    Comment by wayne davidson — 14 Jul 2009 @ 8:44 PM

  154. In the discussions of global warming and global cooling, are we confusing heat with temperature? The annual mean land and sea surface TEMPERATURES (which CAN be measured)appear to be being used as a proxy for the total HEAT of the global atmospheric and oceanic system (which cannot be measured directly). But could you not have a significant increase in the total heat gained by the system at the same time that the GISS and Hadcrut land/SST measurements are coming in slightly lower?

    For example, in a strong La Nina as we have just had, if colder water is being drawn up to the ocean surface, it would also transfer heat from the lower atmosphere to lower waters. But the SST would still be lower than normal. Would this lower temp. at the surface result in lower radiation out from the surface to the upper atmsophere, resulting in less heat lost to space and more heat retained by the system?

    Also, if there were to be a significant amount of melting of land glaciers and Greenland and WAIS ice in the same year, could the higher amounts of heat energy held in by GHGs be “hidden” by the heat of fusion in converting solid to liquid water? In other words, is it possible that during La Ninas and/or times of significant planetary ice loss, the surface temps would be going down while the total heat energy of the oceans is going up, with climatic results to become apparent later?

    Or, am I just confusing ignorance with insight? Thanks.

    Comment by Hank Smith — 14 Jul 2009 @ 9:30 PM

  155. I think the period 1998-2009 looks remarkably like the period 1950-1965, after which warming resumed.

    Comment by nigel jones — 14 Jul 2009 @ 10:54 PM

  156. You identified a breakpoint in the dataset at 1997. I analysed the HadCRUt3 simplified dataset (monthly data http://hadobs.metoffice.com/crutem3/diagnostics/global/simple_average/monthly) and identified three breakpoints in the dataset one at 1977, one at 1986 and the breakpoint at 1997. This was using the strucchange package in R. The 1977 breakpoint can be explained by a paper by McGuirk (Planetary-Scale Forcing of the January 1977 Weather, Science 199:4326 293-295 1978). The 1986 and 1997 breakpoints both coincide with El Nino events.

    My hypothesis is that each of these are cumulative adding one on the other. Much of the observed warming from 1977 through to now may be a result of this cumulative effect where the next event caused more heat to be added to the system before the heat from the previous event radiatively dissipated.

    Comment by Richard Steckis — 15 Jul 2009 @ 12:33 AM

  157. With regard to my analyses described above. I used the HadCRUt3 data from 1950 to present. This is the same period used the first graph.

    Comment by Richard Steckis — 15 Jul 2009 @ 12:52 AM

  158. raypierre (in reply to Hank Roberts, #141, 14 July 2009 at 12:38 PM ):

    But even if you had satellites in the right orbit, getting long-term instrumental stability to a level where you could detect the relatively small imbalances caused by ocean/atmosphere heat exchange would be difficult. Hansen and others argue that direct in situ monitoring of ocean heat storage, while also difficult, is less so.

    I can’t help but feel they are influenced by the fact that the same instruments needed for widespread direct in situ monitoring of ocean heat storage would also provide a great deal of information about ocean currents, the numerous ocean-driven climate modes (like ENSO), and in general a great deal of information against which test climate models.

    Comment by llewelly — 15 Jul 2009 @ 1:22 AM

  159. Raypierre, you wrote:

    “by this line of work is the extent to which some of the pause in warming mid-century might have been more due to decadal ocean variability rather than aerosols than is commonly thought”

    What is the present state of understanding of and ability to accurately model decadal ocean varability (which you suggest may have been the cause a “pause in warming mid-century”?

    Comment by Geckko — 15 Jul 2009 @ 3:23 AM

  160. So, Mr. Swanson, in short natural systems work in synergy and will in fact effectively reduce and pause warming; ocean/atmospheric dynamics convert energy continually, seems elementary to believe as you pointed out astutely that such digressions are reactions/responses in/on the system. General Chem and environmental science tells us this is so; this is a good review–educationaly post! People please re-read and the mod responses.

    [Response: This is not at all what the article says. The "pause," if it indeed exists, is temporary and has little if any effect on long-term climate sensitivity. You are just bringing your own preconceptions and misconceptions into it, and you don't seem to know either your General Chem or environmental science very well. Systems do tend toward a new equilibrium when conditions change, but the displacement of that equilibrium from the old one can be either amplified or damped by feedbacks. And sometimes, the equilibrium represents a transition to a new state altogether and in essence destroys the old state -- as in what happens when you pass the transition temperature for initiating combustion. There, that make you feel better? --raypierre]

    Comment by Jacob Mack — 15 Jul 2009 @ 6:26 AM

  161. #106 (raypiere) Absolutley! The thermohaline, and other oceanic dynamics are of utmost importance to consider. The Earth consists of a dynamic system, and in equilibrium it is dynamic and not static or 100%

    Comment by Jacob Mack — 15 Jul 2009 @ 6:29 AM

  162. I have decided to change my name from steve to stevec to help avoid any possible confusion over which are my posts. I have read comments that there is a lag time between surface temperatures such as measured by GISS and tropospheric temperatures such as measured by RSS and wondered if there was an established correlation and what might this time period be. thanks

    Comment by stevec — 15 Jul 2009 @ 7:04 AM

  163. The problem with current debate is that it focuses on global mean, annual temperatures (as dictated by climate models). You can put heat into a system, however, WITHOUT CHANGING THE TEMPERATURE. You can add heat to water at its boiling point with the temperature remaining the same (at 100C). As we all know, extra heat added changes the state of matter (liquid to gas). A green house gas molecule will absorb a photon of ir radiation without a detectable temperature increase – if the absorption line is sharp and discrete. The extra heat is used to change the molecule to a new vibrational state.

    Even excluding other factors therefore, like solar activity, it should be of no surprise that as we add more heat to the atmosphere, by increasing green house gas concentrations, annual mean global temperatures may not always increase accordingly. Other processes may be occurring that use up this extra heat – in ways that may even be unknown in such a complex system.

    Extra heat that accumulates in the atmosphere is redistributed in space (around the globe) and time (throughout the year and different seasons – when local conditions vary). I agree, therefore, with a view expressesd to me by Roger Pielke – that the focus should be on heat itself (and not temperature) and on spatial (local) and seasonal variability. The trends might then be more consistent and less open to doubt and criticism. It might also demonstrate that climate changes are already occurring on a local and seasonal basis.

    In a simple analysis of temperature records in a part of mid – Wales carried out in 2006, mean mid – winter and mid – summer temperature were seen to have increased by around 0.9 degrees Celsius over 60 years. Mean, spring time temperatures, however, had decreased slightly over the same period. The focus on mean annual global temperatures completely misses something like this – and this is far more meaningful and of significance to people living locally.

    Comment by Gareth John Evans — 15 Jul 2009 @ 8:27 AM

  164. The various “crystal ball” estimates of what is likely to happen to our climate once the current warming pause has ended are interesting.

    Rather than picking a trend starting in 1979 or 1950, maybe it would make more sense to take a longer-term look. After all, climate change is not something that can be measured using only short-term “blips” of a few decades in the record.

    If we take the entire Hadley record from 1850 to 2008, we see that the linear trend line is represented by the equation:
    y = 0.0041x – 0.4965

    This represents a long-term linear average warming rate of 0.041°C per decade.

    Continuing the long-term trend to year 2050, we arrive at a temperature anomaly of 0.328°C, which is quite close to the present 2008/09 value.

    So this would mean that the warming pause would continue until around year 2050, at which point warming would again follow the long-term trend line.

    At this continued warming rate we would have reached 0.536°C by year 2100, or slightly higher than the previous all-time record El Nino year of 1998.

    Comment by manacker — 15 Jul 2009 @ 8:31 AM

  165. Max Acker (manacker) draws a trend from 1850 forward in temperature and ends up at 2100 with no particular unpleasantness. But Max always assumes no effect of adding CO2 when telling us how the future is going to be cool.

    Comment by Hank Roberts — 15 Jul 2009 @ 9:12 AM

  166. Look him up. Why bother replying? Look what he posts about RC and climate:
    https://letters.salon.com/ace592d12ba8a39436beb337e351dcc4/author/index2.html

    Comment by Hank Roberts — 15 Jul 2009 @ 9:16 AM

  167. One man’s trend is another man’s cherry picking.
    Obviously the 1979 starting point for trend making is suspect.
    Especially since we are now seeing the presumed post 79 trend flatten when other than GISS data is included.

    Max makes a completely valid point and as good as any other specualtion with increased CO2 assumptions. CO2 has been soaring and temperature not. Any assumptions that increased CO2 is certain to trend temperature back on AGW track is no beter specualtion than Max’s.

    Comment by Howard S. — 15 Jul 2009 @ 9:41 AM

  168. “Any assumptions that increased CO2 is certain to trend temperature back on AGW track is no beter specualtion than Max’s.”

    Yes, why do we need radiative physics when we have thoughtless trend extrapolation?

    I did this with my weight. Currently, I’m gaining 5.5 pounds per year, so by the time I’m 80 I’ll weigh 440 pounds. No point in dieting now!

    Comment by Boris — 15 Jul 2009 @ 11:10 AM

  169. #163 John, there is something else which may actually mask a warming signal, despite not picking it up at times on the surface, I take yesterday as example and compare Density Weighted Temperatures from 3 significantly different locations. Forth Worth Texas scorching hot +38.8 C evening surface temp in its Upper air had a DWT to tropopause of 269.31 K. Cloudy Maniwaki’s +16 C chilly July weather gave a DWT 0f 262.93 (upper station near Montreal). Arctic Resolute Bay (central Canadian Archipelago) warmish +11 C gave a DWT of 261.73 K. Subtract surface temperatures from Fort Worth +38.8 C with Resolute +11 C and you get 27.8 K difference on the surface, yet for the entire Troposphere the difference is about 8 K. Thus it is hard to say from the surface record alone what is going on temperature wise, without considering the entire atmosphere.

    Comment by wayne davidson — 15 Jul 2009 @ 11:17 AM

  170. Hank Roberts 15 Jul 2009 at 9:16 am

    “Look [manacker] up. Why bother replying? Look what he posts about RC and climate:”

    Here’s a synopsis of what he’s written. Indeed, don’t fall for the “reasonable” brand of stripes manacker dons for his appearances on this site:

    http://www.realclimate.org/index.php/archives/2009/06/groundhog-day-2/#comment-129926

    Comment by Doug Bostrom — 15 Jul 2009 @ 11:29 AM

  171. Over at the open Mind blog, Mr. Galasyn posted a reference to Saltzman and Verbitsky, Paleooceanography, v9, 6, pp767-779, 1994. Briefly, he analyses the climate trajectory in the phase space of 3 variables, ocean temperature, ice mass, and CO2 concentration for the last 200KYr. We have longer and more data now, and I would welcome pointers to later work on the subject.

    Thanx
    sidd

    Comment by sidd — 15 Jul 2009 @ 11:40 AM

  172. The article says:

    “This overshoot is in the process of radiatively dissipating, and the climate will return to its earlier defined, greenhouse gas-forced warming signal.”

    If, as others have said, there is a committed warming (“heat in the pipeline”) of about half a degree, then why or how would the overshoot dissipate?

    [Response: The warming in the pipeline doesn't represent some pool of heat that is being gradually released into the atmosphere; it represents a radiative imbalance that is being gradually erased as the ocean warms up and comes into equilibrium. An event like a strong El Nino which temporarily pumps some extra heat from the ocean into the atmosphere (and thence to space) can cause a trend that exceeds the rate of gradual approach to equilibrium, whence the system will eventually have to relax back to the underlying trend. Another way of putting it is that a half degree of committed warming spread over, say, 20 years amounts to a trend of .025C per year (which doesn't count the continued increase of CO2). Anything that exceeds that rate can relax "back" despite the gradual weakening of the temporary ocean heat sink. --raypierre]

    Comment by Steve Milesworthy — 15 Jul 2009 @ 11:54 AM

  173. Actually, what I find interesting in the last month or two of data is the disconnect between very warm surface temps–as noted by Wayne–and the UAH lower trop anomaly–which is very much in the “average” range. Played around a bit on Woodfortrees to see if I could spot anything meaningful connected with this observation, and thought there might be some hint that this is something that can happen more often during PDO transitions. But that’s just eyeballing.

    Any insight on this out there? Or is this just a random fluctuation with no significance?

    Comment by Kevin McKinney — 15 Jul 2009 @ 1:19 PM

  174. Sidd, following up the phase space paper you asked about — I haven’t looked at these, but Google Scholar finds these mentions of it maybe worth checking:

    http://scholar.google.com/scholar?hl=en&q=Saltzman++Verbitsky+Paleoceanography+1994&btnG=Search

    Comment by Hank Roberts — 15 Jul 2009 @ 2:02 PM

  175. Hank Roberts (and Doug Bostrom)

    A tip: Try getting specific on the topic under discussion.

    It is more interesting than digging up old stuff that has little or nothing to do with the issue being discussed here.

    There is no doubt that warming will eventually resume. The question that the lead article has raised is whether the current warming interruption will last ten, twenty or forty years.

    It appears that the jury is out on this question, as I tried to point out.

    I would like to see some reasonable estimates on this, based not only on a relatively short-term myopic fixation on AGW greenhouse gases, but including all the many other factors that influence our climate long-term, as Dr. RayPierre has also pointed out.

    Following the long-term trend line is, indeed, a speculation, as Howard S. has written, but, in the absence of another more credible speculation, it remains a viable guess on what is really going to happen longer term.

    Bring us a better speculation, along with supporting evidence (not just model outputs), if you can.

    Max

    Comment by manacker — 15 Jul 2009 @ 2:06 PM

  176. #173, Kevin, I lament not seeing DWT maps readily available on the internet. But, from what I gather, the Arctic is as warm as it gets right now. Despite an impressive consistent cloud cover, so now is the time when the ice will disappear very fast. As far MU upper air averages, I think they lack verification, I suspect that they are having problems with accuracy. The data seems unclear, what altitude for comparison sakes (I suspect its roughly defined)? So I take this data with a grain of salt. The Fort Worth tropopause was extremely cold compared to Resolute Bay high up in the Arctic. If MU mixes high troposphere data with mid troposphere, in the case of Fort Worth then it would inject the cold Upper Air (as prescribed by models when there is a very hot surface), conversely so for Resolute Bay’s warm atmosphere. DWT’s from Upper Air balloon profiles demolish all these problems, and give data well within where Greenhouse gases do their thing.

    Comment by wayne davidson — 15 Jul 2009 @ 2:32 PM

  177. manacker 15 Jul 2009 at 2:06 pm

    “A tip: Try getting specific on the topic under discussion. ”

    In your own words:

    “Real Climate is selling AGW hysteria.”

    “As such, it [the IPCC report] is full of agenda driven pseudo-scientific exaggerations and distortions, which all go in the direction of making its ‘pitch’.”

    “The belief that ‘scientists know best’ is flawed (after all, ‘climatology’ is still in its infancy as a ‘science’ and many of the so-called climate “scientists” are in fact only computer jockeys.”

    I congratulate you for allowing us to follow your rhetoric over time and space, very few others do that. That being said, you can’t escape the history you’ve created. You give the appearance not only of being prone to emitting inflammatory nonspecific rhetoric, but also that of a hypocrite.

    Or is there another Max Anacker?

    “Bring us a better speculation…”

    Who’s “us”, Kimo Sabe?

    Comment by Doug Bostrom — 15 Jul 2009 @ 2:51 PM

  178. I don’t know about interrupted warming, but the latest SST data shows a big jump in the last couple months, to levels not seen since 1998; GISS also has June as the second warmest on record (LOTI). That seems pretty significant in light of the still relatively low Nino 3.4 anomalies, suggesting that an even larger increase is likely, though some of it could also be rebound from the recent La Nina (seems too large though and coincides more with the development of El Nino conditions, then again I always hear that anomalies lag ENSO by 3-6 months).

    Comment by Michael Stefan — 15 Jul 2009 @ 3:23 PM

  179. > … short-term myopic fixation on AGW greenhouse gases, but
    > including all the many other factors that influence our climate
    > long-term, as Dr. RayPierre has also pointed out

    This sort of thing is so loaded with misstatements that response goes nowhere but generates more attention for Max for a while.

    You can’t be myopic — nearsighted — to focus on the CO2 forcing.
    It’s the big one on the left.

    You have to stand back and be a bit farsighted, to compare them.
    Then, lean in close to see the little ones:

    http://www.globalwarmingart.com/images/0/07/IPCC_Radiative_Forcings.gif

    Comment by Hank Roberts — 15 Jul 2009 @ 4:09 PM

  180. #172 Yes I understand that committed warming relates to a radiative imbalance. But if the El Niño somehow caused a temporary acceleration in the warming, wouldn’t this merely overcome part of the imbalance meaning that warming ought to continue. Perhaps I’m being overly fussy about a throwaway line, but I guess it seems more likely that the current “cooling” is just another expression of the variability.

    Comment by Steve Milesworthy — 15 Jul 2009 @ 5:20 PM

  181. 178 I disagree with the technique of leaving out 1998-2008 when determining the trend. It assumes that the atmosphere and top couple feet of surface can hold enough heat to warm the planet above the background for 20-25 years regardless of negative ENSOs.

    I agree that it places a lower bound on the situation, but it isn’t the median expected value. It’s a dangerous position to take, betting on the lower bound. I can be convinced, but so far the hypothesis seems weak.

    Comment by RichardC — 15 Jul 2009 @ 5:36 PM

  182. Raypiere responded at 172:

    “An event like a strong El Nino which temporarily pumps some extra heat from the ocean into the atmosphere (and thence to space) can cause a trend that exceeds the rate of gradual approach to equilibrium, whence the system will eventually have to relax back to the underlying trend”

    Would you elaborate? The idea that there are elasticities in the climate system makes sense, I just don’t know where to start learning.

    Comment by Mike#22 — 15 Jul 2009 @ 5:58 PM

  183. All,
    Here is a mark-up of , Hadcrut annual global average temperatures to 2008 in which there is an arguably similar “pause” in warming, and other features centred around 1940.

    Back in 2003, Klyashtorin & Lyubushin demonstrated that there appears to be a superimposed cycle of around 62 years over the underlying trend. Others have put it at around 60 years:
    The underlying cause is unknown, just as with various ocean oscillations.
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    Doug Bostrom & Hank Roberts; can you see something of potential to ridicule in the name ’Lyubushin’?
    Have fun!….. no need to confuse us with any scientific comments.

    Comment by BobFJ — 15 Jul 2009 @ 6:31 PM

  184. manacker 15 Jul 2009 at 2:06 pm

    “A tip: Try getting specific on the topic under discussion. ”

    Speaking of which, elsewhere you’ve asked a rhetorical question:

    “But why do so many scientists and political leaders plus many in the media support the man-made global warming theory?”

    You answered yourself and whatever credulous bystanders (at an Accuweather blog) were in earshot with these assertions:

    ‘It’s driven by an estimated 2.5 to 4 billion dollars per year in climate research grants, with the grants going selectively to those scientists who make the most disastrous predictions.’

    and

    ‘The politicians and bureaucrats love the idea of “carbon taxes”, higher taxes on fossil fuels, “carbon footprint offset” schemes, etc., because it gives them more money to spread around (and more power).’

    As we’re putatively discussing science and facts here, and in your currently displayed persona you’ve requested that we stick to specifics, are you able to cite some reasonably trustworthy (ie, peer-reviewed or non-partisan governmental) sources for those remarkable claims?

    Comment by Doug Bostrom — 15 Jul 2009 @ 6:45 PM

  185. 180 Steve asks, ” if the El Niño somehow caused a temporary acceleration in the warming, wouldn’t this merely overcome part of the imbalance meaning that warming ought to continue.”

    Not quite. The underlying hypothesis is that the air temp gets ahead of ocean heat content, so air temp pauses as it waits for the oceans to catch up. I can see that for a year or so, but the time scales for Warming, Interrupted seem too long. I’d think the next negative ENSO would get us back to the underlying trend.

    NOTE TO MODERATORS: This lack of captcha is GREAT! If it doesn’t attract spam, it would be nice if it could stay this way.

    Comment by RichardC — 15 Jul 2009 @ 6:53 PM

  186. I just don’t know where to start learning.

    The fluctuation dissipation theorem :

    http://en.wikipedia.org/wiki/Fluctuation_dissipation_theorem

    http://www.math.sdsu.edu/AMS_SIAM08Shen/Abramov.pdf

    http://meetingorganizer.copernicus.org/EGU2009/EGU2009-10894.pdf

    Not much out there yet.

    Comment by Thomas Lee Elifritz — 15 Jul 2009 @ 8:27 PM

  187. “Point is, when the temperatures are not doing “what they are meant to do” it is hard to deal with sceptics who suggest that within climate variability there is a hidden downward trend.”
    “Following the long-term trend line is, indeed, a speculation, as Howard S. has written, but, in the absence of another more credible speculation, it remains a viable guess on what is really going to happen longer term.”
    Despite the apparent pause in the atmospheric temperature trend, there is a very NOT hidden downward trend in ice; arctic summer ice cover, glacier mass, increasing Greenland yearly ice melt, and a march of disintegrating ice shelves further south around Antarctica. The denialosphere saying “the warming has stopped” in the face of accelerating ice melt is insane, especially after all the flack they’ve put out about how GISS, HadCRUT & so on are not reliable or accurate. Maybe the UHI effect is decreasing as the average SEER of air conditioning increases; anybody want to bet there’s a correlation? &;>)
    My viable guess, looking at the trends in ice, and absent any credible explanation (I don’t think GCRs, or clouds, are melting the ice) is that seashore property isn’t a good longterm investment.

    Comment by Brian Dodge — 15 Jul 2009 @ 9:44 PM

  188. BobFJ 15 Jul 2009 at 6:31 pm

    “Doug Bostrom & Hank Roberts; can you see something of potential to ridicule in the name ’Lyubushin’?”

    Can’t speak for Hank Roberts, but for myself I’ll say that if Lyubushin has not made any asinine comments such as this direct quote from “manacker” you won’t hear a thing from me:

    “Use your common sense. It’s all a hoax.”

    Kind of like the Apollo landings. “It’s all a hoax.” Sure, Max, whatever…

    Comment by Doug Bostrom — 15 Jul 2009 @ 11:50 PM

  189. #63 Greg states

    But the author’s math is not grounded in a single physical principal. It is an analysis of a single dependent variable at an intermediate level of the total system and is not isolated from influences from the other components. The entire set of results could just be artifacts of other, un-named, processes.

    I fail to see what predictive value there is in this approach.

    There is little, if any, predictive value in this approach, but there is a lot of *proscriptive* value (GHG’s should be proscribed lower)

    This contrasts with highly valuable 3 to 10 day ahead weather predictions, and ENSO forecasts, both of which have highly tangible values.

    Things like how many years before my house gets inundated etc. is still an intangible risk, even if one knows the risk is increasing gradually.

    All long term climate predictions can just tell you that you should reduce ghg’s, not how best to deal with the consequences.

    Comment by Marco Parigi — 16 Jul 2009 @ 12:52 AM

  190. raypierre

    I have a problem with your response 172.
    You say that an El Niño pump heat from ocean towards space.
    In this case the unbalance should be negative (increasing of flux towards space).
    But, in this link :http://earthobservatory.nasa.gov/Features/OceanCooling/page2.php I see, on the contrary, an positive net TOA flux.
    There is, as it is normal in this case, a correlation with the increasing ocean heating.
    Can you explain me?

    Comment by pascal — 16 Jul 2009 @ 1:50 AM

  191. Alex Harvey 109, wrote in part:

    “… In the little ice age, as I understand it, temperatures fell gradually over a number of centuries to correspond in some as yet unexplained way with the “Maunder Minimum,” a period of reduced sunspot activity. It seems fairly reasonable to suppose that had humans emitted no CO2 at all, temperatures would have risen again anyway in the same pattern that they had fallen previously, i.e. gradually and over a number of centuries…

    I would like to add that there is a big long-term experiment ongoing at CERN, that is checking out some initial work by Svensmark, indicating that the climate effects resulting from the sun’s activity are far more complicated than just the simple emission intensity of sunlight. For instance, the low sunspot activity during the “Maunder Minimum”, as mentioned by Alex may well have complex effects other than the purely thermal from sunlight.
    And then of course, there has been a long and remarkable dearth of sunspots of late, and debate as to when the next solar cycle will start. There was stir of excitement in some quarters a couple of weeks ago, when a pair of modest sunspots were noticed. However, the SOHO MDI real-time image seems to have returned to the long-time norm of zero sunspots. Check it out for yourself at:
    http://sohowww.nascom.nasa.gov/data/realtime/mdi_igr/512/
    But then, if there are no sunspots, and if you are concerned about global warming, then clearly, it is GOOD NEWS of indication of at least more delayed warming. (not to mention less interference in communications ETC)
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    BTW, a quickie to; Kevin McKinney, Hank Roberts, and Patrick 027;
    Please look carefully at the high quality image from SOHO MDI, and compare it with human capability on the ground in protected looking for limb darkening of the sun. Oh and BTW, compare also with the Wiki’ article and its poor quality exaggerated image. Oh and BTW Wiki’ does not mention a second and possibly more important reason for this trivial nit picking consideration.

    Comment by BobFJ — 16 Jul 2009 @ 2:31 AM

  192. It’s just 1 month…but el nino condition are at the begin and NCDC ocean anomaly for june is already the highest of the time series:
    ftp://ftp.ncdc.noaa.gov/pub/data/anomalies/monthly.ocean.90S.90N.df_1901-2000mean.dat

    Comment by gp2 — 16 Jul 2009 @ 2:57 AM

  193. Something of a perfect storm is developing in the denial world, as can be seen from comments here http://www.skepticalscience.com/Climate-time-lag.html and here http://www.huffingtonpost.com/david-horton/like-a-diamond-in-the-sky_b_234611.html and from post and comments here http://www.abc.net.au/unleashed/stories/s2626711.htm. The elements are Plimer’s book, some wacky theories on cosmic rays and clouds and time lags issuing from denial central, and an absolute renewed refusal to recognise any changes in ice cover, ecology, ocean chemistry etc, and indeed a refusal to recognise even the greenhouse effect itself. And sucked into the vortex, dear Real Climatians, is this very post “Warming, interrupted: Much ado about natural variability”, seen as RC’s endorsement of a downward turn in temp rise, and final proof that CO2 is irrelevant to the world and just a plot by Gore and Soros to rule us all. It is all reminiscent, is it not, of rolling the boulder up the hill over and over while crows peck out your entrails, or whatever that marvelous mythological model is.

    Comment by David Horton — 16 Jul 2009 @ 3:35 AM

  194. Oh one minor correction: I should have said inter-decadal climate variability and associated climate shifts.

    Comment by Jacob Mack — 16 Jul 2009 @ 5:05 AM

  195. Is there any physical evidence of this alleged overshooting?

    On what basis do you claim that warming will resume in 20 years?

    This resumption could be expected if you believe that PDO/AMO cycles are driving temperature much more than increased GHG, but is that not contrary to AGW orthodoxy?

    Comment by Allan M R MacRae — 16 Jul 2009 @ 5:24 AM

  196. Interesting read. But seems like a real problem for prospects of geo-engineering – if there are such non-linear (or unpredictable) effects from ocean etc then controlling geo-engineering interventions is going to be difficult. …

    Comment by William T — 16 Jul 2009 @ 5:40 AM

  197. Hank Roberts #165 “Max Acker (manacker) draws a trend from 1850 forward in temperature and ends up at 2100 with no particular unpleasantness. But Max always assumes no effect of adding CO2 when telling us how the future is going to be cool.”

    But manacker’s trend is (so far) empirically observed. He assumes nothing. He merely extrapolates this (linear) trend. Any CO2 increase is already included as a contributor to the observed temperature trend since the Industrial Revolution.

    Now a reasonable person might think this a point worth making.

    And yet you immediately follow this post by saying (#166) “Look [manacker] up. Why bother replying? Look what he posts about RC and climate” so enjoining us to ignore manacker on account of his political views.

    Comment by simon abingdon — 16 Jul 2009 @ 5:56 AM

  198. When we think of 2 degrees we kinda forget the issue of the burst of GHG emissions that, after a lag of a few hundred years, followed the up-kick in temperature in past deglaciations. Estimates of The Lag range from about 800 years to much less – maybe as short as 200 years.

    For longer lags (C800 years) the source of CO2 is sometimes suggested as being the CO2-laden waters of the deep ocean, 800 years being about the over-turning time for the ocean.

    I haven’t been able to find any clear source for the volume of CO2 and CH4 that would give rise to the observed changes for shorter lags, but that it happened is undeniable.

    As far as I can find the rate of temperature rise over these warming periods is maybe one degree K per thousand years – i.e. an average of about 0.1 degrees per century. Thus the likely temperature change to trigger the release of CO2 and CH4 is of the order of 0.2 to 0.8 degrees K.

    We have already measured 0.6 degrees warming attributable to man over the last century, so it seems we are well into the band of temperature rise that triggered the GHG release at the end of The Lag in the past. So just how close to disaster are we?

    Comment by Nigel Williams — 16 Jul 2009 @ 6:08 AM

  199. simon abingdon:

    He assumes nothing. He merely extrapolates this (linear) trend.

    I love the smell of self-contradiction in the morning …

    Comment by dhogaza — 16 Jul 2009 @ 7:08 AM

  200. Hank Roberts #165 “Max Acker (manacker) draws a trend from 1850 forward in temperature and ends up at 2100 with no particular unpleasantness. But Max always assumes no effect of adding CO2 when telling us how the future is going to be cool.”

    But manacker’s trend is (so far) empirically observed. He assumes nothing. He merely extrapolates this (linear) trend. Any CO2 increase is already included as a contributor to the observed temperature trend since the Industrial Revolution.

    Now a reasonable person might think this a point worth making.

    I think I’m a reasonable person, and my understanding is that a higher concentration of atmospheric CO2 means a higher *rate* of warming – a steeper trend – and that since atmospheric CO2 is steadily increasing, we should expect to see the slope of the warming trend steadily increasing too.

    [Response: No, this has been covered here before. The radiative forcing by CO2 is roughly logarithmic. That means that an exponential increase in CO2 leads to a roughly linear (i.e. constant) warming trend. Of course, this is somewhat irrelevant anyway, since the existence of other significant anthropogenic forcings such as the other greenhouse gases, sulphate aerosols, land use change, etc. leads to a far more complicated time history of anthropogenic forcing. There is also a substantial contribution from internal variability which adds considerable 'noise' to the record. That means that it is extremely difficult if not impossible to isolate the the response of the climate to CO2 increases alone in the observed trends. If that were possible, we'd have a tight constraint on climate sensitivity from the observational record alone. But we don't. We need to turn to other sources of information, e.g. the observed paleoclimate response to past changes, to place better constraints on the 'climate sensitivity'. -mike]

    Comment by Icarus — 16 Jul 2009 @ 7:19 AM

  201. “But manacker’s trend is (so far) empirically observed.

    Comment by simon abingdon ”

    And max decries the IPCC reports and climate models as merely curve fitting.

    Where is his science?

    “He assumes nothing.”

    Yup, he certainly does THAT all right.

    And he isn’t extrapolating a trend. He’s drawing a line between two points and continuing the line. He’s not even fitting all the data, he’s fitting two points of the data.

    Comment by Mark — 16 Jul 2009 @ 7:50 AM

  202. “On what basis do you claim that warming will resume in 20 years?”

    Because the underlying forces have not changed.

    Duh.

    There was a man who fell from a high storey building. His descent was halted by an updraft and he was thrown through a window and survived. (he may have jumped, can’t remember).

    Yet if that window hadn’t been there, even though his descent was halted by an updraft, he would have resumed his plummet groundward.

    Why?

    Because gravity still exists.

    Comment by Mark — 16 Jul 2009 @ 7:52 AM

  203. “and an absolute renewed refusal to recognise any changes in ice cover, ecology, ocean chemistry etc”

    Although their faith in these proxies are astounding when they can be stated to “disprove” AGW…

    Comment by Mark — 16 Jul 2009 @ 7:53 AM

  204. http://www.sciencedaily.com/releases/2009/07/090714124956.htm

    PETM (55 million years ago) is for some reason being related to todays climate change (CO2 emissions I am presuming) only it happened over 10,000 years then (relatively quick in geological terms I am presuming) with CO2 emission 70% then pre industrial cannot explain the entire warming which seems to be major news on this peer reviewed paper.

    Antatrica was not iced over during this time and other conditions may have been very different to today so it not being CO2 but something else seems to be giving the deniers ammunition against the GCM which seems silly and daft. James Hansen has already alluded to earth sensitivity being double originally thought but these scenarios are omitted from the IPCC 2007 FAR due to nt ebough being known about longer time feedbacks which may make up the difference and only paint a blacker picture for us?

    Comment by pete best — 16 Jul 2009 @ 7:59 AM

  205. dhogaza (#199) and Mark (#203) Well, Mauna Loa CO2 increase looks linear to me, so we can extrapolate that pretty confidently. The rest: clouds, oceans, albedo etc is all noisy, so we’ll have to wait 30 years to see whether there really is cooling now or that the observed gentle warming trend has continued.

    Comment by simon abingdon — 16 Jul 2009 @ 8:30 AM

  206. Most of this won’t be news to regulars, but re the “pause” in warming, here’s what I wrote elsewhere this morning on the topic of “cooling since 1998″:

    As to the “it’s been cooling since 1998″ hooha repeated several time on this thread, here is the list of the ten warmest years in the instrumental record (STR ’05 dataset) from warmest to coolest:

    2005
    1998
    2002
    2003
    2006
    2007
    2004
    2001
    2008
    1997

    Oh, and it’s a virtual certainty that this year will come in significantly warmer than last, which will mean that there will be no years prior to 1998 in the top ten list, since ’97 will be bumped to 11th. . .

    But perhaps you don’t trust surface thermometers? Well, how about the UAH satellite data, beloved by denialists because it always shows the lowest warming trend of any common metric? A while back I downloaded their data and averaged ’89-’98 and ’99-’08 separately:

    90s: .04367 C above baseline temp
    00s: .20025 C above baseline temp

    So the decadal average for the 00s was .15 C warmer than the 90′s. As I said earlier, love that “cooling”. . .

    Check my work if you like:

    http://vortex.nsstc.uah.edu/public/msu/t2lt/uahncdc.lt

    Comment by Kevin McKinney — 16 Jul 2009 @ 8:49 AM

  207. “PETM (55 million years ago) is for some reason being related to todays climate change (CO2 emissions I am presuming) ”

    The reason why it is being used is because it counters the “proof” against AGW of the 800 year lag.

    That “proof” is only true if CO2 is never the cause, only the result of warming.

    PETM shows that CO2 can precede warming, removing even the vaguest appearance of validity (which the argument of the cores never had anyway, since the heating AFTER CO2 would be caused BY that CO2 and therefore, unless you have a tachyonic CO2 molecule, would cause warming AFTER its increase).

    But when dealing with the morbidly credulous, you need to knock down even the vaguest appearance of relevance if that relevance doesn’t in reality exist.

    Comment by Mark — 16 Jul 2009 @ 8:54 AM

  208. “and that since atmospheric CO2 is steadily increasing, we should expect to see the slope of the warming trend steadily increasing too.”

    No more than the knowledge that gravity is a constant on the earth should mean that a feather will fall steadily if dropped…

    Comment by Mark — 16 Jul 2009 @ 8:56 AM

  209. pete, a high long term climate sensitivity would indicate that some significant portion of the warming of the last half of the 20th century would be from the long term climate sensitivity of the first half of the 20th century.

    Comment by stevec — 16 Jul 2009 @ 8:57 AM

  210. BobFJ, first look up the paper.
    Are you talking about this one?

    Klyashtorin L.B.1; Lyubushin A.A.2
    Energy & Environment
    Volume 14, Number 6, 1 November 2003 , pp. 773-782(10)

    Look it up; look for citing papers. Has anyone published anything relying on it?

    Comment by Hank Roberts — 16 Jul 2009 @ 9:42 AM

  211. “dhogaza (#199) and Mark (#203) Well, Mauna Loa CO2 increase looks linear to me, so we can extrapolate that pretty confidently. The rest: clouds, oceans, albedo etc is all noisy, so we’ll have to wait 30 years to see whether there really is cooling now or that the observed gentle warming trend has continued.

    Comment by simon abingdon”

    Why are you assuming that the only effect on temperature is CO2?

    Are YOU the one all the denialists are complaining about when they say that AGW is all about CO2 and ignoring anything else?

    Comment by Mark — 16 Jul 2009 @ 9:57 AM

  212. So far no one has wagered a (scientifically based and possibly even climate model supported) guess on when the current warming interruption will stop and warming will resume.

    My guess was simply based on the long-term trend line.

    The recorded fact is that the period 1910-1944 saw a linear warming of 0.53C (Hadley), 1944-1975 saw a very slight cooling and 1976-2000 (or 2005) saw warming of 0.37C (or 0.43C) (also Hadley). The warming has been interrupted, although the current years are still among the warmest recorded, as has been noted above.

    Prior to that, the short period right after modern measurements started showed a cooling trend (1850-1857). This was followed by a warming period from 1858 to around 1879, which was followed by a cooling trend from 1880-1909.

    And over the entire period with all the multi-decadal warming/cooling cycles there was an underlying warming trend of 0.041C per decade.

    Theories have been presented explaining these multi-decadal warming/cooling cycles with natural variation factors, and the long-term trend has been explained by a combination of natural and anthropogenic factors.

    The 19th century warming and cooling trends have not gotten much attention, as it is unlikely that human emissions played a major role here.

    The 1910-1944 warming trend has been studied, with the conclusion that the climate models were not able to fully explain this warming period.

    The 1944-1975 slight cooling period has been suggested to have been caused by human aerosol emissions that masked the warming from the rapidly increasing human CO2 emissions in the post-war boom years. Very little if any empirical data have been presented to support this rationalization, as far as I have seen, but maybe someone out there has seen something specific along these lines.

    The 1976-2000 (or 2005) period of rapid warming and increased atmospheric CO2 concentrations has gotten most of the attention. This is the period most often cited by IPCC.

    The question raised by stevec (209) is whether or not “some significant portion of the warming of the last half of the 20th century would be from the long term climate sensitivity of the first half of the 20th century” (i.e. early 20th century warming “still in the pipeline” until the late 20th century).

    An even more pertinent question now is:

    When is the warming going to resume, and, when it does, will it follow the long-term trend line or will it follow a new accelerated trend line driven by anthropogenic GHG emissions (primarily CO2) as estimated by the climate models cited by IPCC?

    Max

    Comment by manacker — 16 Jul 2009 @ 10:34 AM

  213. Mike (response #200):

    The radiative forcing by CO2 is roughly logarithmic. That means that an exponential increase in CO2 leads to a roughly linear (i.e. constant) warming trend.

    Actually Mike, an exponential increase in the CO2 anomaly over pre-industrial (as we are seeing approximately) will lead to an accelerated forcing. Only when getting to 2x CO2 and beyond, will it gradually level off to linear.
    But in the regime discussed this is not yet relevant.

    [Response: True, I should have been more precise here. The typical approximate formula for the radiative forcing is F=-6.3 log (C/C0) where C is the actual Co2 concentration, and C0 is the value (roughly 300 ppm) at the turn of the 20th century. This represents the equilibrium warming, not the transient (observed) warming, which is an important distinction since the warming is not in equilibrium with the forcing on the timescales of decades of interest here. But this notwithstanding, lets consider the equilibrium warming (the warming that would eventually be realized in response to a given increase in CO2 concentrations). Due to the log dependence, the associated increase in radiative forcing (and consequently the ultimate realized warming) goes as the percent increase in CO2. Going from, say, 1968 to 2008 (a 40 year period), the increase in CO2 has been from roughly 322 ppm to 386 ppm, an increase of about 20%. If we continue on the so-called 'business as usual' trajectory, we will reach roughly double pre-industrial (280ppm) levels, i.e. somewhere in the range of 550 ppm, over the next 40 years. That represents an increase of roughly 42%, implying nearly twice as much co2-related warming for the increase in CO2 over the next 40 years as for the increase of the past 40 years (though in reality, this is very much complicated by the precise role that sulphate aerosols have played in the past, and will play in the future). On the other hand, if we were to slow the increase in such as way that we hold CO2 levels to 450 ppm by mid-century, then the % increase over the next 40 years would be 16.5%, and there would be slightly less ultimately realized warming than for the previous 40 year, i.e. the rate of warming would actually slow. Note however that the absolute change in CO2 concentrations in this scenario would be identical for both 40 year intervals! (64 ppm), demonstrating that the process is indeed not linear with increase in CO2, i.e. the logarithmic dependence really *does* matter here. -mike]

    Comment by Martin Vermeer — 16 Jul 2009 @ 10:37 AM

  214. Sidd, in 2001, Saltzman published a book that expands on the idea significantly:

    Dynamical Paleoclimatology: Generalized Theory of Global Climate Change

    Great stuff!

    Comment by Jim Galasyn — 16 Jul 2009 @ 11:34 AM

  215. Doug Bostrom

    The topic here is the apparent interruption in global warming, when it will likely end and at what rate the warming is likely to resume, not “moon landings”. Get it?

    Max

    Comment by manacker — 16 Jul 2009 @ 11:52 AM

  216. Kevin McKinney

    Your analysis (206) of UAH temperature anomalies of the 90s vs. the 00s is interesting, and is no doubt correct.

    Another way of looking at it is the method preferred by IPCC: determine a linear trend line over the period measured.

    Doing it this way shows a linear cooling rate of around 0.1°C per decade on average over the 4 main records: (Hadley, GISS, UAH, RSS) from January 2001 to today (the 21st century, so far).

    How long this trend will continue is anyone’s guess, as is the warming rate that will ensue when the current warming interruption has ended.

    I believe that is in essence what we are all discussing here, starting with the lead article by Kyle Swanson.

    Max

    Comment by manacker — 16 Jul 2009 @ 12:07 PM

  217. re #205

    dhogaza (#199) and Mark (#203) Well, Mauna Loa CO2 increase looks linear to me, so we can extrapolate that pretty confidently. The rest: clouds, oceans, albedo etc is all noisy, so we’ll have to wait 30 years to see whether there really is cooling now or that the observed gentle warming trend has continued.

    simon, “looks” ain’t the same as “is”! For example the average yearly increase in atmospheric CO2 concentrations during the decade 1990-1999 was around 1.59 ppm/yr (see Mauna Loa site urled below). During the 2000-2009 “nearly” decade, the average yearly increase in atmospheric CO2 is around 1.98 ppm/yr.

    http://www.esrl.noaa.gov/gmd/ccgg/trends/

    So the increase in atmospheric CO2 isn’t linear whatever it may look like. It’s got a greater than linear increase. It’s likely that the greater than linear increase in atmospheric CO2 will continue for some time, since (a) there is no evidience that emissions will stop increasing during the foreseeable future, and (b) it becomes progressively more “difficult” for the oceans to absorb increasing amounts of CO2 as the surface layers tend towards saturation.

    So extrapolation based on a false presumption of linearity is dubious….

    Comment by chris — 16 Jul 2009 @ 12:31 PM

  218. Sorry, Max, you’re doing the same thing again, ignoring the basics to make a statement that appears sensible.

    How long do you need to collect temperature data to say with statistical confidence that there is either an up or down trend, given the variability we know about?

    Comment by Hank Roberts — 16 Jul 2009 @ 12:37 PM

  219. Well, my analysis–a somewhat pretentious word for a simple operation, I fear–was motivated by the fact that trend lines are very often abused by cherry-picking start and end dates.

    So comparing entire decades clarifies what the alleged “cooling” might mean for those (like me!) who are not particularly sophisticated in math/stats. Or so I hope, at least.

    With all due respect, I would say that the “trend since 2001″ is statistically meaningless.

    Comment by Kevin McKinney — 16 Jul 2009 @ 12:56 PM

  220. Mike, I have to study it more but I found your explanation (213) of relative forcing helpful. One odd question: when did the log coefficient become 6.3 and what is the significance/meaning of the minus sign?

    [Response: Oops, not sure how those typos got in. The approximate formula for the forcing should be F=5.35 log (C/C0) and there is of course no negative sign! -mike]

    Thanks, Martin for opening the door.

    Comment by Rod B — 16 Jul 2009 @ 12:59 PM

  221. Re #191

    I would like to add that there is a big long-term experiment ongoing at CERN, that is checking out some initial work by Svensmark, indicating that the climate effects resulting from the sun’s activity are far more complicated than just the simple emission intensity of sunlight. For instance, the low sunspot activity during the “Maunder Minimum”, as mentioned by Alex may well have complex effects other than the purely thermal from sunlight.

    BobFJ, it’s not really a big experiment! The experiment involves filling a chamber with an atmosphere mix containing trace O3 and sulpher dioxide, using UV to convert sulpher dioxide into sulphuric acid and using a gamma ray source to induce nucleation particles that are detected with a particle detector.

    The “initial work” was an observation of a correlation between the solar cycle and low cloud cover (LCC) during solar cycle 22 using the ISCCP-IR product. This correlation starts to fail around the mid-1990′s and there isn’t really a correlation through cycle 23 to present. If the more reliable ISCCP-IR/vis product is used the correlation is poorer still. The idea, anyhow, is that the gamma rays (cosmic ray flux or CRF) result in atmospheric ionization which promotes cloud condensation nuclei (CCN) which nucleate low level clouds which “cool” the earth’s surface. Reduced CRF results in reduced nucleation of LCC with a warming forcing.

    Simples! However, while Svensmark has puffed this initial observation/hypothesis, writing a (dismal IMHO) book and publicising like mad with press releases and such like, it’s been left to a few other groups to address the empirical evidence for such a link (i.e. causal CRF – LCC link). This has been done in detail by two groups (see references below) who have independently come to the same conclusion – there isn’t a detectable causal relationship between the CRF and LCC, and any apparent correlation that might be occasionally apparent with the solar cycle is with the irradiance component of the solar cycle (rather than the CRF which varies in roughly (anti)-phase with the solar irradiance).

    That’s not to say that the solar – climate effects aren’t complex. However there isn’t really much evidence for the Svensmark hypothesis at all, although you wouldn’t know it from the relentless self-publicising from some quarters!

    Kristjánsson, J. E., A. Staple, J. Kristiansen, and E. Kaas, A new look at possible connections between solar activity, clouds and climate, Geophys. Res. Lett., 29(23), 2107, 10.1029/2002GL015646, 2002.

    Kristjansson JE, Kristiansen J, Kaas E (2004)
    Solar activity, cosmic rays, clouds and climate – an update
    Adv. Space Res. 34, 407-415.

    Kristjansson JE, Stjern CW, Stordal F, et al. (2008) Cosmic rays, cloud condensation nuclei and clouds – a reassessment using MODIS data Atmos. Chem. Phys. 8, 7373-7387.

    Sloan T, Wolfendale AW (2008) Testing the proposed causal link between cosmic rays and cloud cover Environ. Res. Lett. 3 art. # 024001

    A.D. Erlykin, T. Sloan, A.W. Wolfendale (2009) The search for cosmic ray effects on clouds J. Atmos. Solar Terrestr. Phys. 71, 955-958

    A.D. Erlykin, G. Gyalai, K. Kudela, T. Sloan, A.W. Wolfendale (2009) Some aspects of ionization and the cloud cover, cosmic ray correlation problem J. Atmos. Solar Terrestr. Phys. 71, 823-829

    Comment by chris — 16 Jul 2009 @ 1:03 PM

  222. Actually Max when I hear the term “heat in the pipeline” I think of the short term climate sensitivity as affected by the lag from having to warm up the oceans while when I use the term long term climate sensitivity I think of such things as melting ice, trees growing further north, and the release of methane. Perhaps I have my terminology wrong but in my mind I seperate the issues in this manner and my comment was based on this understanding.

    Comment by stevec — 16 Jul 2009 @ 1:58 PM

  223. NCDC data for June is out. GISS already told us it was the second-warmest ever. NCDC has the same ranking; what’s striking is that this is the warmest ever June for oceanic temps and also for SH temps.

    Say hello to El Nino. . . or “buenas dias,” if you prefer.

    Comment by Kevin McKinney — 16 Jul 2009 @ 3:10 PM

  224. One of the problems with the radiative forcing model is that it applies to either differences in solar forcing or differences in GHG forcing. For example, the difference in the incident radiation from the Sun is about 80 W/m^2 between perihelion (Jan) and aphelion (Jun). At 20 W//^2 average

    Comment by co2isnotevil — 16 Jul 2009 @ 3:38 PM

  225. #224, Kevin, The big piece of info from NCDC: ocean temps were warmest ever, beating 2005. My case is closed, Hadley Centre needs a revision of methods, there is no “pause”. Either from the sea, nor above land. Note: Present El-Nino had a weaker start than 1997 yet the GT is much warmer than June of 1997. Combined with my own measurements by other refraction means, I am totally convinced that the warming continues despite strong La-Nina episodes.

    In addition; Data from radiosondes, RATPAC were much warmer than MU UAH upper air measurements, telling indeed…

    Comment by Wayne Davidson — 16 Jul 2009 @ 4:13 PM

  226. Chris (#217) Lucky then that CO2 needs to be logarithmically increasing to have a linear effect on temperature.

    Comment by simon abingdon — 16 Jul 2009 @ 4:36 PM

  227. Mark (#211) “Why are you assuming that the only effect on temperature is CO2?” I’m not. (But the President of the United States seems to think it’s important).

    Comment by simon abingdon — 16 Jul 2009 @ 4:42 PM

  228. manacker 16 Jul 2009 at 11:52 am

    “The topic here is the apparent interruption in global warming, when it will likely end and at what rate the warming is likely to resume, not “moon landings”. Get it?”

    I appreciate or “get” that you’re naturally quite keen to maintain the persona you adopt when visiting sites such as this one, where your audience is reasonably well informed. Losing the hermetic nature of this persona and having attention called to your other manifestations will degrade your local credibility and thus harm whatever influence you hope to exert here.

    The problem you’ve created for yourself is th persona you adopted in, say, April of 2007, when you carpet bombed numerous less specialized blogs with the following dross, already stale when you repeated it:

    “Forget all the junk science by so-called experts that are all in on the multi-billion dollar ‘climate research scam’.”

    “Let’s hope things will get warmer, rather than colder. We don’t need another ice age.”

    “Forget all the self-righteous calls for action by power-hungry politicians.”

    I’m sure you’d prefer the history of a selective portion of your other writings to be forgotten, here at least, but that history part-and-parcel of what you’re up to here. It’s necessarily involved in judging what you write, something referred to in jurisprudence as “caput”, the whole person. You’ve created a personal history for yourself in one place that is entirely at variance with what you’ve made elsewhere. Yet the two histories you’ve made are linked where you stand now.

    You’re a person who is clearly able to competently express himself with the written word; I’m sure it was no accident when you wrote:

    ‘The politicians and bureaucrats love the idea of “carbon taxes”, higher taxes on fossil fuels, “carbon footprint offset” schemes, etc., because it gives them more money to spread around (and more power).’

    You’ve also demonstrated your ability to make facile use of publications to bolster an argument. So I’m sure that if you have a source document for the assertion I’ve just quoted, you’ll display it here. Just so for:

    ‘It’s [man made climate change research] driven by an estimated 2.5 to 4 billion dollars per year in climate research grants, with the grants going selectively to those scientists who make the most disastrous predictions.’

    Can you say where the evidence is on which you base that claim? It’s rather important, for what you’re saying by extension is that the proprietors of this site are money-grubbing cynics.

    Comment by Doug Bostrom — 16 Jul 2009 @ 4:49 PM

  229. Kevin McKinney (#206) Why all the numbers? We all know it’s generally warming. Science is trying to find out why. (And how much of a contribution we might be making).

    Comment by simon abingdon — 16 Jul 2009 @ 4:50 PM

  230. Also despite prolonged solar minimum.

    Comment by David B. Benson — 16 Jul 2009 @ 4:57 PM

  231. 192 gp2 says, “It’s just 1 month…but el nino condition are at the begin and NCDC ocean anomaly for june is already the highest of the time series:”

    But UAH says June has a ZERO anomaly. Anybody have an explanation for the difference?

    Comment by RichardC — 16 Jul 2009 @ 6:03 PM

  232. Chris #221,
    Concerning the CLOUD experiment at CERN, you wrote in part:

    “…BobFJ, it’s not really a big experiment! The experiment involves filling a chamber with an atmosphere mix containing trace O3 and sulpher dioxide, using UV to convert sulpher dioxide into sulphuric acid and using a gamma ray source to induce nucleation particles that are detected with a particle detector…”

    Here is part of a CERN release, dating I think from 2006

    The CLOUD experiment involves an interdisciplinary team of scientists from 18 institutes in 9 countries, comprised of atmospheric physicists, solar physicists, and cosmic-ray and particle physicists. The PS provides an artificial source of ‘cosmic rays’ that simulates natural conditions as closely as possible. A beam of particles is sent into a reaction chamber and its effects on aerosol production are recorded and analysed.
    The initial stage of the experiment uses a prototype detector, but the full CLOUD experiment will include an advanced cloud chamber and a reactor chamber, equipped with a wide range of external instrumentation to monitor and analyse their contents. The temperature and pressure conditions anywhere in the atmosphere can be re-created within the chambers, and all experimental conditions can be controlled and measured, including the ‘cosmic ray’ intensity and the contents of the chambers.

    http://public.web.cern.ch/public/en/Research/CLOUD-en.html

    Since then, the experiment has advanced through various stages, and facilities, and is now called CLOUD-09. Here is an extract (page 43 of 44) from “CERN Colloquium, 4 June 2009” Lots of info there!

    CLOUD plans
    • 2009:
    * commission CLOUD-09
    * study H2SO4-H2O nucleation with and without beam
    * reproducibility of nucleation events
    * PTR-Mass Spect. to measure organics at 10 pptv level
    * new ion-TOF Mass Spect. for ion characterisation
    • 2010:
    * commission thermal system (-90C → +100C)
    * study H2SO4/water + volatile organic compounds with
    and without beam
    * temperature dependence (effect of altitude)
    • 2011-2013:
    * extend studies to other trace vapours, and to cloud
    droplets & ice particles (adiabatic expansions in chamber)

    http://indico.cern.ch/getFile.py/access?resId=0&materialId=slides&confId=52576

    You also wrote:

    That’s not to say that the solar – climate effects aren’t complex. However there isn’t really much evidence for the Svensmark hypothesis at all, although you wouldn’t know it from the relentless self-publicising from some quarters!

    Well maybe this 7-year experiment will find the evidence to support the hypothesis?

    Comment by BobFJ — 16 Jul 2009 @ 6:21 PM

  233. But UAH says June has a ZERO anomaly. Anybody have an explanation for the difference?

    Remember that they use a different baseline, for one thing.

    But they also have a history of showing a drop in their computation of anomaly every summer.

    It’s not known why, but if you look at the graphs in the article I link, you can see it’s extreme compared to GISS, HADCrut and RSS.

    Comment by dhogaza — 16 Jul 2009 @ 6:56 PM

  234. chris @ #132 14 Jul 2009 at 9:32 am:

    That’s not really correct Alex.

    Well, what you’ve written sounds very plausible; I had a look at Moberg. But after a while I realised that, hangon, it is correct what I wrote; I’ve seen Ray Pierrehumbert himself say so here at RealClimate in a discussion with Nir Shaviv that, yes, the little ice age really is still a bit of a mystery.

    This was Ray Pierrehumbert (20 May 2006 @ 1:21 am, ‘Thank you for emitting’ comments thread) in a discussion with Nir Shaviv:

    Nir, there is nothing wrong with thinking about possible impacts of cosmic rays on climate. Who knows, someday, something might come of it. We sure could use some new ideas about the Little Ice Age, since it’s hard to do that with straight solar effects, even allowing for ozone feedbacks and spectral variations.

    Now I’m sorry but says what it says: we haven’t explained the little ice age yet. And it is a fact (no?) that the temperatures really did fall over a number of centuries to correspond in some completely mysterious way with the Maunder Minimum (who knows, maybe it’s just a coincidence?). But surely, if it took a long time for the temperatures to fall, and we don’t know why, who can believe that without the human impact of CO2, they would have just popped back to where they were previously one morning?

    Finally, the main point I raised hasn’t been touched really by anyone.

    Alex De Visscher said #110 14 Jul 2009 at 12:13 am

    The choice of 1979-1997 might not have been intended as cherry-picking, but it is unfortunate choice nonetheless.

    I agree, it’s a most unfortunate choice because that’s the period in the last 150 years where the gradient of the temperature increase has been steepest. Yet this entire global warming debate is precisely about establishing true gradient of the underlying GHG signal. Some have argued (e.g. Douglass, Lindzen) that the gradient of the underlying GHG signal is quite low. Most argue that it is much steeper. I don’t think anyone has argued that its true steepness is coincident with that of the steepest increase of all, viz. 1976-1998.

    Meanwhile, the ‘steepness’ of the underlying GHG signal has been largely established by computer model runs that made assumptions about the radiative properties of aerosols (e.g. Kiehl 2007). The Tsonis & Swanson theory, if true, would suggest that the cooling of the 1970s had little to do with aerosols, and would invalidate those model runs that showed that the models can reproduce the 20th century surface temperature record. None of those models assumed a Swanson & Tsonis theory of synchronisation of multidecadal ocean cycles to explain the the cooling of the 1970s. Rather, they all assumed radiative properties of aerosols to explain this. Thus, this theory would render all of those runs as invalid, and would call into question again the strength of the water vapour feedback, and the true value of climate sensitivity to CO2.

    [edit]

    *Reference: Kiehl, J. T. (2007), Twentieth century climate model response and climate sensitivity, Geophys. Res. Lett., 34, L22710, doi:10.1029/2007GL031383.

    Comment by Alex Harvey — 16 Jul 2009 @ 7:56 PM

  235. Kevin McKinney says:

    “With all due respect, I would say that the “trend since 2001″ is statistically meaningless”

    No. The trend from 2001 is not statistically meaningless. GISS surface data shows a change from a statistically significant warming trend to 2000 and then a reduction to a statistically insignificant warming from 2001 (Using a Generalised Linear Model). For the lower troposhperic data from satellites the trend becomes a statistically significant decline (p<=0.01).

    Comment by Richard Steckis — 16 Jul 2009 @ 8:23 PM

  236. 233 dhogza says, “Remember that they use a different baseline, for one thing.”

    Yes, though slope isn’t so relevant when one value is 0 and the other is 1.

    Thank you for the article. It was exactly what I needed. The 0 has significant flaws.

    Comment by RichardC — 16 Jul 2009 @ 9:03 PM

  237. Simon, if you look at some of the posts above, I think you’ll see that perhaps not all of us do think it is warming. (And others of us know folks who don’t think so–in fact #12 above asks for talking points.)

    I think evidence of a “pause” in warming is still pretty thin, personally. Evidently, Richard Steckis (7/16, 8:23 PM) disagrees.

    Richard, how did you pick the inflection point of 2001?

    You know quite well that a “trend” of eight years duration in a signal this noisy is–well, bubkes, to go back a couple of posts. Or “well within the expected variability,” if you prefer–despite Dr. Swanson’s caution in invoking that term

    Comment by Kevin McKinney — 16 Jul 2009 @ 9:09 PM

  238. 223, Dhogaza–The discrepancy between trop & surface isn’t just UAH, though the annual cycle in UAH you note exacerbates it. It’s pretty marked in RSS, too–June was hugging the median of the data, which just dramatizes how paltry the .08 anomaly is.

    The surface/trop discrepancy is not new in June, either–we saw the same pattern, albeit a bit less markedly, in May. It’s a puzzle, to me at least. Why would the troposphere cool as the surface warms?

    Comment by Kevin McKinney — 16 Jul 2009 @ 9:36 PM

  239. I guess I should have noted that what Wayne says is true–the RATPAC data shows a considerably higher anomaly for the mid-trop; I don’t know what to make of that, either.

    (I should probably also clarify that my previous comment was talking about low trop–some of the previous comments referred to mid-trop, so “confusion alert!”)

    Comment by Kevin McKinney — 16 Jul 2009 @ 9:42 PM

  240. Re: #234 (Alex Harvey)

    Referring to the period 1979-1997, you state:

    I agree, it’s a most unfortunate choice because that’s the period in the last 150 years where the gradient of the temperature increase has been steepest

    This is not correct. There are equally long periods both before and after with considerably higher warming rate. In fact the period 1979-1997 shows one of the lowest warming rates in the modern (post-1975) GISS record; see this.

    Re: #235 (Richard Steckis)

    GISS surface data shows a change from a statistically significant warming trend to 2000 and then a reduction to a statistically insignificant warming from 2001

    Of course the trend since 2001 isn’t statistically significant; if you make the time span short enough statistical significance always disappears. Your statement is meaningless.

    For the lower troposhperic data from satellites the trend becomes a statistically significant decline (p<=0.01).

    No, it doesn’t, neither for RSS nor for UAH data.

    Comment by tamino — 16 Jul 2009 @ 9:48 PM

  241. http://julesandjames.blogspot.com/2009/07/yet-more-on-decadal-prediction-and.html
    “… 0.15C/decade is a more reasonable estimate of the forced trend, there is no evidence for any major change in this post 1998 and I don’t expect to see any such major change….”
    http://julesandjames.blogspot.com/2008/04/has-global-warming-stopped.html
    http://3.bp.blogspot.com/_8N7U3BAt9Q4/SBWGRmlJN9I/AAAAAAAAAK8/ibm-JrdYwv0/s1600-h/GWtrends.gif

    Comment by Hank Roberts — 16 Jul 2009 @ 10:12 PM

  242. Now I’m sorry but says what it says: we haven’t explained the little ice age yet.

    You do realize, of course, that the comment was made in the context that Real Science doesn’t show a *global* LIA, and he’s talking about our not being able to fully explain the regional LIA that actually doesn’t impact the long-term global record to the degree touted by denialists.

    Right? You understood that, right? Please don’t disillusion me by making it clear that I’m overestimating you.

    Comment by dhogaza — 16 Jul 2009 @ 11:02 PM

  243. Yes, though slope isn’t so relevant when one value is 0 and the other is 1.

    If that bothers you, use Kelvin. Earth ain’t been at 0K ever.

    Comment by dhogaza — 16 Jul 2009 @ 11:03 PM

  244. The trend from 2001 is not statistically meaningless… a reduction to a statistically insignificant warming from 2001

    I see. So statistically insignificant is now statistically significant?

    Gack.

    Comment by dhogaza — 16 Jul 2009 @ 11:05 PM

  245. Tamino #240:

    Thank you for the clarification and the article at your blog.

    Do you know if there is a publicly available comparison of all 20 year trends in the 150 temperature record, i.e. 1850-1890, 1851-1891, … 1988-2008?

    I am sure that in some of these 20 year trends we’ve seen periods of cooling (again I am not a scientist but it seems quite obvious just from eye-balling the charts).

    Thus the point would still remain — 20 years is a very short trend. A 20 year period has been chosen that shows warming. If other periods show less warming, or even cooling, how can this particular period not be cherry-picked?

    Comment by Alex Harvey — 16 Jul 2009 @ 11:57 PM

  246. Hi there,
    If Swanson’s hypotised 1997/8 step change is true, figure 1 shows, that the model trend’s are way off (the only fit the measured temperature in the short interval around the jump)
    The “non-cherry picking trend” is about about half the 2K/century.
    Ironically the flat red line might also be wrong, since it seems we are getting another El Nino-jump this year.
    That would mean 2 out of 3 wrong, where the one correcct is the measurement and the two others are the predictions . .
    All the best regards,
    LoN

    Comment by Laws of Nature — 17 Jul 2009 @ 12:52 AM

  247. First, I apologize for not reading the thread, I’m pressed for time this week. I just wanted to throw my two cents in and hope it has some relevance.

    While state changes in complex systems can happen, one must consider the capacity of forcing and smaller scale feedbacks. However the overriding forcing (parent system) has greater capacity to bias internal forcing (short term sub system bias).

    If the overall climate system was in or near a neutral state, decadal variations such as oceanic and solar would have greater capacity to influence a state change on a more significant scale (especially when combined).

    Since the current parent climate forcing is positive, not negative, the parent system can reasonably be expected to override the sub system variations (even when combined, though that is the question at hand – is it or isn’t it?).

    The main question is can, or does, the sub system variations combined have the capacity to override the parent system forcing on a decadal time scale and in a meaningful manner?

    I would tend to believe that it can, but that the parent system forcing of course would win in the end.

    The main question here is are enough of the internal systems considered and are they considered in a meaningful manner to yield reasonable results in the expectations?

    Examining these internal (sub-system forcings) will likely yield better understanding of the state change capacity and increase predictability of influence. This, in my mind, is a bridge of understanding that enables better predictability of climate forcing as it approaches the area of weather (shorter than 30 years), and is a good step towards understanding the major internal systems on decadal scales.

    From a general systems view the sub systems, such as short term ocean and solar, can trigger a state change under certain conditions, unless other sub systems or the parent system override. Arctic exposure combined with solar increase in the next 6 to seven years may have a significant impact on preventing a cooling period lasting till 2020. That combined with the parent system positive forcing bias will likely rule the impacts, in my opinion. Dark ocean in the Arctic increasingly exposed can have a pretty strong effect enhancing the Arctic amplification.

    Will be interesting to learn more about the combined subsystem bias and affects on forcing on these shorter time scales.

    If all this has been discussed I apologize. Will try to catch up soon.

    #235 Richard Steckis

    For perspective on 10 years of warming/cooling take a look at:

    http://www.ossfoundation.us/projects/environment/global-warming/myths/global-warming-stopped

    Comment by John P. Reisman (OSS Foundation) — 17 Jul 2009 @ 1:24 AM

  248. Hank Roberts, Reur 210:

    If you were to read my 183 with more care, you should be able to see that the core of my post was that the current “pause” in warming is remarkably similar to that which occurred around 1940. I notice that you make no comment, (do not disagree), with this observation. Instead you chose to denigrate the K & L 2003 paper that I secondarily put-up as what I know as the earliest reference to an apparent ~60 year cycle, which, by strange fortune they forecasted rather well, from back in 2003, what we are seeing right now .
    OK; let’s do a deal! Forget the L & K 2003 paper and just study the first figure that I posted in 183. If you don’t understand it then try this mark-up of Hadcrut through 2007, that I did for discussion elsewhere, a year ago. Some of it is OT for this issue, but please read the notes highlighted by the green boxes.
    http://farm4.static.flickr.com/3223/3049043899_af72413e2f_o.jpg
    It would be a stronger presentation if updated for the relatively cold year of 2008, but hopefully you will get the idea.
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    Regardless of the deal I propose; to ignore K & T, and just let the core issue I raised stand on its own, I concede that the K & T 2003 paper that I cited on the second figure in my 183 is hardly going to set the world on fire. One difficulty with it is that they show a nice clean major sine wave 62-year cycle which can never be proven, partly because of lesser cycles such as PDO superimposed on it. However, that is not to say that their conceptual observation is invalid, (cause unknown), although the fact is that it fits rather well to the current “pause” in warming, and also to that of around 1940. Furthermore, their forecast, fitting what we see today, was made back in 2003 and thus has not been contradicted.

    [edit]

    Comment by BobFJ — 17 Jul 2009 @ 1:58 AM

  249. “I see. So statistically insignificant is now statistically significant?

    Gack.”

    If we’re going to be raw empiricists about this, which I very much hate:

    It’s what we call a “changepoint”, where the data go from being well described by one (statistical, not physical) model to another. What would be interesting, and I don’t have time for it tonight, would be to compare one-changepoint to no-changepoint models here. A good starter no changepoint (statistical) model would be ordinarly linear regression for the whole set, and a good one changepoint model would be ordinary linear regression for part of it and a flat line for another part; compare the two using Schwarz Information Criterion or Akaike Information Criterion.

    Yes, I know that the ordinary least squares linear regression is not the correct method for these data, as the noise is probably autoregressive, but this is a ‘blog post. And I don’t really know how to do changepoint analysis using nonparametric methods (e.g. Spearman ranks correlation).

    Comment by Ben Kalafut — 17 Jul 2009 @ 2:52 AM

  250. “Mark (#211) “Why are you assuming that the only effect on temperature is CO2?” I’m not. (But the President of the United States seems to think it’s important).

    Comment by simon abingdon ”

    No, it is you.

    You stated that a question that is only relevant if you believe CO2 is the only component.

    NOTE: when it comes to mitigation, we can’t all go paddling out in the ocean to unto an El Nino event. Nor can we create sunspots.

    But what we CAN do is stop adding CO2.

    Hence when it comes to MITIGATION, CO2 is the biggest and best item to modify.

    But please tell us where mitigation of temperature change is temperature change.

    The gymnastics in logic to do so should be entertaining…

    Comment by Mark — 17 Jul 2009 @ 3:04 AM

  251. Doug Bostrom

    Lots of philosophical talk there, Doug, but all a bit off-topic here.

    Max

    Comment by manacker — 17 Jul 2009 @ 3:38 AM

  252. Hank Roberts

    You asked: “How long do you need to collect temperature data to say with statistical confidence that there is either an up or down trend, given the variability we know about?”

    I’d say a century would be a good start. 8-1/2 years (2001-2009) is definitely too short, as is 30 years (1976-2005).

    Max

    Comment by manacker — 17 Jul 2009 @ 3:41 AM

  253. manacker writes:

    The recorded fact is that the period 1910-1944 saw a linear warming of 0.53C (Hadley), 1944-1975 saw a very slight cooling and 1976-2000 (or 2005) saw warming of 0.37C (or 0.43C) (also Hadley). The warming has been interrupted, although the current years are still among the warmest recorded, as has been noted above.

    Prior to that, the short period right after modern measurements started showed a cooling trend (1850-1857). This was followed by a warming period from 1858 to around 1879, which was followed by a cooling trend from 1880-1909.

    The fact that you can refer to 1850-1857 as a “trend” shows you don’t know what a trend is or how to measure it. Until you learn some basic statistics, your analysis isn’t very useful.

    Comment by Barton Paul Levenson — 17 Jul 2009 @ 4:30 AM

  254. Mike,

    That coefficient should be 5.35 (Myhre et al. 1998), not the earlier value of 6.3.

    [Response: Yes, please note my own correction of this error further up in the comment thread, including the sign error (negative would describe the change in upward long wave flux from the surface, which is the opposite of what we usually mean by the 'forcing'). This is starting to feel a bit like the cover sheets on the TPS reports in 'Office Space' ;) -mike]

    Comment by Barton Paul Levenson — 17 Jul 2009 @ 4:37 AM

  255. max writes:

    Your analysis (206) of UAH temperature anomalies of the 90s vs. the 00s is interesting, and is no doubt correct.

    Another way of looking at it is the method preferred by IPCC: determine a linear trend line over the period measured.

    Doing it this way shows a linear cooling rate of around 0.1°C per decade on average over the 4 main records: (Hadley, GISS, UAH, RSS) from January 2001 to today (the 21st century, so far).

    How long this trend will continue is anyone’s guess, as is the warming rate that will ensue when the current warming interruption has ended.

    A “trend” has to have a statistically significant slope, max. Read:

    http://BartonPaulLevenson.com/VV.html

    Comment by Barton Paul Levenson — 17 Jul 2009 @ 4:38 AM

  256. Tamino is right when he writes (240):

    “There are equally long periods both before and after with considerably higher warming rate.”

    The period 1910-1944 lasted 35 years with a linear warming rate of 0.154°C per decade and 0.54°C over the period (Hadley).

    The period 1858-1879 was a bit shorter at only 22 years with a linear warming rate of 0.173°C per decade and 0.38°C linear increase over the period.

    Then there is the well-studied period 1976-2005, with a linear warming rate of 0.143°C per decade and 0.43°C linear warming over the 30-year period.

    But due to all the internal variability and intermittent cooling periods, it probably makes sense to look at the overall linear trend, which was 0.041°C per decade and 0.65°C over the entire 159-year period.

    Max

    Comment by manacker — 17 Jul 2009 @ 6:55 AM

  257. dhogaza (242)

    Were the LIA and MWP global or not?

    Since there was neither a global network of surface thermometers nor global satellite measurements of tropospheric temperatures, we need to resort to proxy data.

    But let’s assume that there had been a network of surface thermometers (as there are today). Let’s assume that the LIA (or MWP before) was restricted to Eurasia and the North Atlantic (where there are extensive historical data pointing to both a strong LIA and a MWP).

    So if the coldest part of the LIA, for example, was on average 1.5°C colder over Eurasia and the North Atlantic than today, the globally and annually averaged reading would by definition also have shown a lower temperature than today, once the Eurasian and North Atlantic temperatures were averaged in statistically.

    So one could say that the LIA (and MWP) were, indeed, “global”, even if the temperatures were only strongly cooler (resp. warmer) in an extended geographical region, such as Eurasia and the North Atlantic, just as one can say that the current warming is global, even if some geographical regions do not show such a strong warming trend as others.

    Just another way to look at it.

    Max

    Comment by manacker — 17 Jul 2009 @ 7:20 AM

  258. In establishing what the long term trend is [or was] they “remove” the 1998 El Nino but don’t do anything about variations from previous El Nino’s and La Nina’s? It cannot be that only the 1998 Super El Nino effected temperatures. Removing one ENSO event instead of all ENSO events is cherry picking.

    Should they have removed volcano forcing as well? Since some of the cooling episodes mentioned in these comments were due to volcanos but the last 10 years of weather were not.

    [Response: We discussed an ENSO corrected time series last year. - gavin]

    Comment by D Robinson — 17 Jul 2009 @ 7:58 AM

  259. Rod B #220:

    Thanks, Martin for opening the door.

    What door? Don’t put words into my mouth please. Mike’s description was/is accurate (minus typoes), I just wanted to point out a perhaps more fruitful way to look at it.

    Comment by Martin Vermeer — 17 Jul 2009 @ 8:03 AM

  260. Tamino #242 Says:

    “Re: #235 (Richard Steckis)

    For the lower troposhperic data from satellites the trend becomes a statistically significant decline (p<=0.01).

    No, it doesn’t, neither for RSS nor for UAH data."

    Well. Yes it does. Would you like to see my R code. I don't know how you calculated it but GLM clearly shows a significant decline in temperature from 2001 to present (p <= 0.01). Of course I use monthly data.

    Kevin McKinney:

    2001 is the first year of the 21st Century. But that is not the reason I chose it. I chose it because it is the first year that the immediate influence of the La Nina that followed the super El Nino declined. It is well known that extreme El Ninos are often followed by deep La Ninas.

    Comment by Richard Steckis — 17 Jul 2009 @ 9:00 AM

  261. Brian Dodge says: 15 Jul 2009 at 9:44 pm

    “there is a very NOT hidden downward trend in ice; arctic summer ice cover, glacier mass, increasing Greenland yearly ice melt, and a march of disintegrating ice shelves further south around Antarctica.”

    It is so much less alarming, if one realizes, no ice has disappeared. It has merely transported it’s self, through the ocean and atmosphere to the southern pole.

    JUNE (month end averages) NSIDC

    1980 Southern Hemisphere = 13.2 million sq km
    1980 Northern Hemisphere = 12.3 million sq km
    Total = 25.5 million sq km

    2009 Southern Hemisphere = 14.4 million sq km
    2009 Northern Hemisphere = 11.5 million sq km
    Total = 25.9 million sq km

    Total ice extent remains relatively constant. A 400,000 sq km increase in sea ice area (30 yr. net ice gain) should balance out any thinning. Remarkably stable total ice (volume) results.

    This slinky toy action of polar ice has yet to be definitively explained. One of the perturbations in the earths “wobble” would be my best bet. Ocean oscillations and orbital variance are just as valid. What fascinates me, is that this tremendous mass transfer from one pole to the other, in itself, will/must perturbate the earth’s eccentricity etc.

    [Response: Even if this theory had the slightest connection to reality, there would be no perceptible mass change associated with floating sea ice. Ice sheets would be a different issue - but they are decreasing at both poles. - gavin]

    Comment by G. Karst — 17 Jul 2009 @ 9:18 AM

  262. Re #234

    That’s still not correct I think Alex – two errors:

    Firstly, the main point of my original post was to point out the error in your assertion that:

    Even the IPCC2007 has said somewhere, I believe, that the levels of CO2 were probably not high enough until about 1950 to have had much effect on the global average temperature. So I am having a lot of trouble in understanding how, in the Swanson & Tsonis theory, these authors can genuinely believe in an underlying “true forced warming signal” from GHG emissions that began 1850 and continues today

    It’s easy to determine (read their reports!) that the IPCC consider that the median value of the likely range of climate sensitivity to raised CO2 is near 3 oC (of warming per doubling of atmospheric CO2). There’s no controversy about the atmospheric concentrations near the time of the Maunder minimum (around 276) and the mid 20th century (310 ppm around 1940). The anthropogenic contribution to raised CO2 in this period is near 30 ppm. It’s straightforward to calculate a likely anthropogenic contribution to warming (280-310 ppm) is 0.45 oC at equilibrium. So we (and the IPCC!) expect a substantial contribution to warming before 1950.

    The second error relates to your statement just below and the aditional comments in your post #234

    It seems fairly reasonable to suppose that had humans emitted no CO2 at all, temperatures would have risen again anyway in the same pattern that they had fallen previously, i.e. gradually and over a number of centuries.

    Have a look at Moberg et al again. You’ll see that during the period before the so-called Medieval Warm Period (MWP) the paleoreconstruction give (N. hemisphere) temperatures around -0.4 oC below mid 20th century. They went up a tad during the MWP (to around 0 oC relative to mid 20th century) and fell to around -0.6 oC during the Little Ice Age (LIA).

    So, yes it’s quite reasonable to propose that when the reduced solar forcing and negative volcanic forcing (and whatever other factors that might have contributed to LIA cold) dissipated, the temperature would have slowly recovered to it’s pre-perturbation state. This state seems to have been a temperature around -0.4 oC below the mid 20th century level.

    One can draw pretty much the same conclusion from the recent paleoreconstruction of Mann et al. in PNAS [*].

    So my argument in post #132 applies as does your suggestion that the LIA cold was likely to have recovered by itself towards the pre-exisiting equilibrium state. It’s just that the pre-equilibrium state was (according to the paleoreconstructions) quite a bit cooler than the mid 20th century state. We can understand how the temperature rose well past that state (by perhaps around 0.4 oC) from our (and IPCC’s) understanding of the greenhouse effect. Your point about what Dr. Pierrehumbert said on a different thread is not relevant – the straightforward understanding of the recovery and overshoot from the LIA is independent of any causal mechanism(s) of the LIA.

    So again everything is quite consistent with your interpretation of Swanson & Tsonis theory, namely an underlying “true forced warming signal” from GHG emissions that began 1850 and continues today.

    M. E. Mann et al. (2008) Proxy-based reconstructions of hemispheric and global surface temperature variations over the past two millennia Proc. Natl. Acad. Sci. USA 105, 13252-13257

    Comment by Chris — 17 Jul 2009 @ 9:18 AM

  263. “it probably makes sense to look at the overall linear trend, which was 0.041°C per decade and 0.65°C over the entire 159-year period.

    Max”

    Except that 159 years ago, the amount of CO2 being produced by industry and man in general was much lower than it is today.

    Just ask ExxonMobil how much more oil they are dealing with than even 20 years ago.

    Or are they in on the great conspiracy too?

    Comment by Mark — 17 Jul 2009 @ 9:30 AM

  264. Gavin: “no perceptible mass change associated with floating sea ice.”

    Not a theory really, merely an observation. Your response is appropriate and somewhat valid. It does not, however, explain the phenomena. BTW “observations” do have a connection with reality. Slight or not. Thanks for discussing it with me.

    Comment by G. Karst — 17 Jul 2009 @ 10:16 AM

  265. “Of course I use monthly data.”

    And such data will have sqrt(12) times more noise in them.

    Therefore you need many more months.

    Note also that the data you’re using includes the effect of stratospheric cooling. What do you think the point of that will be?

    Here’s an idea: check the record for June this year.

    Find out the average temperature.

    Check to see if this June is cooler than many other Junes in the past 30 years.

    Now check the June figure in that graph.

    How many Junes are there that are warmer?

    Now why the lack of skepticism? That graph of yours is from wattsupwiththat. Originally Roy Spencer and a pal.

    Where he’s taken 11 instruments (there are more than that up there), mentions that AMSU-A is the most steady and then ignores

    a) what does he mean by steady?
    b) what about the other 11 less steady

    and then creates a graph with a zero that looks like the average temperature on the graph.

    Well of course the end point will come toward zero. If it moves away, the zero line will follow it slowly.

    Comment by Mark — 17 Jul 2009 @ 10:22 AM

  266. Mark

    It appears that you are confusing empirical evidence (physically observed temperatures) with possible causes for temperature increase.

    The warming period from 1858 to 1879 was certainly not caused by human CO2 emissions, but it was physically observed, nevertheless, as was the warming from 1910 to 1944, when there was hardly any human CO2.

    The 159-year record tells us that it has warmed in three multi-decadal “spurts” (of which the latest 1976-2005 period was one), with cooling periods in between, and an average underlying warming trend of 0.041C per decade.

    These are the physically observed facts. How one wants to explain these is another story, with or without ExxonMobil.

    Max

    Comment by manacker — 17 Jul 2009 @ 10:49 AM

  267. Re: #258 (Richard Steckis)

    You’re wrong. The GLM routine in R will compensate for non-Gaussian errors (if so specified), but will not compensate for autocorrelation.

    No, I don’t care to see your R code.

    Comment by tamino — 17 Jul 2009 @ 11:31 AM

  268. Mark says:

    “Note also that the data you’re using includes the effect of stratospheric cooling. What do you think the point of that will be?”

    No. It does not include stratospheric cooling. The data are from the AMSU TLT channel which maximises in the lower troposphere (approximate 1 – 2 km above the surface. The influence of the lower stratosphere is negligible for this channel.

    And no. The data do not have sqrt(12) times more noise in them. I do not know where that idea comes from. The more data you have the higher the degrees of freedom for the statistic. The higher the degrees of freedom the greater the confidence of the trend.

    Comment by Richard Steckis — 17 Jul 2009 @ 11:42 AM

  269. Manacker, any word on your assertions about government and the scientific community? Slander or true? Baseless or founded? Paranoid or grounded in reality? Have you changed your mind?

    Comment by Doug Bostrom — 17 Jul 2009 @ 12:06 PM

  270. Doug Bostrom

    Sorry, your query is OT at the time. We are discussing temperature trends, warming interruptions, etc.

    An open-minded person is always open to changing his/her mind as new data become available, right?

    Max

    Comment by manacker — 17 Jul 2009 @ 1:04 PM

  271. G. Karst

    On sea ice the June NSIDC data show that the losses in the Arctic are offset by gains in the Antarctic.

    Check:
    ftp://sidads.colorado.edu/DATASETS/NOAA/G02135

    Click June and then:
    N_06_area.txt for Arctic sea ice extent and area
    S_06_area.txt for Antarctic sea ice extent and area

    Max

    Comment by manacker — 17 Jul 2009 @ 1:10 PM

  272. Doug, it’s all #1′s…

    Except the last one. There’d need to be something to change for a start…

    Comment by Mark — 17 Jul 2009 @ 1:13 PM

  273. “And no. The data do not have sqrt(12) times more noise in them. I do not know where that idea comes from.”

    Binomial statistics.

    The difference of each month around the year average is much higher than the change between each year adjacent.

    Comment by Mark — 17 Jul 2009 @ 1:14 PM

  274. Richard,

    The GISS surface data is broken. There is a significant data anomaly cause when NOAA-14 was replaced with NOAA-16 (10/01). [edit]

    [Response: The GISTEMP data is not the same as the ISCCP analysis - it is instead derived from met stations. The issues with NOAA 14 and 16 are relevant to the ISCCP data which is very clearly caveated to indicate that it should not be used for trends because of the inter satellite calibrations and inhomogeneities. - gavin]

    Comment by co2isnotevil — 17 Jul 2009 @ 1:18 PM

  275. Manacker, sorry I missed your earlier post, wherein you said:

    “Lots of philosophical talk there, Doug, but all a bit off-topic here.”

    “There” being here, presumably:

    http://www.realclimate.org/index.php/archives/2009/07/warminginterrupted-much-ado-about-natural-variability/#comment-131348

    Consider:

    –You’ve established a clear track record of what a reasonable person would consider to be a disingenuous and self-contradictory approach in your communications style. You employ demagogic, inflammatory rhetoric against climate science and climate scientists when attempting to influence selected audiences. Elsewhere you then engage in seemingly reasonable and judicious discourse with members of those same groups you disparage. You apparently expect to be treated as a peer in both arenas.

    –You’ve produced a history of making broadly accusatory pronouncements of malfeasance and corruption germane to the general topic under discussion here. Specifically, you have made statements that a reasonable person would interpret as being accusations of climate scientists reporting scientific results that have been shaped by avarice on the part of climate scientists. You are charging these scientists with being guilty of professional misconduct. At the same time, you do not appear able to verify the accusations you’ve leveled.

    –The history of your behavior, the history that you have created, would lead a reasonable person who is bothered by the deficiencies you have displayed to cast a jaded eye on opinions and statements you may express concerning the topic under discussion here. Everything you say about climate science must therefore be assessed not only on the superficial merits of your words but also with the certain knowledge as established by you yourself that you appear either to suffer from derangement in your perceptions or have a habit of practicing deceit in your communications.

    As I say, this is the appearance you give. You’ve made bold and astounding claims about this topic for which you appear to have no evidence. Perhaps you can change that appearance by justifying your demagoguery with some evidence.

    It’s really not about you specifically in any case. You’re a phenotype of what is commonly termed a “denialist”, with a particularly rich and generous historical track record available for scrutiny. Viewed from that perspective, you’re highly topical.

    Comment by Doug Bostrom — 17 Jul 2009 @ 1:19 PM

  276. re #266

    The warming period from 1858 to 1879 was certainly not caused by human CO2 emissions, but it was physically observed, nevertheless, as was the warming from 1910 to 1944, when there was hardly any human CO2.

    manacker, there was rather a lot of anthropogenic CO2 in the period 1910-1941. The anthropogenic increase in atmospheric CO2 gave a rise from around 280 ppm in the late 18th century to around 297 ppm in 1900 to nearly 310 ppm around 1940 [*]

    The total expected anthropogenic global temperature contribution over this full period within a climate sensitivity of 3 oC is easily calculated. It’s 0.44 oC at equilibrium.

    So human emissions made a very significant contribution to the temperature rises during the periods you specified. In fact they could account for most of the temperature increase during these periods. Of course the anthropogenic contribution was “mixed in” with natural solar and volcanic contributions so one doesn’t expect to observe a simple temporal relationship, any more than we expect to see a simple relationship nowadays (which is what this thread is largely about of course).

    [*]D. M. Etheridge et al (1996) “Natural and anthropogenic changes in atmospheric CO2 over the last 1000 years from air in Antarctic ice and firn J. Geophys Res. 101, 4115 -4128

    Comment by chris — 17 Jul 2009 @ 2:14 PM

  277. Thomas Lee Elifritz says: http://www.math.sdsu.edu/AMS_SIAM08Shen/Abramov.pdf

    Note that the largest disturbance in the examples began to degrade within 100 days.

    Comment by RichardC — 17 Jul 2009 @ 3:03 PM

  278. This warming pause I suspect will be for sometime even if not for another 12 years.

    Comment by Jacob Mack — 17 Jul 2009 @ 3:22 PM

  279. Doug Bostrom (275)

    You are getting a bit repetitive, Doug, but still OT.

    Try getting back to the topic here, which is the “warming interruption” since 2001 and its significance (if any) in the long-term picture.

    Max

    Comment by manacker — 17 Jul 2009 @ 3:35 PM

  280. Alex Harvey (234) — As I understand it, LIA was almost global in extent, (It seems that Antarctica either did not participate or maybe had a little warm reversal, I’m unsure.)

    The causes include significant volcanic activity and the Maunder and Dalton Minima. Both of these lead to less insolation. When done, the temperature retuns to something more normal. See
    http://tamino.wordpress.com/2008/10/19/volcanic-lull/

    ============
    Regarding the subtopic of global temperature trend over the instrumental period (beginning at the earliest in 1850 CE), see the UPDATE on that same thread over at Tamino’s Open Mind. I’ll have something more to post about it later.

    Comment by David B. Benson — 17 Jul 2009 @ 3:47 PM

  281. Re: 231
    MSU records temperature of the entire troposphere with different weights, this is not the same as global ocean surface temperature…for instance free tropical tropospheric temperature depends upon heat transfer due to deep convection i.e. a relative small area with high sst and strong deep convection may influence the free troposheric temperature accross the tropics much more then large area with high ssta but lower sst.
    see: http://ams.allenpress.com/archive/1520-0442/15/18/pdf/i1520-0442-15-18-2702.pdf

    “It is expected that the free tropospheric
    temperature should be sensitive primarily to SST anomalies in regions in which the mean SST is
    high and deep convection is frequent, rather than to the tropical mean SST.”

    Furthermore there are major uncertain for long term trend in the tropics…different analysis shows very different trend and UAH trend is the lowest.
    An interesting paper that covers uncertain and propose a new intercalibration methods for MSU:
    http://www.star.nesdis.noaa.gov/smcd/emb/mscat/mscat_files/Zou.2009.ErrorStructure.pdf

    “However, temperature
    trends obtained from these observations are still
    under debate; different results are obtained by different
    investigators. Further investigation is required to reconcile
    these differences.”
    They found a global ocean T2 trend of +0.21K/decade between 1987 and 2006 compared to +0.14K/decade (RSS) and +0.08K/decade (UAH).

    Comment by gp2 — 17 Jul 2009 @ 3:53 PM

  282. Chris (276)

    You wrote:

    “there was rather a lot of anthropogenic CO2 in the period 1910-1941. The anthropogenic increase in atmospheric CO2 gave a rise from around 280 ppm in the late 18th century to around 297 ppm in 1900 to nearly 310 ppm around 1940 [*]
    The total expected anthropogenic global temperature contribution over this full period within a climate sensitivity of 3 oC is easily calculated. It’s 0.44 oC at equilibrium.”

    Sorry, Chris, but your calculation is incorrect.

    Let’s do it again
    C1 = 297 ppmv (concentration in 1910)
    C2 = 310 ppmv (concentration in 1944)
    C2/C1 = 1.04
    ln(C2/C1) = 0.0428
    ln(2) = 0.6931
    dT (2xCO2) = 3.2°C (at equilibrium)
    dT (1910-1944) = (3.2 * 0.0428) / 0.6931 = 0.20°C (at equilibrium)

    So anthropogenic CO2 could only have caused 0.20°C warming over the period (not 0.44°C), while 0.54°C were physically observed.

    Max

    Comment by manacker — 17 Jul 2009 @ 4:00 PM

  283. G. Karst says 17 Jul 2009 at 9:18 am;
    “Total ice extent remains relatively constant. A 400,000 sq km increase in sea ice area (30 yr. net ice gain) should balance out any thinning. Remarkably stable total ice (volume) results.”

    But–
    “Because sea ice does not stay in the Antarctic as long as it does in the Arctic, it does not have the opportunity to grow as thick as sea ice in the Arctic. While thickness varies significantly within both regions, Antarctic ice is typically 1 to 2 meters (3 to 6 feet) thick, while most of the Arctic is covered by sea ice 2 to 3 meters (6 to 9 feet) thick. Some Arctic regions are covered with ice that is 4 to 5 meters (12 to 15 feet) thick.”
    http://nsidc.org/seaice/characteristics/difference.html

    If one only remembers to subtract the ice lost by the collapse of Larsen B-(3,250 km^2) and Wilkins-(more than 2000 km^2 so far; about 10k km^2 when it all disappears) ice shelves, more than 200 meters thick; or the equivalent of 500,000+ square kilometers at 2 meter thickness; then the plus 400,000 km^2 sea ice area doesn’t “balance out any thinning”.

    When one considers the following:
    “Satellite radar altimeter measurements show that between 1992 and 2001 the Larsen C Ice Shelf lowered by up to 0.27 ± 0.11 meters per year.”
    http://www.sciencemag.org/cgi/content/abstract/302/5646/856

    “In the last 5 years, the picture of a slowly changing Antarctic ice sheet has radically altered. It is now realised that ice shelf basal melting may account for up to one third of the loss from the grounded ice; extensive, rapid thinning is occurring in one part of the West Antarctic ice sheet interior; and the collapse of the Antarctic Peninsula ice shelves is accelerating the grounded ice discharge.”
    http://www.scar.org/publications/bulletins/146/ismassworkshop.html

    “In order to better constrain the coastal element of the problem, Rignot et al. have analyzed satellite interferometric synthetic-aperture radar observations of Antarctica’s coastline from 1992 to 2006 to estimate ice flux to the oceans. … Ice mass loss from the coasts increased by 75% over the period of the study.”
    http://www.sciencemag.org/cgi/content/full/sci;319/5861/259d

    It is obvious that total ice volume is not “remarkably stable”, but declining.

    Perhaps the ice melting has resulted in a lower salinity surface layer in the seas surrounding Antarctica, which freezes more easily and extensively?

    Comment by Brian Dodge — 17 Jul 2009 @ 4:18 PM

  284. re #282

    careful manacker. You didn’t read my post correctly. My calculation of 0.44 oC corresponds to the anthropogenic contribution during the full period of late 18th century to 1940 (280 – 310 ppm).

    That encompasses both of the periods you specified. The anthropogenic contribution accounts for a large proportion of warming during this period. Since it’s mixed in with the natural variaiton (volcanic/solar) we don’t expect to observe a stesdy temperature rise that follows the excess CO2 forcing perfectly. But the warming contribution will be there.

    That’s relevant to your rather cherry-picked start date for the later warming period of 1910-1944. The cooling period previous to 1910 was most likely a result of extensive volcanic forcing, so that some of the post-1910 warming was a recovery from this.

    Your own calculation shows that your statements in post #266 are wrong. There was “human CO2″ in the periods you specified. This “human CO2″ did contribute to warming.

    Comment by chris — 17 Jul 2009 @ 5:17 PM

  285. Brian Dodge (283)

    Speculations on relative sea ice thickness in the Arctic and Antarctic are interesting, but not that relevant.

    Changes in floating sea ice (even including “dramatic” events, such as the collapse of Larsen B and Wilkins) have no substantial impact on sea levels.

    These are primarily of interest as they may affect surface albedo, and in that respect thickness has no impact, but it is total sea ice extent (or area) in both the Arctic and Antarctic that counts.

    Based on the latest NSIDC data for June, these appear to have been constant, with net losses in one region essentially offset by net gains in the other.

    Max

    Comment by manacker — 17 Jul 2009 @ 5:21 PM

  286. Max, re 282

    Your calculation is incorrect as well. The proper calculation is to first determine the power flux in and out of the surface, which for an average surface temperature of 288K is 390.11 W/m^2 from Stefan-Boltzmann. The forcing power (using the IPCC heuristic) is,

    5.35 * (ln(310/280) – ln(297/280)) = 0.23 W/m^2

    Add this to 390 (390.23) and convert back to a temperature, we get 288.02K, for a net increase of 0.042K. Now, the sensitivity coefficient of 0.8, which would predict a temperature increase of 0.18K from yet another heuristic, is after the effects of feedback. However, part of the problem today, is that the warming this heuristic predicts hasn’t happened, so the presumption is that this energy is hiding out some where and some should have been hidden back then too.

    Of course, this is all moot, because there’s a simpler explanation that is independent of CO2. Around 1910, there was record sustained level of low sun spot activity, the likes of which we haven’t seen since, and which resulted in significant cooling. This cooling rebounded as the sunspot activity increased up to it’s record high levels in recent history. Today, the current 11-year sun spot minimum is deeper than we have ever measured with modern techniques, but it remains to be seen if it will reach the depths of the minimum seen around 1910-1911.

    There’s an easy way to test this correlation, which is to plot monthly averaged sun spot numbers against the temperature record. I’ve done this as have others, but you will need to do this for yourself to believe it. I suggest plotting an 11-year running average of both temperature and the sunspot number.

    George

    Comment by co2isnotevil — 17 Jul 2009 @ 5:59 PM

  287. manacker 17 Jul 2009 at 3:35 pm

    “You are getting a bit repetitive, Doug, but still OT.”

    Not nearly as robotically, verbatim repetitive as you’ve been elsewhere, not to mention off-topic by your oddly elastic standards. How about your “A Layman’s Review of the latest IPCC report”, which you dumped regardless of context on at least half a dozen sites? That was a real gem of the pasty, bogus variety, containing as it did what appeared to be catchy talking points distilled from multiple sources, thrown together into a stream-of-consciousness rant and then inserted in multiple locations.

    That’s not the only time you’ve done that, either. I’ll spare everybody the details.

    Given the hopeless hole you earlier dug for yourself and seem doggedly reluctant to climb out of, I’m not surprised you’re insisting on remaining “on-topic” here. Your embarrassing past can’t really be put to rest without an explicit mea culpa and apology.

    After all, here you are, enjoying the hospitality of folks you elsewhere essentially called liars and charlatans. No wonder you’re skulking and would rather avoid discussing that uncomfortable topic. You’re dining in the house as a guest, but you shat in the yard as a vandal.

    Why not just say “Gee, I’m genuinely sorry, I was just wrong when I made a blanket accusation of theft directed at the climate science community, I’ve since come to realize that those words were hasty, ill-considered and had no foundation of truth”?

    Really nothing more to add here, other than a reminder that accountability in social matters is a form of algebra where it’s painfully obvious when an equation does not balance. At least you do consistently identify yourself; hats off to you for making it possible to sum you up.

    Comment by Doug Bostrom — 17 Jul 2009 @ 6:00 PM

  288. In #70 Ike Solem says:

    “Volcanic events are…are insensitive to the state of the ‘the climate system’.”

    I realize there are much higher-priority unanswered questions out there, but I’ve often wondered about this: If the Antarctic or Greenland ice sheets melt faster due to continued warming, one would think the disappearance of that ice would allow for faster isostatic rebound, and that in turn may have some impact on volcanism. And if so, one could then say there’s a global warming connection to volcanoes. But I agree with the gist of your post.

    Comment by Steve E — 17 Jul 2009 @ 7:03 PM

  289. Following up on my comment #280, assume a linear system (sorta dubious for climate, but the assumption means some suggestive answers are readily obtained by hand). Assume the very reasonable system response to a unit step function given in
    http://tamino.wordpress.com/2008/10/19/volcanic-lull/
    which has a LaPlace transform of the form
    1/s – 1/2(s+a) – 1/2(s+b)
    with a = 1 and b = 1/30 (using Tamino’s values) and where, for simplicity, the two weights are both 1/2, summing to 1 as required.

    Now for a ramp forcing, linearly increasing over time (as has been assumed in comments on this thread), the LaPlace transform is
    1/s^2 – 1/2s(s+a) – 1/2s(s+b)
    and the system response is, as expected, of the form
    k[t - c + transient]
    where the transient response function is initially c and decays as a sum of two dying exponentials. With b representing thirty years, one needs to take this transient respnse into account even for rather long intervals.

    The point is that it is not strictly correct to simply plug into the equilibrium response logarithmic equation to compute the temperature gain over any decadal, even centennial, interval. One needs to determine c depending upon a, b and the two weights. For the stated values, c is about 0.517.

    Now there is an arbitrary scale factor, k, to convert time to temperature. I suggest using parameter estimation methods on, say, HadCRUT3g to find the best fitting scale factor (for those who wish to carry out modestly accurate such comparisons between the historical record and the assumed linearization of the CO2 forcing). If one also uses paramter estimation simultaneously for k, a, b and the two weights, there are then five parameters to be esimated; not for the impatient or impersistent. As responses above have indicated, you’ll not be able to determine Charney sensitivity with any precision this way.

    Comment by David B. Benson — 17 Jul 2009 @ 7:50 PM

  290. Brian Dodge (283) makes reference to ice shelf collapse in Antarctica:
    May I point out that this phenomena and also the calving of icebergs are fundamentally mechanical fracturing failures. If you study the canyons developing in ice shelves, before break-up, they appear to run parallel to the influence of the ocean, primarily because of tidal and wave action, resulting in hinging at the sites of the canyons. As an engineer, I find it hard to see any climate change effect that would significantly accelerate this normal process. Changed wind strength or circulation? Increased melt within the canyons? Maybe…. but I doubt it.

    [Response: Actually, temperature increase has been shown to have a very pronounced effect on the breakup of ice shelves. It is indeed mechanical fracture that does the job, but what warming does is to form massive melt ponds at the surface, which then cause hydraulic fracture. --raypierre]

    Comment by BobFJ — 17 Jul 2009 @ 8:20 PM

  291. co2isnotevil (286) — Alas, correlation is not causation. Better, I opine, is to read Tung & Cabin (2008), available from Prof. Tung’s UW web site. There you will find an analysis of about 50 years of data and a determination that global temperatures go up and down over solar sunspot cycles. What is surprising is their technique shows considerably larger amplitude to the cycling than previous researchers have found.

    Comment by David B. Benson — 17 Jul 2009 @ 9:14 PM

  292. Martin Vermeer,
    Sorry, but I should have included you as an addressee having a special interest in my post 191 above, (the bit below the wiggly line)

    Comment by BobFJ — 17 Jul 2009 @ 9:18 PM

  293. Tamino #267 says:

    “You’re wrong. The GLM routine in R will compensate for non-Gaussian errors (if so specified), but will not compensate for autocorrelation.”

    You are right. Does your criticism apply to all the linear regressions that you present at your site? Do you always test for autocorrelation before presenting linear regression models?

    Comment by Richard Steckis — 17 Jul 2009 @ 9:56 PM

  294. Tamino #267

    Further. Do you suggest an alternative that corrects for autocorrelation. Perhaps GLS?

    Comment by Richard Steckis — 17 Jul 2009 @ 10:39 PM

  295. manacker says 17 Jul 2009 at 5:21 pm
    “These are primarily of interest as they may affect surface albedo, and in that respect thickness has no impact, but it is total sea ice extent (or area) in both the Arctic and Antarctic that counts.”
    The decrease in albedo is in the Arctic, where it’s summertime and the sun is shining; the supposedly compensating Antarctic increase in extent/albedo is occurring where there is much less or no insolation.
    (And I was specifically discussing the claim that “Remarkably stable total ice (volume) results.”, where thickness does count.)

    BobFJ says 17 Jul 2009 at 8:20 pm
    “I find it hard to see any climate change effect that would significantly accelerate this normal process.”
    Warmer temperatures cause larger and longer duration of surface melt on the ice shelves.
    Hydrostatic pressure from the ponding of meltwater on the surface of ice shelves causes cracks to propagate; shortly after the disappearance of meltwater ponds on the surface of Larsen B was observed, indicating that the cracks had gone full thickness, the shelf abruptly collapsed. Stress from tides, waves, and winds play a role (and the increase in the strength of the circumpolar vortex predicted by climate models probably contributed), but warming has set the stage for the demise of ice sheets that have existed for 6-10 thousand years. Start with http://earthobservatory.nasa.gov/Features/LarsenIceShelf/ to learn more.

    Comment by Brian Dodge — 17 Jul 2009 @ 10:46 PM

  296. @ David Horton 16 Jul 2009 at 3:35 am
    Re endlessly pushing a boulder up a hill – I think the phrase you’re looking for is “Sysyphean whack-a-mole”

    Comment by Brian Dodge — 17 Jul 2009 @ 10:55 PM

  297. BobFJ, would it safe to assume that as an engineer, you find it hard to see any climate change effect, and haven’t looked for anyone else’s work to inform your opinion?

    If you have read on the subject, what have you read?
    Have you searched (search box, top of page) here?

    Comment by Hank Roberts — 18 Jul 2009 @ 12:13 AM

  298. Further again,

    I tested the RSS time series from 2001 to present using ACF and PACF in R and could not find any significant autocorrelation or partial autocorrelation for that time series. This is even though the Durbin Watson test was significant (p<=0.001) with a DW statistic of 0.85

    Comment by Richard Steckis — 18 Jul 2009 @ 1:29 AM

  299. BobFJ #290, eh… “ice flow”… “basal melting”… “rapid thinning”… not just mechanics. You can read up on these things.

    Comment by Martin Vermeer — 18 Jul 2009 @ 1:33 AM

  300. BobFJ 17 Jul 2009 at 8:20 pm:

    “If you study the canyons developing in ice shelves, before break-up, they appear to run parallel to the influence of the ocean, primarily because of tidal and wave action, resulting in hinging at the sites of the canyons. As an engineer, I find it hard to see any climate change effect that would significantly accelerate this normal process.”

    Climate change effect? Temperature? Melting point of ice? Loss of mass? Reduction of beam cross section? Deformation of beam leading to strain and failure?

    Comment by Doug Bostrom — 18 Jul 2009 @ 2:40 AM

  301. Chris (284)

    The period 1910-1944 showed warming of 0.54°C, as observed by Hadley.

    While atmospheric CO2 figures for this period are based on estimates rather than hard empirical data, the CO2 increase over this period only “supports” a theoretical GH warming (at equilibrium) of 0.2°C (or 0.18°C as co2isnotevil has shown us in 286). Yet we saw an observed linear warming of 0.54°C over this period, or around three times that which could be explained at equilibrium by GH warming from CO2..

    This is what we are comparing here, Chris, not the net overall warming actually measured from 1850 to 1944 nor the theoretical GH warming we might have expected from 1750 to 1944.

    The solar explanation by co2isnotevil (286) may actually make more sense than trying to tie this all to human CO2 emissions.

    Max

    Comment by manacker — 18 Jul 2009 @ 3:24 AM

  302. Re 285
    “Changes in floating sea ice (even including “dramatic” events, such as the collapse of Larsen B and Wilkins) have no substantial impact on sea levels.”

    Not true. Whilst the collapse of an ice sheet in itself does not alter the sea level, what it can do is to speed up the flow of the glacier that was feeding it, leading to more ice going into the sea, which will raise the sea level at some point.

    All this was quite extensively discussed on this site just a couple of months ago, so you obviously have not been paying attention, Max.

    Comment by CTG — 18 Jul 2009 @ 3:26 AM

  303. “As an engineer, I find it hard to see any climate change effect that would significantly accelerate this normal process.”

    Because as an engineer you will work with higher tensile strength materials.

    As a denier of AGW you will then transfer this knowledge in egineering into climate science and not see any problems.

    Ice will extend into the ocean. Where there is water. Water that isn’t frozen. Now this ice will try to MAKE that water frozen, but this takes energy and the ice will get warmer.

    As it gets warmer, its strength reduces somewhat and localised melting will occur.

    Now tell me an engineering scenario when you have to build something that will be in contact with a molten version of itself quite extensively and for a long time?

    Comment by Mark — 18 Jul 2009 @ 3:27 AM

  304. manacker 17 Jul 2009 at 5:21 pm

    “Changes in floating sea ice (even including “dramatic” events, such as the collapse of Larsen B and Wilkins) have no substantial impact on sea levels.

    These are primarily of interest as they may affect surface albedo, and in that respect thickness has no impact, but it is total sea ice extent (or area) in both the Arctic and Antarctic that counts.”

    Strawman.

    You’re inserting the old, tired “if an ice cube melts, it does not affect the level of the water in the glass” canard, hoping it’ll distract attention from other important characteristics of the ice.

    I’m sure you noticed that Bryan’s post mentioned nothing about sea level, but you’re apparently hoping others don’t pick up on that.

    As to the primary interest of the data Bryan cited, what it’s telling us is a message about the qualities of the ice. You’re apparently asserting something along the lines of “Hey, I’ve given you a glass of Thunderbird, why are you complaining that you ordered a vintage varietal?” Sure, the ice is white, the wine is red, but is that the point? No.

    Comment by Doug Bostrom — 18 Jul 2009 @ 4:05 AM

  305. For some reason I can’t get past the spam filter trying to respond to RS’s #260. RS, you are artificially ballooning the number of points and significance by using monthly data when the proper time scale for temperature is about 30 years. It’s like me taking the temperature here at one-minute intervals from 6 AM to 9 AM. That gives me 181 points, which I then use to show a significant upward trend in temperature, proving that the oceans will boil in two days.

    Comment by Barton Paul Levenson — 18 Jul 2009 @ 4:31 AM

  306. Speaking of emerging trends and the need for oceanic monitoring, is anyone trying to organize international forces to design a joint global ocean monitoring network, or are we still peppering the issue with a hail of little BB’s?

    Comment by Steve E — 18 Jul 2009 @ 7:10 AM

  307. Raypierre, many thanks your response appended to my 290

    Response: Actually, temperature increase has been shown to have a very pronounced effect on the breakup of ice shelves. It is indeed mechanical fracture that does the job, but what warming does is to form massive melt ponds at the surface, which then cause hydraulic fracture. –raypierre]

    I’d like to learn more from you, as may too, other readers here.
    Are you able to point us to some references for quantification of “hydraulic fracture“.
    The reason I ask is that as a mechanical engineer, (as would I think some “rock engineers” = geologists), I find what you say to need some additional explanation and illustration.

    [Response: If melt water pools on the surface and finds a crack in the ice, there is a strong pressure at the bottom of the crack since the water is denser than the ice. Thus there is a strong pressure gradient that (as long as the water doesn't freeze) will work to further deepen the fracture. Ian Joughlin has got some good slides on the subject (perhaps they are online somewhere?). - gavin]

    Comment by BobFJ — 18 Jul 2009 @ 7:40 AM

  308. You make the point, that the recent cooling has no significance, as it is just a little bit of natural variability, but you give us a laughable short perspective from 1950 to today. If you would look at the climate variability starting at about 10000 years before today, You would see, that the whole so called” global warming” is well inside the natural variability. It was warmer than today during the roman optimum and the medieval optimum. If you would look into a time-scale of billions of years, You might well see, that a climate, that does not change, would be a very surprising oddity.

    [Response: You are mistaken if you think it is merely the fact that climate changes is the issue - it is not. The issue is why climate is changing and whether we can attribute changes to physical causes. You can't do it for periods that are too short because of the unforced variability, but you can for the long-term trends either recently (predominantly due to increasing GHGs), or over the Holocene (orbital forcing), or the whole Cenozoic (tectonically driven changes in circulation, weathering, outgassing etc.). - gavin]

    Comment by Jörg Schulze — 18 Jul 2009 @ 7:56 AM

  309. Bob_FJ (290)

    There seems to be differences of opinion as to whether global climate changes have much to do with glacial calving. Here are just three references:

    “Little is known about the forces and mechanisms that lead to rift initiation and propagation – partly because we have very few measurements against which hypotheses can be tested.”
    http://geosci.uchicago.edu/research/glaciology_files/iceberg_calving_research.shtml

    “According to a study by scientists at the British Antarctic Survey (BAS) and University College London (UCL) using ESA’s ERS satellite data, a loss of 31-cubic km of ice from the WAIS’s interior from 1992 to 2001 was pinpointed to the Pine Island Glacier.

    The thinning caused the glacier to retreat by over 5 km inland, supporting the argument that small changes at the coast of the Antarctic continent – such as the effects of global warning – may be transmitted rapidly inland leading to an acceleration of sea level rise.

    Although these long-term regional changes are a cause for concern, the present iceberg calving event does not in itself signal a significant change in the WAIS. Over the last 15 years, the glacier front has advanced seawards at a rate of 3 km/year, so the calving of a 20 km-wide iceberg has simply shifted the glacier front back close to where it was after the last calving event in 2001.”
    http://www.sciencedaily.com/releases/2007/10/071019102619.htm

    “Nonclimatic behaviour of calving glaciers has been documented in a large number of locations, both in historical time and during the Late Glacial and Holocene. Interactions between calving dynamics, sedimentation and topographic geometry can partially decouple calving glaciers and marine ice sheets from climate, initiating independent advance/retreat cycles; it is therefore rarely possible to make reliable inferences about climate from their oscillations.”
    http://ppg.sagepub.com/cgi/content/abstract/16/3/253

    Max

    Comment by manacker — 18 Jul 2009 @ 10:30 AM

  310. BobFJ #292: don’t sweat it… I won’t try to teach you anything against your will ;-)

    Comment by Martin Vermeer — 18 Jul 2009 @ 12:45 PM

  311. Typo in that name; hat tip to Google’s suggesting the right spelling; here is some of the research Gavin refers to, for engineering study:

    http://scholar.google.com/scholar?hl=en&q=%22Ian+Joughin%22+ice+crack

    Images (including some at RC you could search — box at the top of the page):
    http://images.google.com/images?hl=en&q=%22Ian%20Joughin%22%20ice%20crack&sa=N&tab=si

    Comment by Hank Roberts — 18 Jul 2009 @ 1:14 PM

  312. CTG

    You wrote: “Whilst the collapse of an ice sheet in itself does not alter the sea level, what it can do is to speed up the flow of the glacier that was feeding it, leading to more ice going into the sea, which will raise the sea level at some point.”

    You are correct (all things being equal). But glacial calving is part of a natural dynamic process. If there is more snow, there will be an increase in glacial mass, resulting from more water leaving the sea, which will lower the sea level at some point. But more glacial mass may again lead to an acceleration of the glacial flow, etc.

    From what I have been able to read, there is no definitive link between global warming and glacial calving in the Antarctic. Maybe you have some links to other data.

    Max

    Comment by manacker — 18 Jul 2009 @ 1:18 PM

  313. From the Wilkins collapse topic earlier, which you can find with the search, I remember posting some tidbits and pointers on the various forces known to affect sea ice, including tides and waves from very distant storms:
    http://www.realclimate.org/index.php/archives/2009/04/wilkins-ice-shelf-collapse/#comment-118731

    Comment by Hank Roberts — 18 Jul 2009 @ 1:22 PM

  314. #308 Jörg Schulze

    I know you have already been answered but I thought I might add for simplicity.

    Making an argument outside of relevant context is, er, um, irrelevant.

    Gavin has properly simplified the argument. It’s not that climate was warmer during the Permian or Eocene optimum, it’s about why it is warmer or cooler.

    To bring in even more relevance, it’s about human infrastructure and needs that have been designed and built around a climate regime that is now changing due to human influence.

    To get a handle on this look at the UCAR/NCAR work:

    http://www.ossfoundation.us/projects/environment/global-warming/natural-variability

    Natural variability on a difference path is a realistic way to characterize the difference.

    Comment by John P. Reisman (OSS Foundation) — 18 Jul 2009 @ 1:27 PM

  315. PS, Max’s third quote isn’t about today’s conditions.

    It can be hard for youngsters now to believe, but until a few years ago, scientists thought Antarctica wasn’t going to start changing quickly.

    This “make a claim, provide some link” trick betrays trust. It’s done often knowing many people don’t actually check the claimed sources. Max can’t be trusted.

    The third link is from 1992.

    Comment by Hank Roberts — 18 Jul 2009 @ 1:34 PM

  316. Oh, kids, double untrustworthy; check the -first- link Max posted against the bit he quoted from it. Read down past the “little is known” (note the date, 2002) to where they say they’re starting research.

    “we’ve been working with an international team of scientists to deploy global positioning system receivers (GPS) and seismometers around the tip of a propagating rift on the Amery Ice Shelf, East Antarctica. The field work has been done in conjunction with a program monitoring rift propagation using satellite imagery.”

    Use those terms to search in Scholar — you can find the results of the research — much more is now known!

    Isn’t science wonderful, if you look it up for yourself?
    Even people trying to fool you can lead you partway toward good information.

    Max can’t be trusted to provide good information.
    Always check.

    Comment by Hank Roberts — 18 Jul 2009 @ 1:39 PM

  317. Fixing a mistake in my comment #289, the constant c in the system response
    k[t - c + transient]
    for a = 1, b = 1/30 and weights both 1/2 is c = 15.5. That’s quite a long delay once the transient has (almost) disappeared.

    Another route to estimate a, b and the weights is to consider Figure 1(a) in the Knutti et al. comment on a paper by Schwartz:
    http://www.iac.ethz.ch/people/knuttir/papers/knutti08jgr.pdf
    to closely reproduce the response to the step function beginning in year 300 of the simulation. (The text suggests three decaying exponentials is more realistic.) Other papers (which I can’t find just now) point out that the initial doubling of CO2 begins to diminish due to ocean uptake, so the forcing is not just the unit stip U(t) but rather U(t)exp(-ht) for some small constant h (as a reasonable approximation).

    Comment by David B. Benson — 18 Jul 2009 @ 2:09 PM

  318. “All this was quite extensively discussed on this site just a couple of months ago, so you obviously have not been paying attention, Max.

    Comment by CTG”

    It’s more that they don’t even notice the response.

    If they read anything, it’s only bits that prove AGW wrong. Even if that means taking them out of context and leaving out important information. Like the date of the quote…

    This could well be because they are being mailed talking points and/or picking them up from others.

    They certainly have enough of the text to make a quote but when you read the source you too easily find where they get it wrong in the same text. If they had actually READ the text then they would not have used it because it’s too easy to counter from it.

    The only thing I can think of is that someone is mailing about to “a few good men” and these rumoured counters to AGW are used indiscriminately.

    Credulously if you like.

    Comment by Mark — 18 Jul 2009 @ 2:27 PM

  319. manacker 18 Jul 2009 at 1:18 pm

    “From what I have been able to read, there is no definitive link between global warming and glacial calving in the Antarctic. Maybe you have some links to other data.”

    Before anybody bothers to look, it would be a good idea to stretch manacker’s personal definition of “definitive” across a board and then pound a nail through each end, thus ensuring you’re not shooting at a moving target. Otherwise I suspect manacker’s “definitive” is going to change length no matter what comes down the pike.

    Manacker, what do you consider to be “definitive” in this case?

    Comment by Doug Bostrom — 18 Jul 2009 @ 2:28 PM

  320. And, lo! picking keywords, trying Google Scholar, just as examples of what’s out there to be read:

    http://scholar.google.com/scholar?hl=en&scoring=r&q=ice+shelf+rift+propagation&as_ylo=2008

    An investigation into the forces that drive ice-shelf rift propagation on the Amery Ice Shelf, …

    JN Bassis, HA Fricker, R Coleman, J Minster – Journal of Glaciology, 2008 – seismo.berkeley.edu

    … and hydro-fracture: Satellite observations and model results of the 2008 Wilkins ice shelf …

    T Scambos, HA Fricker, CC Liu, J Bohlander, … – Earth and Planetary Science Letters, 2009

    … observations of glaciogenic ocean waves (micro-tsunamis) on icebergs and ice shelves

    DR MacAYEAL, A Emile, C Richard, NB … – Journal of Glaciology, 2009 – earth.northwestern.edu

    Seismic observations of sea swell on the floating Ross Ice Shelf, Antarctica

    LM Cathles IV, EA Okal, DR MacAyeal – J. Geophys. Res, 2009 – earth.northwestern.edu
    … rift trending from the southeast toward an actively propagating tip in the northwest (closest to the seismometer site) cuts vertically through the ice shelf …

    West Antarctic Ice Sheet collapse–the fall and rise of a paradigm
    DG Vaughan – Climatic Change, 2008 – Springer
    … of ice sheet into a deep rift beneath its … then the potential for changes to propagate inland …

    Flexural-gravity wave phenomena on ice shelves.
    OV Sergienko, DR MacAyeal, CL Hulbe, R … – American Geophysical Union, Fall Meeting 2008, …, 2008 – agu.org
    … of the ice shelf both influence the wave propagation) throughout the ice … stress distributions around features of interest (eg, ice-shelf rifts, ice rises, etc). …

    You know how to find this stuff. Don’t rely on some guy on a blog to point you to facts. Search for yourself. Ask at your local library for a reference librarian to help you.

    Comment by Hank Roberts — 18 Jul 2009 @ 3:43 PM

  321. Re 318 Mark

    Oh indeed, I am sure they are getting from somewhere. I have been having a debate with someone on another site who also seems to be getting fed “relevant” research. He claimed that the tree-ring divergence problem means that the instrumental record since the 1980s is wrong, and he had a paper that he said proved it. Five minutes on Google Scholar was enough to find a more recent paper by the same authors that found the divergence problem is much less of an issue than previously thought. Odd that he hadn’t taken the time to do the same research himself.

    Comment by CTG — 18 Jul 2009 @ 4:04 PM

  322. Re 312 Max

    “From what I have been able to read, there is no definitive link between global warming and glacial calving in the Antarctic. Maybe you have some links to other data.”

    Um, well perhaps you could start by reading the site that you are commenting on…

    http://www.realclimate.org/index.php/archives/2008/10/what-links-the-retreat-of-jakobshavn-isbrae-wilkins-ice-shelf-and-the-petermann-glacier/

    http://www.realclimate.org/index.php/archives/2006/03/catastrophic-sea-level-rise-more-evidence-from-the-ice-sheets/

    http://www.realclimate.org/index.php/archives/2006/06/ice-sheets-and-sea-level-rise-model-failure-is-the-key-issue/

    After reading those, think about your original claim and see if you still think it is so:

    “Changes in floating sea ice (even including “dramatic” events, such as the collapse of Larsen B and Wilkins) have no substantial impact on sea levels.”

    Comment by CTG — 18 Jul 2009 @ 4:12 PM

  323. Re: Brian Dodge 17 Jul 2009 at #283

    Thank-you for the many citations regarding possible ice thinning.

    I have carefully checked your citations and could find no reference to actual total volumetric ice, anywhere. If you have those figures why didn’t you just state them? I would certainly interested in that data-set.

    Until better data arrives, I will just have to rely on delta area as being proportional to delta volume. Even with depth measurement coming on line, it will be sometime before sufficient data can be historically referenced. The declassification of Navy data may change this situation.

    Comment by G. Karst — 18 Jul 2009 @ 4:20 PM

  324. Co2isnotevil, Reur 286
    You wrote an interesting post which in part said:

    Max, re 282
    Your calculation is incorrect as well. The proper calculation is to first determine the power flux in and out of the surface, which for an average surface temperature of 288K is 390.11 W/m^2 from Stefan-Boltzmann. The forcing power (using the IPCC heuristic) is,
    5.35 * (ln(310/280) – ln(297/280)) = 0.23 W/m^2

    However, and sorry Max for intruding, but could you please explain how your method of calculation using S-B on a complex grey “body” varying in emissivity and temperature, both temporally and spatially, is valid? For instance, when T to the fourth power, relating to HEAT loss from the surface via EMR is contemplated, how do you make a meaningful average of it? Also, don’t forget that there are believed to be greater heat losses from sources other than EMR, e.g. see image from NOAA

    Comment by BobFJ — 18 Jul 2009 @ 5:51 PM

  325. “Solar Cycle Linked To Global Climate”:
    http://www.sciencedaily.com/releases/2009/07/090716113358.htm

    Unusually well-done!

    Comment by David B. Benson — 18 Jul 2009 @ 6:28 PM

  326. Karst found no references to actual sea ice density.
    Here’s an early one (1963). There are many, many more available, follow citations.
    Short answer: it’s quite variable over time; Google Scholar is your friend.

    http://handle.dtic.mil/100.2/AD410182

    “… Average density and salinity values at the different depths for
    each age of ice are shown in Figures 2, 3, 4 and 5. The average
    salinity and density for the total ice thickness of each ice age
    during the summer season are shown in Figure 6. The data from
    which these values were obtained are listed in the Appendix…..”

    Comment by Hank Roberts — 18 Jul 2009 @ 6:30 PM

  327. G. Karst 18 Jul 2009 at 4:20 pm

    “I have carefully checked your citations and could find no reference to actual total volumetric ice, anywhere.”

    From Brian’s first cite:

    “Satellite radar altimeter measurements show that between 1992 and 2001 the Larsen Ice Shelf lowered by up to 0.27 ± 0.11 meters per year.”

    Seems to me it’s no great feat to take the areal coverage of the ice, figure a volume for 1992 based on the shelf height that year, then another volume for 2001 using the reduced observed shelf height.

    That would yield reduced volume, unless the area of the ice has increased sufficiently to account for the loss of height. Was there a commensurate increase in coverage during those years?

    Comment by Doug Bostrom — 18 Jul 2009 @ 6:31 PM

  328. #308
    “You can’t do it for periods that are too short because of the unforced variability”

    Everything changes for a reason, and simply “averaging out” the short periods, then discussing whether or not the trend is statistical or not, is the same as playing Mozart with a Didgeridoo.

    [Response: Does this make any sense to anyone? - gavin]

    Comment by isotopious — 18 Jul 2009 @ 7:21 PM

  329. ALL: Re mechanical hinging failure of ice shelves:
    Thanks for so much interest but I remain unconvinced by the arguments presented that global warming has a significant effect in accelerating the process.

    Hydrostatic pressure as a proposed means of extending mechanically caused cracks sounds nice, but the problem I have with the hypothesis is that I’m not aware of any non-intrusive test that can validate it. Furthermore, ice shelves can be up to around 1,000 metres thick, (of which most is underwater), and this is a huge “thermal mass”. Consequently, the temperature of air within any crack, as distinct from the air above must surely be below freezing, and any melt water can thus not penetrate significantly.

    In a similar fashion it has been shown somewhere, that the bottom layers of (some?) shelves comprise of frozen seawater.

    The hypothesis of massive melt ponds at the surfaceetc, also breaks down when considering the calving of icebergs, which again, is nothing new.
    For instance, icebergs were visible from shore around New Zealand about 100 years ago

    Hank Roberts Reur 320;
    That is an impressive list of titles you refer. How do you find the time to read all that stuff? Going by some of the titles, such as: Seismic observations of sea swell on the floating Ross Ice shelf, I would not have thought to read it WRT the above, but congratulations for finding a connection anyway.
    (Don’t know when I can find time)

    Comment by BobFJ — 18 Jul 2009 @ 7:42 PM

  330. Hasnt China increased particulate emissions significantly since about 1995? Would this explain the recent slight cooling trend?

    Comment by nigel jones — 18 Jul 2009 @ 7:49 PM

  331. “Was there a commensurate increase in coverage during those years?”

    Nope.

    “On average, Antarctic Peninsula (AP) ice shelves have retreated by ~300 km2 each year since 1980 (1). This gradual retreat has been punctuated by two catastrophic collapses, in January 1995 (2) and February 2002, when the remaining northern sections of the Larsen Ice Shelf (LIS) (Fig. 1) fragmented into icebergs. In contrast to the prolonged retreats, these 2000- and 3250-km2 ice-shelf sections—Larsen-A and Larsen-B— disintegrated over days or weeks.”

    Science 31 October 2003: Vol. 302. no. 5646, pp. 856 – 859
    DOI: 10.1126/science.1089768
    Larsen Ice Shelf Has Progressively Thinned
    Andrew Shepherd,1* Duncan Wingham,2 Tony Payne,3 Pedro Skvarca4
    (paywalled; I’m a subscriber)

    Comment by Brian Dodge — 18 Jul 2009 @ 9:38 PM

  332. BobFJ (324), a minor correction: I believe all heat loss from the Earth system is only from radiation; or did I miss what you meant?

    Comment by Rod B — 18 Jul 2009 @ 9:42 PM

  333. I was intrigued by this line from the Swanson paper.

    “The top panel in Figure 1 shows that in a 74 statistically rigorous sense such synchronizations only occurred four times (1910-20; 1938- 75 45; 1956-60; and 1976-1981) during the 20th century, and three of those synchronizations 76 (all but 1956-1960) coincided with shifts in the climate state.”

    Might that suggest a fifth climate mode as yet undetected, that was not synchronized 1956 – 1960? And would it be possible to mathematically deduce a likely periodicity for such a mode using the above information?

    Comment by barry — 18 Jul 2009 @ 10:08 PM

  334. BobFJ 18 Jul 2009 at 7:42 pm:

    “Hydrostatic pressure as a proposed means of extending mechanically caused cracks sounds nice, but the problem I have with the hypothesis is that I’m not aware of any non-intrusive test that can validate it.”

    Sure, and by the same logic we know that destructive testing of all as-built structures is required to validate their design, yes? Materials science does not exist?

    “Furthermore, ice shelves can be up to around 1,000 metres thick, (of which most is underwater), and this is a huge “thermal mass”. Consequently, the temperature of air within any crack, as distinct from the air above must surely be below freezing, and any melt water can thus not penetrate significantly.”

    I believe you intended to say “water within any crack” but your conjecture still does not follow. What about a fracture originating below the ice, in water? Does it adhere to different rules? Does water entering such a fracture automatically freeze? If so, how is it that we observe any fractures either extending either from below or above? Would they not instantly be mended by frozen water?

    Phoning it in.

    Comment by Doug Bostrom — 18 Jul 2009 @ 10:59 PM

  335. Brian Dodge 18 Jul 2009 at 9:38 pm

    “‘Was there a commensurate increase in coverage during those years?’

    Nope.”

    Of course not. “Obtuse” or “recalcitrant”, we do not really know. Not enough data.

    Comment by Doug Bostrom — 18 Jul 2009 @ 11:02 PM

  336. Rod B Reur 332,
    Sorry, I was talking about heat loss from THE SURFACE, the largest portion being via evapo-transpiration. The NOAA figure that I linked to shows it rather well

    Comment by BobFJ — 18 Jul 2009 @ 11:05 PM

  337. Martin Vermeer, you wrote in your 310:

    BobFJ #292: don’t sweat it… I won’t try to teach you anything against your will ;-)

    Now that has me more than puzzled. For example, are you suggesting that the SOHO MDI image of the sun of quality 151 KB, (or you can click for a 657 KB enhancement), is inferior to the 9.65 KB “depiction” in Wiki’, and that it does not show a difference?

    Comment by BobFJ — 18 Jul 2009 @ 11:19 PM

  338. Until better data arrives, I will just have to rely on delta area as being proportional to delta volume.

    First year ice thickness vs. older ice thickness is known (on average). We know that much more of the arctic winter extent is now first year ice. Therefore, the volume’s different.

    Your reliance isn’t based on logic or known data, but your political ideology. Pseudoscience, in other words.

    Comment by dhogaza — 18 Jul 2009 @ 11:43 PM

  339. > remain unconvinced
    Uh huh. And so you use logic instead of reading research.
    How many teeth does a horse have? Famous question.

    > How do you find the time
    Start young, persist for decades, and rely on librarians.
    Stay curious about everything, and never rely on logic or memory.
    Look things up, each time.

    If you can’t read the research, at least read the summaries. Paste the name of the paper into Scholar to find other papers citing it.

    Here, this is engineering material. Just a little snippet; and this is just one of many papers on various issues being looked at about what’s happening.

    Why rely on logic when the science is so rich and so available?
    Wonder how many teeth a horse has? go ’round to the stable.

    Transoceanic wave propagation links iceberg calving margins of
    Antarctica with storms in tropics and Northern Hemisphere
    GEOPHYSICAL RESEARCH LETTERS, VOL. 33, L17502, doi:10.1029/2006GL027235, 2006

    “… Sea Swell: An Agent in Iceberg Calving and
    Break-Up?

    [8] Considering the long history of investigation into
    trans-oceanic propagation of long-period ocean waves
    [Munk et al., 1963; Snodgrass et al., 1966], it is not
    surprising that our observations have revealed examples of
    sea swell traveling half-way around the earth to shake
    icebergs and ice shelves along a broad swath of the
    Antarctic coastline. What is unique about the observations
    presented here is that they imply that giant icebergs and the
    calving margins of major ice shelves are mechanically
    influenced by meteorological conditions in the far field.
    Considering that iceberg calving is involved in the mainte-
    nance of Antarctica’s ice-mass budget [Jacobs et al., 1992],
    it is thus natural to consider whether climate conditions in
    the extra-tropical northern hemisphere and the tropics (e.g.,
    storm intensity or hurricane/typhoon frequency) could exert
    a control on the mass budget of the Antarctic Ice Sheet.
    [9] A leading hypothesis for how tabular icebergs are
    calved concerns swell-induced vibration that can fatigue
    and fracture ice at weak spots, producing rifts that become
    iceberg-detachment boundaries [Holdsworth and Glynn,
    1978; Kristensen et al., 1982; Zwally et al., 2002]. With
    this hypothesis in mind, we considered whether the arrival
    of swell from the Gulf of Alaska storm discussed above
    contributed to the spectacular break-up of B15A on October
    27 2005 (Figure 1a)….”

    http://www.earth.northwestern.edu/people/emile/PDF/EAO186.pdf

    Comment by Hank Roberts — 18 Jul 2009 @ 11:48 PM

  340. #305 Barton Paul Levenson,

    There is no such requirement for a 30 year time scale for temperature statistics. What you are referring to is an arbitrary time scale chosen by the WMO for a climate signal to emerge from noise. This has nothing to do with temperature analysis which can be done at shorter time scales as has often been done by scientists at this site as well as Tamino.

    I say it is an arbitrary figure because I have asked time and again for an empirical justification or a peer reviewed publication justifying this time scale and have been met with either stony silence or, in the case of one person, an improper and wrong comparison to the acceptance of the celsius scale as a standard in science.

    Comment by Richard Steckis — 19 Jul 2009 @ 1:25 AM

  341. #328 Isotopius then Gavin says:

    “Everything changes for a reason, and simply “averaging out” the short periods, then discussing whether or not the trend is statistical or not, is the same as playing Mozart with a Didgeridoo.

    [Response: Does this make any sense to anyone? - gavin]”

    As an Australian, I can identify with the statement quite easily. It is in fact a good analogy although it may be wrong in this context.

    Comment by Richard Steckis — 19 Jul 2009 @ 1:36 AM

  342. “Consequently, the temperature of air within any crack, as distinct from the air above must surely be below freezing, and any melt water can thus not penetrate significantly.”

    Consider the temperature a gram of ice would have to be below zero to freeze a gram of water. Also, consider the rate at which the heat would diffuse through the surrounding ice if water was poured into a crack. And then, consider the forces generated by the expansion of the water in a crack as it froze. Ponding of liquid water was observed on the surface of Larsen B prior to collapse, and liquid water can penetrate cracks & crevasses in ice sheets and shelves, otherwise moulins wouldn’t exist. Cracks are initiated by various stresses- tides, winds, flow gradients – and no doubt there are complex interactions of the various forces involved. For instance, as the ice warms from the energy transported into cracks by liquid and freezing water, its strength will decrease, and thermal expansion will create localized stresses. These new stresses will interact with tidal stress, and the changing stresses will cause strain and creep, which will in turn cause effects like crack propagation, new crack formation, and dimension changes in existing cracks that will pump water (and heat) around. A geophone(paggophone?) recording of an ice shelf collapse would probably sound very interesting.

    Comment by Brian Dodge — 19 Jul 2009 @ 1:59 AM

  343. #305 Barton Paul Levenson says:

    “It’s like me taking the temperature here at one-minute intervals from 6 AM to 9 AM. That gives me 181 points, which I then use to show a significant upward trend in temperature, proving that the oceans will boil in two days.”

    I astounds me how some people can argue that the more data points one has, the less reliable is the statistical analysis. The fact is the data points encompass nearly a decade not a single year. Your appeal to ridicule in you example is well…. Ridiculous.

    Comment by Richard Steckis — 19 Jul 2009 @ 3:08 AM

  344. [Response: Does this make any sense to anyone? - gavin]

    Yes, iso is confused because you aren’t saying he’s right (and he KNOWS he is, so anything that isn’t saying so must be wrong), so he wants to spread it about.

    After all, confusion shared is confusion doubled.

    Comment by Mark — 19 Jul 2009 @ 3:19 AM

  345. “Hydrostatic pressure as a proposed means of extending mechanically caused cracks sounds nice, but the problem I have with the hypothesis is that I’m not aware of any non-intrusive test that can validate it. ”

    Then you have a problem with intrusive testing too?

    Do you have a proposition that this would NOT happen?

    After all, aero engineers knew that the bumble bee couldn’t fly, but it didn’t do the maths and flew anyway. Then after some long time, the invention of sophisticated equipment meant taht the reason for it could be tested.

    It seems like bumble bees CAN fly.

    Now your complaint sounds a lot like “where’s the empirical evidence for it” seen so often in denial circles. Apparently it doesn’t work if you test a theory in isolation so you can control the variables and factor them out because it isn’t a trillion-ton block of ice on a remote island…

    Comment by Mark — 19 Jul 2009 @ 3:23 AM

  346. BobFJ: “(Don’t know when I can find time)”

    Still you find time for posting…

    Comment by Martin Vermeer — 19 Jul 2009 @ 3:52 AM

  347. “Response: Does this make any sense to anyone? – gavin”

    It makes sense to me, should I be scared? He is simply saying there is no true noise in the system since there are physical reasons behind any such noise. I doubt the importance of being able to identify the source of the noise in each and every instance but that is his point from how I read it.

    Comment by stevec — 19 Jul 2009 @ 6:02 AM

  348. BobFJ
    18 Jul 2009 at 7:42 pm

    Consequently, the temperature of air within any crack, as distinct from the air above must surely be below freezing, and any melt water can thus not penetrate significantly.

    What do you mean by this? That any water flowing into a crack will immedately freeze and consequently not penetrate very deep? Do you have any observations to confirm this?

    The hypothesis of massive melt ponds at the surfaceetc, also breaks down when considering the calving of icebergs, which again, is nothing new.

    Can you please explain how exactly the ‘melt pond hypothesis’ breaks down? This remark leaves a bit too much to my imagination. You’re essentially asking me to take your word for it.

    Comment by Anne van der Bom — 19 Jul 2009 @ 7:20 AM

  349. Chris @ 17 Jul 2009 at 9:18 am:

    I believe I have found the answer to my original question myself; I had misread the graph! The graph is too fine on my screen and it looked like an ’1850′ at the bottom left. However I have now seen the same graph reproduced at James Annan’s blog, larger, and I realised that it begins at 1950. Thus it appears to me that Dr. Swanson meant, the true trend one beginning 1950, not 1850. That’s good; it takes us further from the LIA. I don’t need to mention that there doesn’t seem to be any warming at all in IPCC2007 SPM Fig. 1. My apologies for the misunderstanding. Puzzling that no one corrected me! :)

    Comment by Alex Harvey — 19 Jul 2009 @ 7:47 AM

  350. CTG

    Thanks for your 322 with RC references on ice sheets, glacial calving etc.

    These were very interesting (I had actually read one of the three previously).

    That marine outlet glaciers detach from their beds and then start floating and calving seems like a normal process, as is the inland snowfall that provides the ice mass of the glaciers in the first place. Since glaciers are simply rivers of frozen water this is obviously very much an ongoing dynamic process.

    The mountain glaciers in Switzerland (where I live) have been retreating since around 1850, when they apparently reached their greatest extent of the past 10,000 years. As they retreat today, signs of earlier civilizations and vegetation during warmer periods (MWP, Roman Optimum, for example) are often found, indicating that these glaciers react to global temperature swings, periods of reduced local winter snowfall, etc.

    The example is given of the Petermann Glacier (Greenland), a large portion of which is already afloat and apparently calves 60 km^3 per year of ice.

    Paleoclimate studies show that sea levels were 3-4 m higher when the AIS was much smaller than today. Speculations of future sea level rise (perhaps some unspecified day in the future maybe) are interesting but hardly conclusive.

    The studies on the GIS and AIS are also interesting. While not mentioned in the RC write-ups, both GIS and AIS were shown to have grown in relatively long-term studies from 1992 to 2003 (Zwally/Johannessen and Wingham), but the GIS appears to be shrinking today based on more recent shorter-term studies.

    All-in-all your references did not provide any conclusive evidence that there is a definitive link between global warming and glacial calving today. It also did not convince me that this process (even major events such as Wilkins or Larson B) is contributing significantly to sea level rise today.

    But thanks for some interesting links, anyway.

    Max

    Comment by manacker — 19 Jul 2009 @ 9:09 AM

  351. Gavin

    You asked (328) if isotopious’ remark below (308) makes sense to anyone:
    :
    “Everything changes for a reason, and simply “averaging out” the short periods, then discussing whether or not the trend is statistical or not, is the same as playing Mozart with a Didgeridoo.”

    (This was In response to your statement on 308 regarding short-term versus longer-term trends that cannot be compared: “you can’t do it for periods that are too short because of the unforced variability”).

    Yes, Gavin, isotopious’ remark does make sense.

    First of all, you have to be aware of the limitations of the “Didgeridoo” as a musical instrument (few outside Australia are). If you “average” out Mozart’s “Eine kleine Nachtmusik” sufficiently, you will eventually have a monotonal sound playable on a “Didgeridoo”, but it will no longer be “Eine kleine Nachtmusik”.

    The short-term trends are being “averaged out” (or ignored) because they cannot be attributed to the assumed long-term climate forcing according to the theory but rather to “unforced variability” (which is not covered by the theory and has therefore not been assumed). It is sort of like modifying the observed physical data to match the assumed theory.

    Isotopious’ point that “everything changes for a reason” is valid, even if this reason is “unforced variability”, which has not been assumed by the theory.

    It could well be that unexplained forcing factors and “unforced variability” are actually driving our climate as much as or to an event greater extent than the forcing from the assumed theory, right? I have seen no conclusive empirical evidence to the contrary, so isotopious’ remark stands unless someone can bring this evidence.

    Max

    Comment by manacker — 19 Jul 2009 @ 9:47 AM

  352. Hank Roberts 18 Jul 2009 at #326 “McMurdo Sound”
    Doug Bostrom 18 Jul 2009 at #327 “Larsen Ice Shelf”

    I assume you both have a scientific background, so I assume you both understand the scientific concept of representative sampling. So I find it somewhat curious that you cite isolated studies of small areas in the western Antarctic as being representative of total global ice mass (or even antarctic ice mass).

    I am confident that reliable, trend(able), data will be available for analysis before too long. Then we will all be standing on firmer ground. Try preventing decent into mind-sets until then. All is not known and the future is coming at us at 3600 sec per hour, under foggy visibility.

    Thanks for the conversation and interesting cites.

    Comment by G. Karst — 19 Jul 2009 @ 10:02 AM

  353. CTG

    Back quickly to the LarsenB and Wilkins events.

    These were already floating, so the breakup had no impact on sea level, as discussed earlier.

    But let’s assume they had been grounded before breaking up (the ice was most likely once grounded ice before it became part of a floating ice shelf).

    LarsenB had 3,250 km^2 of ice and Wilkins around 2,000. Assuming they were both 200 meters thick, this would be a total of 1,050 km^3 of ice, which would cause sea level to rise by 2.9 millimeters.

    Estimated average annual snowfall in Antarctica is 5 cm (water equivalent), which equals 700 km^3 of water removed from the ocean or the equivalent of lowering sea level by 1.9 millimeters per year.

    Some studies postulate that snowfall would increase in a warmer Antarctica, so that this number would increase. But who knows in actual fact?

    It is obviously a dynamic situation.

    Max

    Comment by manacker — 19 Jul 2009 @ 11:00 AM

  354. re #301.

    manacker

    I think we agree that your original assertions in post #266 are incorrect. There was substantial “human CO2″ and this almost certainly did make a substantial contribution to warming not just during the period 1910-1944 (as your own calculation indicates) but to the entire period from the start of the 19th century..

    Let’s look more closely at your new wriggle on this: You point out that the Hadley Centre Hadcrut analysis gives an extreme range of warming of 0.54 oC between 1910 and 1944. This is a highly cherrypicked time range (nice!) – and you like co2isnotevil’s suggestion that this warming could be due to sunspot numbers.

    Let’s have a look.

    The period from the early 1880′s to around 1910 in the Hadcrut analysis shows substantial cooling. This is likely the temperature response to the substantial negative forcings from volcanic aerosols arising from a particularly active period of volcanism (Galunggung, 1882, Krakatau, 1883, Colima 1890, Thompson Island 1896, Soufrieret 1902, Santa Maria 1902, Mount Pelee, 1902). This contributed to a reduction in temperature anomaly from around -0.3 around 1880 to around -0.5 around 1910.

    So we expect a significant contribution from temperature recovery following wash out of atmospheric aerosols and relief from this negative volcanic forcing in the post 1910 warming. What we really need to explain is the warming of perhaps 0.25 – 0.3 oC left over.

    We’ve already agreed that there was likely a substantial contribution from anthropogenic CO2 (your “human CO2″). That’s inescapable, since there’s no question that atmospheric CO2 concentrations increases substantially in the periods during and leading up to yout time range. co2isnotevil suggests a sunspot related effect. That’s an odd one since here was nothing particularly anomalous about the sunspots during this period:

    http://en.wikipedia.org/wiki/File:Sunspot_Numbers.png

    and recent estimates of solar contributions [*] to early 20th century warming gives us perhaps a contribution of 0.1 oC for your 1910-1944 period.

    So the likely contributions to early 20th century warming in the period you specify are something like 0.2- 0.25 oC of recovery from negative volcanic forcing, 0.1-0.2 oC of anthropogenic greenhouse forcing, and around 0.1 oC of solar forcing. One shouldn’t make the mistake of assuming that there is only one contribution to any period of temperature variation!

    [*] Lean JL, Rind DH (2008) How natural and anthropogenic influences alter global and regional surface temperatures: 1889 to 2006 Geophys. Res. Lett. 35 art # L18701

    http://www.agu.org/pubs/crossref/2008/2008GL034864.shtml

    Comment by chris — 19 Jul 2009 @ 11:47 AM

  355. re #349

    O.K. Alex! I did wonder what you meant when you referred to Swanson and Tsonis’s theory of an underlying true forced warming signal from GHG emissions that began in 1850 and continues today. I hunted through their paper for evidence of that and assumed that you had read it elsewhere.

    That’s why I referred to “your interpretation of Swanson and Tsonis theory…”

    Nevertheless, there was likely a significant human contribution to warming from at least 1850 as the atmospheric greenhouse gas levels indicate.

    Comment by chris — 19 Jul 2009 @ 11:57 AM

  356. And that, folks is why the Hadley Centre doesn’t include Artic measures.

    People like G.Karst will use it to say “you have this minor thing maybe wrong, so therefore your whole thing must be wrong…”

    Comment by Mark — 19 Jul 2009 @ 12:38 PM

  357. “Can you please explain how exactly the ‘melt pond hypothesis’ breaks down?

    Comment by Anne van der Bom”

    Think Jim Carey: “It’s devastating to my case!”.

    He isn’t wrong, therefore anything that could prove it must itself be wrong.

    Comment by Mark — 19 Jul 2009 @ 12:39 PM

  358. manacker 19 Jul 2009 at 9:47 am

    “It could well be that unexplained forcing factors and “unforced variability” are actually driving our climate as much as or to an event greater extent than the forcing from the assumed theory, right? I have seen no conclusive empirical evidence to the contrary, so isotopious’ remark stands unless someone can bring this evidence.”

    Your standards are so elastic.

    On the one hand, we have an enormous body of scientific research with demonstrated though imperfect predictive capacity as well as an imperfect yet growing body of empirical data, both of which appear to be lending increasing confidence to the scientific foundations of climate research.

    For you this is insufficient to the point of ridicule. And please, don’t say you have not found it ridiculous or we’ll all have to be treated to more manacker quotes, empirical evidence as it were.

    As a response, you offer “unexplained forcing factors” as offering so massive a potential impact as to entirely counteract and contradict the sizable and growing body of research, theory and evidence explaining the behavior of our climate.

    Your hypothesis is so vague as to appear as superstition, particularly the blind faith you invest in its power.

    You then make the remarkable demand that somebody else provide empirical data to contradict your hypothesis, an impossible request as you have provided nothing to test, just vague mumbo-jumbo about “unexplained forcing factors”.

    Not only elastic, but lazy. Surely you can do better.

    Comment by Doug Bostrom — 19 Jul 2009 @ 12:51 PM

  359. G. Karst 19 Jul 2009 at 10:02 am

    As you have not shown otherwise, I take it then that you concede the Larsen ice shelf lost a significant amount of volume during the period 1992-2001? We can add that to the body of “reliable, trend(able)” data?

    If you do not make that concession, can you show why not, using data?

    Comment by Doug Bostrom — 19 Jul 2009 @ 1:01 PM

  360. The tidal data from the San Francisco gauge shows a markedly similar pattern. The long run slope (year < 1997) is .0083 feet per year (p<0.0001). The slope between 1997 and 2009 is -0.0028 feet per year (p=.678). So clearly sea level rise has stalled as well. Which, according to the gauge data, it has 9 times since 1900. This clearly shows that global warming follows a punctuated equilibrium after periods of great change. Global climate change by jerks if you will.

    For those who like the pictures with colored least squares lines can see them at: http://www.neilpelkey.net/UnrealClimate.pdf
    For those who must play with the data themselves.
    http://www.neilpelkey.net/tides.xlsx

    P.S. please do not bother arguing that my statistical models or choice of data are probably suspect. That is, after all, my point.

    Comment by Neil Pelkey — 19 Jul 2009 @ 1:18 PM

  361. So about the relaxation trajectory: is it fair to view the climate system’s response to the anthropogenic perturbation as a superposition of a steady-state response and a transient response?

    Viewed this way, the Swanson and Tsonis paper is characterizing the transient response. The transient response can delay the arrival of the steady-state response, but the system must eventually achieve its equilibrium state. This is how I’ve been interpreting Karl’s conclusion: What do our results have to do with Global Warming, i.e., the century-scale response to greenhouse gas emissions? VERY LITTLE

    Comment by Jim Galasyn — 19 Jul 2009 @ 2:03 PM

  362. BobFJ #337,

    did you mean these SOHO MDI images?

    http://soi.stanford.edu/production/int_dk_gifs.html

    (Yeah, you have to be careful with digital imagery, the Kremlin never sleeps :-) )

    Comment by Martin Vermeer — 19 Jul 2009 @ 2:55 PM

  363. Karst is just having fun attracting attention.
    He says there’s no data.
    I point to how to find it.
    I give an example from decades ago, from which he could work forward to find all the subsequent research citing that paper.
    He complains that paper is not “representative of total global ice mass.”

    Clue: People will make an effort _for_a_while_ to help, on the chance you’re very young, or very new to the subject, or don’t know how to look things up.

    After that you’re just setting up strawmen in the road in hopes to get more attention by suckering someone into attacking your dummies.

    Why bother.

    Comment by Hank Roberts — 19 Jul 2009 @ 2:56 PM

  364. Re 350 Max

    Somehow I just knew the words “conclusive” and “definitive” would appear in your rebuttal. Weasel words that allow you to pretend that this problem does not exist.

    I haven’t seen you present any evidence – conclusive, definitive or otherwise – that melting of ice sheets does not influence sea levels. Any yet you quite categorically stated that ice sheet have “no substantial impact”.

    I presented several reviews, which in turn referenced several published papers that show quite strong evidence that there is an impact, but you dismiss this out of hand. So where does this authoritative stand come from? Are you God? Or have you read some science that the rest of us have missed?

    Or are you just mindlessly regurgitating what the oil industry wants you to believe?

    Comment by CTG — 19 Jul 2009 @ 3:37 PM

  365. ” Surely you can do better.

    Comment by Doug Bostrom ”

    That would require work, though.

    He’s paid by the word, not by the fact, you know…

    Comment by Mark — 19 Jul 2009 @ 4:01 PM

  366. Climate. 1. The meteorological conditions, including temperature, precipitation, and wind, that characteristically prevail in a particular region.
    from
    http://www.answers.com/topic/climate

    Web definition: the weather in some location averaged over some long period of time
    from
    http://www.google.com/search?hl=en&client=firefox-a&rls=org.mozilla:en-US:official&hs=nTz&defl=en&q=define:climate&ei=SpdjSsf3MI6asgOdxqBn&sa=X&oi=glossary_definition&ct=title

    WMO specifies 30 years or longer.

    Comment by David B. Benson — 19 Jul 2009 @ 5:05 PM

  367. Cool:

    Solar Cycle Linked To Global Climate

    Establishing a key link between the solar cycle and global climate, research led by scientists at the National Science Foundation (NSF)-funded National Center for Atmospheric Research (NCAR) in Boulder, Colo., shows that maximum solar activity and its aftermath have impacts on Earth that resemble La Nina and El Nino events in the tropical Pacific Ocean.

    The research may pave the way toward predictions of temperature and precipitation patterns at certain times during the approximately 11-year solar cycle.

    “These results are striking in that they point to a scientifically feasible series of events that link the 11-year solar cycle with ENSO, the tropical Pacific phenomenon that so strongly influences climate variability around the world,” says Jay Fein, program director in NSF’s Division of Atmospheric Sciences. “The next step is to confirm or dispute these intriguing model results with observational data analyses and targeted new observations.”

    Comment by Jim Galasyn — 19 Jul 2009 @ 5:59 PM

  368. Hank Roberts Reur 339:

    Yes, I remain unconvinced that there is any climatic effect that significantly accelerates the mechanical hinging failure of ice shelves and the calving of icebergs. (ongoing for millions of years) As I’ve stated, the influence of melt water penetrating the cracks may be intuitively significant, but on closer inspection it is doubtful, because of the huge “thermal mass” that should rapidly freeze any water entering the cracks

    You quoted and linked to a GRL paper entitled “… Sea Swell: An Agent in Iceberg Calving and
    Break-Up?

    Yes, I agree, there are mechanical effects that result in fracturing of the ice and two prime ones are tidal, and wave action. Your reference does NOT discuss the issues on which I’m unconvinced by any of the arguments raised here.

    Please refer to the following image of the Ross ice shelf, and you may notice that it terminates abruptly from mechanical shearing
    http://www.eoearth.org/upload/thumb/1/10/Ross_edge_large.gif/250px-Ross_edge_large.gif
    It is interesting to compare with the white Cliffs of Dover….. Got it?
    http://upload.wikimedia.org/wikipedia/commons/thumb/7/7e/White_cliffs_of_dover_09_2004.jpg/350px-

    You may also find the three papers linked to in Max’s 309 interesting
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    Max, Reur 309:(/b>
    Thanks for the links…. Interesting stuff!
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    Doug Bostrom 334, Anne van der Bom 348:
    Maybe the above helps?
    Anne; I remain unaware of anything empirically quantifying the hypothesis of hydrostatic cracking, and believe that it is all intuitive chat. Neither have I seen anything to confirm my belief that liquid water cannot exist within the huge “Thermal mass” of ice shelves, that are anywhere between around 100 and 1,000 metres* thick. However, as an engineer, it remains to me, a very strong intuitive argument.
    * about 330 to 3,300 feet thick

    Comment by BobFJ — 19 Jul 2009 @ 6:06 PM

  369. Martin Vermeer Reur 346, Do you remember my 337, where I was rather puzzled by what you had written earlier, and I responded as follows:

    Now that has me more than puzzled. For example, are you suggesting that the SOHO MDI image of the sun of quality 151 KB, (or you can click for a 657 KB enhancement), is inferior to the 9.65 KB “depiction” in Wiki’, and that it does not show a difference?

    Your latest post is also unhelpful, and you continue to evade answering a simple question.

    Comment by BobFJ — 19 Jul 2009 @ 6:58 PM

  370. Richard Steckis says: There is no such requirement for a 30 year time scale for temperature statistics. What you are referring to is an arbitrary time scale chosen by the WMO for a climate signal to emerge from noise.

    For a nice description of why you need 30 years of data to infer a climate trend, see
    Results on deciding trends.

    Comment by Jim Galasyn — 19 Jul 2009 @ 7:19 PM

  371. With the apparent ongoing forcing of about 0.15C/decade is it not likely that the ‘pause’ in observed surface temperature rise is occasioned by an increase in the effectiveness of available thermal sinks?

    We have increased wind velocity in the southern ocean, which will be exposing deeper and colder waters to the air, and hence increasing the depth of that sink at the expense of warming deeper waters.

    We have increased fracturing and breakup of floating ice – with the smaller cakes presenting a higher surface area per mass of ice. This gives faster melt, and so faster uptake of heat from surface atmosphere.

    We have increased fracturing of ice cap and ice sheet/shelf surfaces which increases the surface area exposed to the atmosphere.

    We have increased intrusion of near-surface water into grounded ice masses including under West Antarctic, which also drops the local temperature as the ice melts.

    All these sinks have finite capacity before they get to equilibrium. It is not unexpected that the water-ice mixture remains close to freezing until the last bit of ice is melted, nor will it be a surprise when warming recommences with a hiss and a roar when these sinks approach equilibrium with surface air temperatures.

    Any ‘pause’ in the observed pattern of temperature rise is just a case of the monster gathering itself before it springs from its lair again, with renewed vigour!

    Comment by Nigel Williams — 19 Jul 2009 @ 8:24 PM

  372. Jim Galasyn (361) — Yes, it is most reasonale to view the response to a pertubation as consisting of a superposition of a steady-state response and a transient response. So your concluding paragraph is indeed correct.

    Comment by David B. Benson — 19 Jul 2009 @ 8:40 PM

  373. BobFJ says: 19 Jul 2009 at 6:06 pm

    “I remain unconvinced that there is any climatic effect that significantly accelerates the mechanical hinging failure of ice shelves and the calving of icebergs.”

    That’s quite a leap. Let’s just leave aside concentration of hydrostatic forces acting on a crack apex (a crack and its apex is an engineer’s nightmare) for a moment and instead think of an ice sheet in beam terms. We can make a beam of ice and test it, or we can predict what might happen to already existing beams. No controversy there, right?

    As the cross section of a beam is reduced, with all other factors remaining equal its resistance to bending decreases, yes?

    The material properties of ice can be used to predict the competence of a beam made of ice, yes?

    Ice is not made of magical materials so a beam made of ice of 1X thickness will be less resistant to bending and ultimate failure than a beam of 2X thickness, yes?

    In the case of ice shelves where thickness has been reduced, we can thus expect an earlier onset of failure in response to a given deflecting force, yes?

    By “climatic effect” we include warmer temperatures, including sea temperatures, yes?

    In general we’d expect an ice shelf fed at a constant rate and afloat in warmer water to retain less mass at any given point compared to if it were fed at the same rate and afloat in cooler water, yes?

    In losing mass we’d expect that ice shelf to become less thick, meaning less beam cross section, yes?

    We’ve already established that ice is not magic and that a beam of ice becomes less competent against bending loads as it loses cross section, yes?

    When a beam is deflected to levels causing excessive strain it may yield either plastically or by brittle failure, yes?

    We see by existing examples that ice shelves apparently are in fact not very plastic and tend to yield in brittle failure, a process called “calving”, yes?

    I find it genuinely astounding that you can find your way to a conclusion that the mechanical strength of ice shelves is immune to climate effects.

    Cracks of any depth just make the outcome worse. I don’t know the material properties of ice well enough to say with complete confidence that it is incapable of complete structural healing via refreezing, but all the same that is so unusual a property that it would be surprising if true.

    Meanwhile, your remarks on refreezing are hand-waving. You’re trying to contradict without doing any work. Saying “but on closer inspection it is doubtful, because of the huge “thermal mass” that should rapidly freeze any water entering the cracks” is not doing the work needed to support your hypothesis.

    Comment by Doug Bostrom — 19 Jul 2009 @ 8:48 PM

  374. Martin Vermeer 362:
    Please look again at my 191 to which I referred you.
    The link therein is: http://sohowww.nascom.nasa.gov/data/realtime/mdi_igr/512/

    Why do you yet again evade the very simple question in my 337, by making more obtuse statements such as asking if I meant some other link, when all you had to do is click on the link that I gave to see that it IS SOHO MDI?

    Here is my question 337 again:
    “For example, are you suggesting that the SOHO MDI image of the sun of quality 151 KB, (or you can click for a 657 KB enhancement), is inferior to the 9.65 KB “depiction” in Wiki’, and that it does not show a difference?

    Please answer the question.

    Comment by BobFJ — 19 Jul 2009 @ 10:14 PM

  375. Bob, you ‘remain unconvinced’ because nobody’s trying to convince you.
    Your understanding is about where the field was ten years ago, before all the recent research came in. That raised a great many questions that the researchers are describing and working on in a veritable flood of publications.
    And the International Polar Year research is only now beginning to work its way through the journal process, so there’s far more to come.

    All anyone’s trying to convince you to do is read the literature and remain interested in a field that’s fascinating to those who, well, like this kind of thing. Even people like me who cheer from the sidelines.

    So if your point is that you’re not convinced, you could start a blog and explain to the world what it is you’re not convinced about, and maybe interest people in trying to convince you. But you won’t get satisfaction here doing it.
    http://scholar.google.com/scholar?q=ice+shelf+fracture

    Why not be interested instead? Join the uncertain folks who’re reading what the scientists are doing. It’s better than most other forms of entertainment.

    Comment by Hank Roberts — 19 Jul 2009 @ 10:45 PM

  376. Brian Dodge, Reur 342:
    Thank you for your carefully considered and very detailed comments.
    They deserve a carefully considered response from me.
    However, I can only address quickies at the moment, but I’d like you to know that I’m not ignoring it, and I‘ll get back to you later.
    For one thing, I’m distracted by “The Ashes” cricket series at Lords, (England versus Australia) game 2, with day 5 dawning.

    Comment by BobFJ — 20 Jul 2009 @ 12:00 AM

  377. #370 Jim Galasyn,

    Thanks Jim. That is the closest anyone has come to scientifically justifying the 30 year period. I will look at it more closely. However, I do not know if it can be reconciled with short term perturbations that can have long term consequences.

    As I described above (#156), I identified three putative breakpoints in the HadCRUt3 data from 1950 through to present. Each one may compound on the one before to produce the overall warming of that 59 year period. Therefore just looking at the long term dataset without determining shorter time scale influences can give an incorrect picture about overall climate change and its causes.

    Comment by Richard Steckis — 20 Jul 2009 @ 12:10 AM

  378. @ Hank Roberts 19 Jul 2009 at 2:56 pm “Why bother?” Well, I’m retired, widowed, childless, have a relatively high speed internet connection, and haven’t got a lot of other stuff to draw my interest. Eventually the deniers will give up and go away(I’m not under any illusion that I will change their minds) and I will have learned a little more about climatology, and have had the opportunity to make fun of the willfully ignorant with an occasional snarky comment.

    @ manacker
    “It could well be that unexplained forcing factors and “unforced variability” are actually driving our climate as much as or to an event greater extent than the forcing from the assumed theory, right? I have seen no conclusive empirical evidence to the contrary….”
    So, you conclude that the absence of evidence that “unexplained” (invisible, magical?) factors aren’t there is evidence that they “could well be”? Absent conclusive empirical evidence, it could well be that pigs can fly and Hades has frozen over. Or, to put in in more familiar terms, absence of evidence is not evidence of absence.

    @ G. Karst
    “So I find it somewhat curious that you cite isolated studies of small areas in the western Antarctic as being representative of total global ice mass (or even antarctic ice mass).”
    The small areas of Larsen A&B plus Wilkins that collapsed, because of their 200+ meter thickness, more than offset the growth in thin seasonal sea ice. You can’t just compare 7000+ km^2 of lost shelves with growth of 400,000 km^2 of sea ice.
    Larsen A – 2000km^2
    larsen B – 3250km^2
    Wilkins – 2000km^2
    total area 7250km^2=7.25e^9m^2 Thickness 200+ meters
    Larsen + Wilkins lost volume 7.25e9*2e2=14.5e11m^3
    Pine Island sector lost volume 114km^3=1.14e11m^3 [1] (per year,2005) or 3.42e11m^3 through 2008
    Antarctic peninsula east coast 34km^3= 0.34e11m^3 [2] (per year,2005) 0r 1.02e11m^3 through 2008
    grand total (14.5+3.42+1.02)e11m^3=1.89e12m^3 lost
    sea ice gained (400,000 km^2 at 2 meter thickness, gained over 30 years; G. Karst, 17 Jul at 9:18 am)
    4e5*1e6*2=8e11m^3/30 years or 2.67e10m^3 per year
    18,9e11/8e11=2.36 times as much lost (not counting the 30 year sea ice gain to the various other time frames ratio. I’m doing the math in my head – if anyone wants to get picky, I’ll happily fire up a spreadsheet. The simplifications I’ve made are in favor of the hypothesis that sea ice gain of 400,000 km^2 gives “Remarkably stable total ice (volume) results.”, and it still loses)

    from http://rsta.royalsocietypublishing.org/content/364/1844/1637.full This paper has about 70 references, many with links, some freely downloadable; the areas currently under scientific study are neither small nor isolated.

    “The Pine Island Bay sector of West Antarctica exhibits the largest negative mass balance of all Antarctica.”
    “The glaciers draining West Antarctica into Ronne Ice Shelf are close to a state of mass balance.”
    “The glaciers draining into Ross Ice Shelf exhibit a positive mass budget ”
    “The positive ice balance of Siple Coast is more than three times smaller than the negative ice balance of Pine Island Bay, so that overall West Antarctica is losing mass (Rignot & Thomas 2002).”
    [1.]“In total, the mass loss from the Pine Island sector increased from 81±17km3/yr ice in 1996 to 114±18km3/yr ice in 2005.”

    “In East Antarctica, most glaciers are closer to a state of mass balance than assumed in the past, but there are exceptions. ”
    “Totten Glacier and Moscow University Ice Shelf are thinning rapidly, along with most glaciers in Wilkes Land, such as Mertz, Ninnis and Frost.”
    “Several glaciers (e.g. Lambert, David, Shirase) await more precise grounding line thicknesses and mean accumulation values to improve confidence in the mass budget results.”
    “Overall, with the available data and uncertainties in mean accumulation and thickness, it is difficult to determine even the sign of mass balance of East Antarctica.”

    “The Antarctic Peninsula has experienced regional warming six times the global average over the last century (Vaughan et al. 2001). ”
    “After the collapse of Larsen A in 1995….. Drygalski Glacier was flowing three times faster in 2000 than prior to the collapse (Rott et al. 2002). In 2005, I find that Drygalski Glacier flows another 25% higher compared to 2000 …”
    “In 2002, Larsen B ice shelf collapsed in three weeks following more than 10,000 years of stability (Domack et al. 2005). Following the collapse, Hektoria/Green/Evans, Crane and Jorum accelerated eight and two times, respectively (Rignot et al. 2004b; Scambos et al. 2004). In 2005, I find that Crane accelerated by a factor of 2 compared to 2000 (figure 4b–d), and is now calving inland of its 1996 grounding line. Hektoria/Green/Evans slowed down 500m/yr, but are still 700% out of balance.”
    “On the west coast of Graham Land, Fleming and other glaciers have been flowing steadily since 1992. … but recent data showed that the region is 80% out of balance and Fleming Glacier flows 50% faster than in 1974, 50km inland of the grounding line (Rignot et al. 2004b).”
    [2.]“The glaciers draining the east coast from Drygalski to Leppard lost 27±9km^3/yr ice in 2002 (Rignot et al. 2004b) and 34±10km^3/yr ice in 2005.”
    “In Palmer Land, snow accumulation has increased by 10–20%… The interior gain in mass may therefore compensate the loss of mass at the coast. ”
    “Wilkins Ice Shelf is slowly[not anymore!-BD] disappearing. On the east coast, the mass balance of Larsen D and E glaciers is unknown. We know very little about ice flow changes in this part of the Antarctic Peninsula.” [No doubt this area is being studied intensively since the collapse of Wilkins. Given what happened with the glaciers feeding Larsen A & B, anyone care to make any bets on whether the glaciers here show positive or negative mass balance?-BD]

    @ Doug Bostrom 18 Jul 2009 at 4:05 am
    ““Changes in floating sea ice (even including “dramatic” events, such as the collapse of Larsen B and Wilkins) have no substantial impact on sea levels.” being a strawman argument – it doesn’t really matter whether it’s intended as a strawman, it is demonstrably wrong; although the immediate effects of floating ice melt don’t affect sea level, the sequelae (glacial acceleration) already being observed are contributing to sea level rise. The adages “hoist on one’s own petard” and “shooting oneself in the foot” leap to mind.

    In addition to the negative mass balances in the Antarctic, there are the observations of tropical glaciers. a good place to start is
    http://www.nichols.edu/departments/glacier/global%20glacier%20mass%20balance.htm
    There are about 15 links here to other studies.
    For a picture worth a thousand words, see
    http://www.nichols.edu/departments/glacier/cum%20bn.jpg

    There is also the accelerating ice mass loss from Greenland to consider
    from http://www.unep.org/geo/geo_ice/PDF/GEO_C6_A_LowRes.pdf
    “Total loss from the ice sheet more than doubled, from a few tens of billions of tonnes per year in the early 1990s, to about 100 billion tonnes per year after 2000,
    with perhaps a further doubling by 2005.” Future science will reveal what effect the decrease in summer albedo, caused by record Arctic ice melt, and the subsequent increase in Arctic ocean heat content, has on the weather, climate and the Greenland ice sheet.
    In the meantime, the numbers “representative of total global ice mass” are indubitably declining. Air temperatures may be experiencing an episodic shift to a pause in global warming, but ice loss is not. (TaDaaa! back on topic &;>)

    Comment by Brian Dodge — 20 Jul 2009 @ 12:22 AM

  379. Mr. BobFJ writes:
    “…the influence of melt water penetrating the cracks may be intuitively significant, but on closer inspection it is doubtful, because of the huge “thermal
    mass” that should rapidly freeze any water entering the cracks…”

    http://web.pdx.edu/~chulbe/science/Larsen/larsen2002.html

    points out a study by Weertman from the 1960′s discussing this topic.

    http://earthobservatory.nasa.gov/Features/WilkinsIceSheet/

    discussed meltwater ponds on Wilkins.

    Mr. BobFJ might, if he tried, find similar studies in Greenland. Perhaps he will.

    Comment by sidd — 20 Jul 2009 @ 12:23 AM

  380. BobFJ #369

    Your latest post is also unhelpful, and you continue to evade answering a simple question.

    Do you want me to rub it in? I linked you to SOHO MDI pictures of the Sun with their limb darkening intact. The one you showed, had it digitally removed, and you erroneously claimed that the Wikipedia picture is somehow inferior and “exaggerated”.

    I have news for you mate. Limb darkening is real and strong and you are mistaken. All it takes is a sunny day, one tube of a pair of binoculars and a sheet of white paper.

    You were wrong on an elementary radiation physics thing, while pontificating on radiation physics. That was my argument, and you’re the one doing the evading. Until I see you fairly admit it and save what is left of your credibility, nothing else is worth debating.

    Comment by Martin Vermeer — 20 Jul 2009 @ 1:21 AM

  381. Richard Steckis writes:

    I astounds me how some people can argue that the more data points one has, the less reliable is the statistical analysis.

    But that wasn’t what I was arguing at all. I was saying that you artificially inflate the number of points by chopping up the data too finely. Temperature has a cha-rac-ter-is-tic time scale of 30 years. Using monthly data gives you 12 times as many points, but the increased number of points doesn’t mean anything. Thus my analogy of 1-minute intervals for morning temperatures.

    The fact is the data points encompass nearly a decade not a single year.

    A decade is too short to mean anything where global temperatures are concerned.

    Your appeal to ridicule in you example is well…. Ridiculous.

    It has a serious point which apparently went over your head.

    Comment by Barton Paul Levenson — 20 Jul 2009 @ 2:52 AM

  382. manacker writes:

    It could well be that unexplained forcing factors and “unforced variability” are actually driving our climate as much as or to an event greater extent than the forcing from the assumed theory, right? I have seen no conclusive empirical evidence to the contrary

    Try here:

    http://BartonPaulLevenson.com/Correlation.html

    http://BartonPaulLevenson.com/Sun.html

    Comment by Barton Paul Levenson — 20 Jul 2009 @ 2:55 AM

  383. Chris

    You wrote (354): “Let’s look more closely at your new wriggle on this: You point out that the Hadley Centre Hadcrut analysis gives an extreme range of warming of 0.54 oC between 1910 and 1944. This is a highly cherrypicked time range (nice!) – and you like co2isnotevil’s suggestion that this warming could be due to sunspot numbers.”

    Not “cherry-picked” by me, Chris.

    This period has been cited, most notably by IPCC AR4 and in the study of Delworth and Knutson:
    http://www.sciencemag.org/cgi/content/full/287/5461/2246?ck=nck

    “Over the period 1910-1944 (which encompasses the warming of the 1920s and 1930s), there is a linear trend of 0.53 K per 35 years in observed global mean temperature.”

    “If the simulated variability and model response to radiative forcing are realistic, our results demonstrate that the combination of GHG forcing, sulfate aerosols, and internal variability could have produced the early 20th century warming, although to do so would take an unusually large realization of internal variability. A more likely scenario for interpretation of the observed warming of the early 20th century might be a smaller (and therefore more likely) realization of internal variability coupled with additional external radiative forcings. Additional experiments with solar and volcanic forcing, as well as with improved estimates of the direct and indirect effects of sulfate aerosols, will help to further constrain the causes of the early 20th century warming. Our results demonstrate the fundamental need to perform ensembles of climate simulations in order to better delineate the uncertainties of climate change simulations associated with internal variability of the coupled ocean-atmosphere system.”

    The study points toward co2isnotevil’s suggestion that this warming could be partially due to additional external radiative forcing from the high level of solar activity.

    To this topic you wrote: “recent estimates of solar contributions to early 20th century warming gives us perhaps a contribution of 0.1 oC for your 1910-1944 period”

    Actually, I believe there have been a few studies that have put the solar contribution somewhat higher, albeit over a longer time period. The average of about 8 studies I have seen have put the contribution from the unusually high level of 20th century solar activity at around 0.35°C over the entire 20th century (about half of the total observed warming). These studies point to a higher relative solar impact prior to around 1970 than afterward, but if your estimate has around one-third of the total value for around one-third of the time period that might make sense.

    Your other possible explanations are plausible, as well. Suffice it to say that Delworth had a bit of a harder time attributing the warming over this period than you did. In any case anthropogenic CO2 caused only a relatively small part of the total warming over the early 20th century warming period (around one-third), so we are basically in agreement.

    Max

    Comment by manacker — 20 Jul 2009 @ 3:30 AM

  384. CTG

    In your 364 you stated:

    “I haven’t seen you present any evidence – conclusive, definitive or otherwise – that melting of ice sheets does not influence sea levels. Any yet you quite categorically stated that ice sheet have ‘no substantial impact’.”

    There is no question that a significant shrinking of grounded ice either in the AIS, the GIS or non-polar mountain glaciers would result in an increase in sea level.

    So far, the latter has been the more important factor (of the three).

    Both the AIS and GIS were studied over a longer-term period 1992-2003, using millions of continuous satellite altimetry readings over the entire period. In both cases a slight increase in the size of the ice sheets was found.

    GIS increased from April 1992 to October 2002 (truncating one entire winter season) by 11 Gt/year mass gain, equivalent to an insignificant lowering of the sea level by 0.3 mm over the period.

    http://www.sciencemag.org/cgi/content/full/310/5750/1013
    “Averaged over the study area, the increase is 5.4 ± 0.2 cm/year, or ~60 cm over 11 years, or ~54 cm when corrected for isostatic uplift. Winter elevation changes are shown to be linked to the North Atlantic Oscillation.”

    http://www.ingentaconnect.com/content/igsoc/jog/2005/00000051/00000175/art00001
    “The Greenland ice sheet is thinning at the margins (−42 ± 2 Gt a−1 below the equilibrium-line altitude (ELA)) and growing inland (+53 ± 2 Gt a−1 above the ELA) with a small overall mass gain (+11 ± 3 Gt a−1).”

    AIS increased from April 1992 to April 2003 by 27 Gt/year mass gain, equivalent to an insignificant lowering of the sea level by 0.7 mm over the period.
    http://rsta.royalsocietypublishing.org/content/364/1844/1627.full

    “Our best estimate of the overall mass trend — growth of 27±29 Gt/yr−1— is based on an assessment of the expected snowfall variability. Mass gains from accumulating snow, particularly on the Antarctic Peninsula and within East Antarctica, exceed the ice dynamic mass loss from West Antarctica.”

    More recent shorter-term studies have shown a reversal of the growth in the GIS and a possible reversal of growth of the AIS, but in any case the contributions to sea level are relatively minor.
    http://www.sciencemag.org/cgi/content/abstract/315/5818/1529

    “Our best estimate of their combined imbalance is about 125 gigatons per year of ice, enough to raise sea level by 0.35 millimeters per year. This is only a modest contribution to the present rate of sea-level rise of 3.0 millimeters per year. However, much of the loss from Antarctica and Greenland is the result of the flow of ice to the ocean from ice streams and glaciers, which has accelerated over the past decade. In both continents, there are suspected triggers for the accelerated ice discharge—surface and ocean warming, respectively—and, over the course of the 21st century, these processes could rapidly counteract the snowfall gains predicted by present coupled climate models.”

    So the amount of sea level change attributable to mass reductions of the GIS/AIS are relatively minor to date, as I indicated earlier. Whether or not either becomes a significant factor in the future depends very much (as the studies have indicated) on whether or not the predicted accelerated ice discharge will counteract the predicted snowfall gains over the course of the 21st century. And the jury is still out on that question.

    Max

    Comment by manacker — 20 Jul 2009 @ 5:01 AM

  385. re: 307

    “[Response: If melt water pools on the surface and finds a crack in the ice, there is a strong pressure at the bottom of the crack since the water is denser than the ice. Thus there is a strong pressure gradient that (as long as the water doesn't freeze) will work to further deepen the fracture."

    Why must the water be denser than the ice for there to be a strong pressure at the bottom of the crack? And what is a strong pressure gradient?

    The pressure gradient in a column of liquid water is, to an excellent approximation, constant.

    Isn't it likely that when the water freezes that the volumetric expansion causes additional lateral strains.

    [Response: In a melt pond the level of the water is at the same height as the ice. Since the water is denser than ice (by about 10%), there is more water mass above the bottom of the crack than there is immediately to the side in the ice. Freezing might also play a role, but I'm not sure that would be relevant in some of the catastrophic melt-lake failures that people have observed in Greenland (I hear that multi-sq km lakes can sometimes drain in an hour or so). - gavin]

    Comment by Dan Hughes — 20 Jul 2009 @ 5:36 AM

  386. I have a question regarding paleoclimatology. Since land use studies have shown that the increased evaporation from irrigated land causes regional warming would this not also apply to the land irrigated by melting glaciers. As the glaciers disappear this land would return to a more normal state and the evaporation would decrease causing regional cooling. This would be a considerable factor when there is a lot of ice melting on land and much less so once the land ice has disappeared.

    Comment by stevec — 20 Jul 2009 @ 6:34 AM

  387. BobFJ
    19 Jul 2009 at 6:06 pm

    and believe that it is all intuitive chat

    How do you know
    this is ‘intuitive chat’. You must have read it. What does it say?

    Neither have I seen anything to confirm my belief that liquid water cannot exist within the huge “Thermal mass” of ice shelves, that are anywhere between around 100 and 1,000 metres* thick.

    The cracks take time to develop. As soon as a small crack appears, melt water water seeps into that crack, partly enlarging it and at the same time creating a deflection at the surface that attracts more melt water further away from the crack. As such a mechanism develops that can harvest solar energy at the surface over a large area and deliver it very localized inside the crack.

    Secondly, the cracks to not have to go all the way down to the bottom for the ice sheet to break up. Just deep enough to weaken it so mechanical stress can finish the job.

    Then there is also the seeping in of brine to consider, which will not freeze as easily.

    Sorry for my layman’s explanation, but that is the way I think it works.

    Comment by Anne van der Bom — 20 Jul 2009 @ 6:36 AM

  388. Steve, I don’t know about your question, but soil chemistry does change immediately after a glacier recedes: When glaciers disappear, the bugs move in:

    …Now the first study to look at how life invades soil immediately after mountain glaciers melt has an answer. Primitive bacteria step in to colonise the area, enrich the soil with nutrients, and even cement the ground, preventing landslides, say researchers who have studied the process in the Peruvian Andes.

    Comment by Jim Galasyn — 20 Jul 2009 @ 9:36 AM

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