RealClimate logo


Global trends and ENSO

Filed under: — gavin @ 4 July 2008 - (Español)

It’s long been known that El Niño variability affects the global mean temperature anomalies. 1998 was so warm in part because of the big El Niño event over the winter of 1997-1998 which directly warmed a large part of the Pacific, and indirectly warmed (via the large increase in water vapour) an even larger region. The opposite effect was seen with the La Niña event this last winter. Since the variability associated with these events is large compared to expected global warming trends over a short number of years, the underlying trends might be more clearly seen if the El Niño events (more generally, the El Niño – Southern Oscillation (ENSO)) were taken out of the way. There is no perfect way to do this – but there are a couple of reasonable approaches.

In particular, the Thompson et al (2008) paper (discussed here), used a neat way to extract the ENSO signal from the SST data, by building a simple physical model for how the tropical Pacific anomalies affect the mean. He kindly used the same approach for the HadCRUT3v data (pictured below) and I adapted it for the GISTEMP data as well. This might not be ideal, but it’s not too bad:



(Each line has been re-adjusted so that it has a mean of zero over the period 1961-1990).

The basic picture over the long term doesn’t change. The trends over the last 30 years remain though the interannual variability is slightly reduced (as you’d expect). The magnitude of the adjustment varies between +/-0.25ºC. You can more clearly see the impacts of the volcanoes (Agung: 1963, El Chichon: 1982, Pinatubo: 1991). Over the short term though, it does make a difference. Notably, the extreme warmth in 1998 is somewhat subdued, as is last winter’s coolness. The warmest year designation (now in the absence of a strong El Niño) is more clearly seen to be 2005 (in GISTEMP) or either 2005 or 2001 (in HadCRUT3v). This last decade is still the warmest decade in the record, and the top 8 or 10 years (depending on the data source) are all in the last 10 years!

Despite our advice, people are still insisting that short term trends are meaningful, and so to keep them happy, standard linear regression trends in the ENSO-corrected annual means are all positive since 1998 (though not significantly so). These are slightly more meaningful than for the non-ENSO corrected versions, but not by much – as usual, corrections for auto-correlation would expand the error bars further.

The differences in the two products (HadCRUT3v and GISTEMP) are mostly a function of coverage and extrapolation procedures where there is an absence of data. Since one of those areas with no station coverage is the Arctic Ocean, (which as you know has been warming up somewhat), that puts in a growing difference between the products. HadCRUT3v does not extrapolate past the coast, while GISTEMP extrapolates from the circum-Arctic stations – the former implies that the Arctic is warming at the same rate as the rest of the globe, while the latter assumes that the Arctic is warming as fast as the highest measured latitudes. Both assumptions might be wrong of course, but a good test will be from the Arctic Buoy data once they have been processed up to the present and a specific Arctic Ocean product is made. There are some seasonal issues as well (spring Arctic trends are much stronger the summer trends since it is very hard to go significantly above 0ºC while there is any ice left).

Update: A similar analysis (with similar conclusions) was published by Fawcett (2008) (p141).

The ENSO-corrected data can be downloaded here. Note that because the correction is not necessarily zero for the respective baselines, each each time series needs to be independently normalised to get a common baseline.


245 Responses to “Global trends and ENSO”

  1. 1

    Thanks for that. I had wondered if the 1997 Indonesia fires, which put out a huge amount of carbon, had made a large impact on the 1998 anomaly, but with the ENSO adjusted data it doesn’t seem to have had such an impact.

  2. 2
    Thomas says:

    Is it possible to tease out from the data whether there is a long term change in the ENSO cycle? Can we tell if the frequency or strength of events is changing? Is one phase becoming more common than the other? Or is the length of time of decent data just too short?

  3. 3

    This is a wonderful post and much needed in the blogosphere debate with the junk science experts — thanks so much!

  4. 4
    Craig Allen says:

    Has anyone looked at trends in other climate/weather parameters besides temperature that might help explain the more rapid than expected decrease in ice cover? For example, wind or ocean current speed and direction.

  5. 5
    Ian K says:

    Can you give some idea of the geographical extent of the area warmed by an el nino event?

  6. 6

    Looking at the HadCRUT3v ENSO corrected graph,it seems as though the temperature has flattened out since 1998. Could that be due to the melted Arctic ice being flushed into the Atlantic? See:
    http://www.homerdixon.com/download/arctic_flushing.html

    Cheers, Alastair.

  7. 7
    Patrick Hadley says:

    For how long has it been agreed that short term trends are not meaningful?

    When James Hansen went before Congress in 1988 he made a great deal out of what was at that time a short time trend. As can be seen from your graph there had been a slight falling trend in global temperatures between 1950 and 1976. The graph he used had a five year moving average which showed that temperatures had been generally declining during the 36 years 1940 to 1976. But the shortness of the warming period did not stop Hansen explaining to Congress the statistical significance of the rising trend that had occured during the 12 years before 1988.

    [Response: Since always. Hansen did not make his points because of a short-term trend in temperatures but because the long term trends were a match to the expectation he had from the physics. And he was right. - gavin]

  8. 8
    Mauri Pelto says:

    I remain particularly curious with respect to the reinforcing or damping potential of the PDO on ENSO. Only when both are negative for example do we see positive mass balances on Northwest North American Glaciers, as was the case this winter
    http://www.the-cryosphere.net/2/13/2008/tc-2-13-2008.pdf. The forecasting of El Nino has improved amazingly in the last decade http://www.cpc.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf
    Are there any plans to incorporate the Arctic data into the global temperature data sets, or is it too short term to adequately do this?

  9. 9
    Dan Hughes says:

    … (which as you know has been warming up somewhat) …

    I read the post given at the link (I have not read all the comments). I do not see that the state of the Arctic sea ice has been shown to be dominated by the thermal processes typically associated with increases in the temperature of either the air or water at the North Pole.

    There are several physical processes that can account for a decrease in the mass of ice and its spatial extent at the North Pole. It would be nice to see definitive statements that at least rank the physical causality possibilities, and supporting data, that seem to be at work at this time. Are air and water temperature data at the North Pole available that indicate that these have recently increased? Doesn’t the fact that about 90% of the ice is under water seem to indicate that the water temperature might be more important that the air temperature? Even a list of those that can be eliminated, to the extent possible, would be helpful relative to getting a handle on causality.

    Mother Nature works based on causality conditions at the temporal and spatial locations of interest. Time-series plots summarize the effects, not the dominate physical causality processes at work.

    Thanks

  10. 10
    Patrick Hadley says:

    I am not sure how anyone can look at James Hansen’s graph of global temperature history in his 1988 presentation and say that there was a long term warming trend at that time. Look at the five year moving average line on his graph and see that the steep rising trend only began in 1976. His five year moving average trend line appears to be around 0.2 degrees lower in 1976 than it was in 1940.

    Better still, get rid of the (weather and El Nino influenced) short-term five year averaging and show long term climate changes by putting ten and twenty year moving averages on the data. Both those lines are pretty flat for about 20 years until around 1978. Can 20 years of flat temperature trend plus 12 years of increase equal a long term trend?

    [Response: yes. - gavin]

  11. 11

    Gavin, may I please copy this post to my own blog? I get about 2,000 hits per month, now, and the people who look at my blog are looking for just this type of info. Thanks

    [Response: sure - gavin]

  12. 12
    Hank Roberts says:

    Patrick Hadley, as a reminder, you can put your name +Hansen +trend into a Google Search to review past answers to the same question. People seem to answer it the same way each time you raise it.

  13. 13
    Sean says:

    What is the underlying cause of El Nino and La Ninas? They have apparently been going on for centuries but why? The amount of energy difference is huge and I don’t think that many people would argue that they don’t have a significant impact on the global temperature in the short run. Why and how does the pacific store up all that energy for an El Nino and then release it?

    I don’t think I am wording this well but hopefully you get my drift (pun partially intended).

  14. 14
    Luis Dias says:

    If you also take out the pinatubo volcano event, it is also clear that the shown trend in the graph given here is a negative acceleration curve. This strikes to me as contradictory to the speech that we are upon a runaway climate change process. I welcome that news. Given peak oil and peak coal to happen in the first middle of this century, I also harbor the probable heretic notion (in here at least) that little changes will be required to be made in the political scene.

    I will refrain to redirect my reply to interesting sites (which I have nothing in common with) that develop this point so that no one will accuse me of trolling around.

  15. 15
    Steve Reynolds says:

    “You can more clearly see the impacts of the volcanoes (Agung: 1963, El Chichon: 1982, Pinatubo: 1991).”

    It would be interesting to see a similar graph with the effect of the volcanoes removed.

  16. 16

    #6 Alastair, In Canadian slang : nopes… Apparently not, look at NH data
    http://data.giss.nasa.gov/gistemp/tabledata/NH.Ts.txt
    There has been a net warming in the Northern Hemisphere as to compared to the entire globe.
    Warmest year in NH history was 2007, the year of the great melt.
    2008 is in a class of its own, it started with a cooling impact from the lack of clouds in the Canadian side of the Arctic. It would be again good to have global cloud coverage vs temp graphs, I am sure they look a bit the same. Not to say it has any cosmological reasons to be nearly identical, clouds play a big role in surface cooling or warming. Note the key word SURFACE, I have yet to see a DWT
    global graph! Although someone may be working on this. A Density Weighted Temperature plot
    of the entire troposphere makes cloud driven surface temperature variations obsolete, temperature anomalies become far smaller, the Global trends would essentially become less jagged.

    Removing ENSO from the picture is a great idea, and behold, the world is a warming despite it.
    A great Post again, RC is #1 on climate despite annual variations in tempers…

  17. 17

    it is also clear that the shown trend in the graph given here is a negative acceleration curve.

    The attenuation is due to several well known buffers in place, buffers which are now being actively diminished.

  18. 18
    Steve Mauget says:

    I’m confused by a study that tries to subtract out a climate system response that influences a substantial chunk of the Pacific Ocean basin to get at the planet’s “true” temperature response to anthropogenic greenhouse gases. Although I haven’t read the Thompson et al paper, the assumption seems to be that ENSO variability and the global temperature trends related to increasing CO2 levels are unrelated. But how do we know that?

    How do we know, for example, that the 1997-98 warm phase period in the Pacific was not linked to GHG forcing? I’m not a close follower of the literature in this area, but has someone done an attribution study showing that the 97-98 event – or general ENSO variation in the past 30 years – would be unchanged in the absence of increasing anthropogenic GHG forcing?

  19. 19
    Lowell says:

    CO2 levels have increased from about 308 ppm in 1950 to 385 ppm in 2008. It appears that temps have increased by about 0.55C

    Are we able to extrapolate something about the CO2 sensitivity from these figures?

    [Response: No. i) the temperature is not in equilibrium with the forcing (that takes time) and ii) CO2 is not the only forcing - you need to factor in aerosols, other greenhouse gases etc. - gavin]

  20. 20
    David B. Benson says:

    Steve Mauget (18) — Indirectly peraining to your quexstion, I recommend reading “Earth’s Climate: Past and Future” by W.F. Ruddiman. At a minimum, this will improve your intuitions.

  21. 21
    Gary P says:

    I really like the second graph in this article. It looks like temperatures are starting to level off, despite a higher CO2 level and CO2 rate of increase in the atmosphere. Sweet

    [Response: Brought to you by the magic of natural variability... - gavin]

  22. 22
    Steve Reynolds says:

    “Brought to you by the magic of natural variability… – gavin]”

    How do we know that recent temperatures are not typical, and that 1950 to 1978 temperatures were not unusually low due to natural variability?

    Could a climate sensitivity of around 1.5C also be consistent with this data?

  23. 23

    #13 Sean
    Gavin

    Has anyone overlaid the 11.1 solar cycle (9-14 yr. avg.) over the El Nino/La Nina cycle?

    I’ve been thinking about what drives the cycle and that thought has popped up in my head several times over the past few years.

    With a .3W/m2 variance that’s a pretty good booster, just wondering it the overlay graph would match up?

    The 1998 was in the upswing of the sunspot cycle activity so I’m curious if this pattern is fairly well repeated and what other complications might be attached to the influence.

    #22 Steve Reynolds

    Natural variability is what it is. You seem to be happy about a leveling off trend even though we are essentially in a cool phase with low sunspot activity and La Nina occurrence. Will you also say “sweet in a few years when sunspot activity is peaking again and we get another El Nino?

    not to oversimplify, but while natural variability occurs, that does not mean that the overall climate system is not operating outside of natural variability when it comes to forcing levels, which are not calculated around 1.9 W/m2 when considered with all the positive and negative forcings (aerosols, moisture, clouds etc.).

    The ’1950 to 1978′ (1942 to 1978) temps were likely due to aerosol pollution. We can always go back to producing sulphates and CFC to cool the planet I suppose, but how much do you like acid rain and skin cancer and all the other wonderful respiratory disorders we gained from that type of pollution? natural variability of course is always at play on top of anthropogenic influence in our modern era.

  24. 24
    David B. Benson says:

    Steve Reynolds (22) — Using the stand formula for temperature increases due to addional CO2, I compared 1958 CE (315 ppm) with 1850 (288 ppm) and obtained the average temperature increase for the 1850s decade to the 1950s decde, close enough.

    So by this one, kinda crude, measurement: no, climate sensitivity is close to 3 K.

    To see that it cannot be as low as you suggest, read Gregory et al. (2002).

  25. 25
    Joseph says:

    Are we able to extrapolate something about the CO2 sensitivity from these figures?

    [Response: No. i) the temperature is not in equilibrium with the forcing (that takes time)...]

    Is there an official figure on the lag? If it’s known you could calculate the sensitivity, right? After looking at the data, it appears that the lag is about 8 years for a fluctuating trend. It would be more for a long-term CO2 increase. It might not even be catching up that way. With an assumption of 8 years, the average effect I see is 0.015 degrees (C) for every extra 1 ppmv CO2 in the atmosphere. The relationship appears to be completely linear.

  26. 26
    Mauri Pelto says:

    #12 Hank you are a natural science detective.

  27. 27
    Jeff says:

    Off Topic: Gavin, I was intrigued by some of the articles in the June 13th issue of Science Magazine. Is there any chance of getting a guest contribution summarizing the state of Dynamic Global Vegetation Models and how they might be incorporated in future GCMs?

  28. 28
    Steve Reynolds says:

    David B. Benson: Using the stand formula for temperature increases due to addional CO2, I compared 1958 CE (315 ppm) with 1850 (288 ppm) … climate sensitivity is close to 3 K.

    Any estimate based on that small CO2 change is extremely crude…

    Benson: To see that it cannot be as low as you suggest, read Gregory et al. (2002).

    I looked at Gregory; they also say 1.1K is possible with different assumptions. Also, I wonder what the result would be if their methods were repeated with recent data?

    Another paper showing 1.2K as possible:
    http://www.jamstec.go.jp/frcgc/research/d5/jdannan/prob.pdf

  29. 29

    #25 Joseph

    I am not an expert but I do have two cents to throw in. The forcing is at 1.9W/m2 so it will take more than 8 years for the oceans to absorb the forcing. Of course as they absorb the forcing, they will release more moisture. There is apparently a great amount of learning still in the cards on clouds but this is a pretty big forcing. I’m not expecting things to cool down anytime soon.

    More moisture means positive feedback. There has been a 4 degree latitudinal shift, which i believe was expected of the jet stream system. I’m a pilot, so I relate that to how we measure air density. Hot air expands, so when we try to get our aircraft of the ground, if it’s hot, it’s harder to get enough air over the wing to produce enough lift.

    As things heat up, I would therefore expect that hotter air will create less dense air and that said, air expansion would push the jet streams north and south as the tropics get more sunlight and the heat is trapped in the climate system, and absorbed slowly by the oceans.

    That will have an effect on the geometric absorption of heat I suppose, relational to the amount of GHG’s at a given time and the amount of earth absorbing the solar radiation.

    So with the increase of heat trapping gases and the positive feedback of increased water moisture, which is of course also a greenhouse gas, in the atmosphere. I’m just expecting things to get warmer, which in turn will make things warmer.
    i.e. positive feedback.

    I doubt any 8 year trend is significant to ocean absorption lag time.

    Gavin already pointed out that you have to add the aerosols and other gases, then you have to consider effects.

    The amount of time for the lag absorption rate is also relational to the type of gas doing the forcing. While Methane and Nitrous oxide gases are more short lived, Co2 is long lived in the atmosphere, so stopping some of the gases will not eliminate the long term forcing on the oceanic thermal absorption. The lifespan of atmospheric Co2 is pretty long, retaining still 25% over hundreds of years.

    So lag time has to be understood in connection to the type of GHG and the lifetime of the GHG. Add em all up and you can start to draw a picture.

  30. 30
    sdw says:

    Are we able to extrapolate something about the CO2 sensitivity from these figures?

    [Response: No. i) the temperature is not in equilibrium with the forcing (that takes time)…]

    So where is the missing temperature? I presume some form of lag via the oceans. However the ocean temperatures are not recently rising (the ARGO data set), and a strong and consistent trend should be observable with consistent CO2 increase. Is this correct?

    regards, sdw

  31. 31
    iceman says:

    #23.
    “The ‘1950 to 1978′ (1942 to 1978) temps were likely due to aerosol pollution. We can always go back to producing sulphates and CFC to cool the planet I suppose, but how much do you like acid rain and skin cancer and all the other wonderful respiratory disorders we gained from that type of pollution? natural variability of course is always at play on top of anthropogenic influence in our modern era.”

    Look at the waxing and waning of the solar cycles. Solar cycle #20 was relatively low and long. Is it just coincicdence that a cooling period occured during cycle 20? Is it a coincidence that the Dalton Minimum during solar cycles 5 and 6 produced notably cool temperatures? Is it a coincidence that temperatures are starting to go down after a relative long solar minimum between cycles 23 and 24? What about the little ice age durning the Maunder solar minimum in the mid to late 1600′s? Why attribute it to aerosols when a direct relationship between weak solar activity and cooler temperature can be seen. It could be just a coincidence but sure looks good to a layman such as myself. The people posting here are a lot brighter than I am. I just cant let go of solar/climate connection. There are some smart people like the fellow who heads up one of Russia’s space related agencies, Habibullah Abdusamatov.
    He strongly beleives that it is the sun that is the primary driver of climate. I was directed by a knowledgable poster to check out the discrediting of solar cycle influence on climate. I did so and was almost swayed to that opinion. But I still have a lingering though unfounded suspicion that variations in the solar output should be given more higher weight in the climate models. We are now in a pretty deep solar minimum. Temperatures have start to fall this year. There may be a significant lag between solar min and consequential global temp decrease. If the solar minimum continues and temperatures continue to drop then the influence of solar cycles should be given more consideration. If the minimum continues and temperatures continue to rise then I will abandon the idea that climate follow solar activity. It will take only one or two years to convince me of that.

  32. 32

    #23 John P. Reisman

    Okay, I type too fast, my apologies.

    “which are not calculated around 1.9 W/m2″

    is supposed to be

    which are ‘now’ calculated around 1.9 W/m2

  33. 33
    iceman says:

    Could it be that PDO and AMO are subharmonics of solar forcing?

    A post from solarcycle24.com:

    Hansen predicted in 1988 that we would be considerably warmer now than we are. That’s a fact.

    The past decade, at the very least, has not seem the same rate of warming as the previous two decades (all natural variability such as ENSO accounted for). Also a fact.

    NASA predicted in 2006 that if an El Nino formed later that year, or in 2007, a new global temperature record “would almost surely” be set. The El Nino formed, but neither 2006 or 2007 came close to 1998. The 2007 IPCC report states that they expect half the years from 2009-2015 to be warmer than 1998.

    It is clear that “climate science” expected, and still expects, more warming than what has been observed. None of this “oh, natural variation and cool spells are expected to interrupt the warming (for more than a year or two)” crap…that’s not what has been predicted, and if temperatures do not rebound in a big way soon, AGW projections will continue to look foolish.

  34. 34

    #33, Iceman: do a graph of Northern Hemisphere annual temperature anomalies
    from here:

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

    Is my understanding that CO2 has far greater impact overland than sea. But the facts speak about a noticeable warming.

  35. 35

    that’s not what has been predicted, and if temperatures do not rebound in a big way soon, AGW projections will continue to look foolish.

    Why? There are plenty of places for that heat to go. I can think of three of them offhand, besides the obvious.

    The portals in and out of these places are very fluid.

  36. 36

    #31 iceman

    Climate is not driven only by solar though. Some of what you are saying may be or likely is coincidence. As is known correlation is not necessarily causation. Cherry picking data and narrowly scoping the view does not help either. That was the UAH problem and it led them to eventually be proven wrong in their base assumptions because they did not look at the big picture. That was also the problem illustrated in the Great global warming swindled movie, where they represented only the data that matches and stopped the data set where it no longer matched because it did not suit their purpose of trying to trick people in to believing something that was not true.

    Apples and oranges are not the same but both are tasty. The Maunder minimum is natural cycle/variability. But you have to look at variability and geologic time scale in relation to the forcing components.

    As far as the sun being the primary driver of climate, absolutely. if you take the sun away, we would not have climate to be concerned about, nor would we be here. I am oversimplifying with a purpose.

    Climate is driven now by components of natural variability and human components added to the forcing of the climate. We are actually quite far outside of natural variability on the recent trend. There has thus far been no model or even substantive reasoning that can explain this recent warming.

    Only looking at solar is cherry picking too though. DOn’t forget there are lots of things actin on climate. Eccentricity, Precession, Obliquity. Oceans and algae (co2 absorption) methane, nitrous oxide. co2 High GWP’s albedo changes cloud pattern shifts moisture content etc.

    From what is currently known, if we were following natural variability, we should be cooling more. But we are not. So something changes. The

    If I were to follow your logic, then when we should have been warming during the 40s and 50s because solar cycle 17, 18 and 19 were each progressively stronger. But at that time we were producing a lot of sulphates and other aerosols that helped cool the planet but that is also complimented by natural variability.

    It is too easy to oversimplify or cherry pick your data and reasons for climate. When everything is looked at in context and with relevance to the forcing added and taken away and placed in the context of natural variability, then the picture not only becomes clearer, it matches the models quite well.

  37. 37

    #33 iceman

    Cool down iceman, your starting to warm.

    I don’t know about your “fact” about Hansens prediction. The 1988 model when revisited in 2006 was pretty much on track in scenario B which was presented as the most likely scenario.

    Here are some facts, the long term trend is up, and there is more warming in the pipeline. There is no reason to expect a trend reversal (unless you have some new data and modeling you would like to share (that has made it through peer review and peer response and survived)) to to the amount of forcing in the system, the lifetime of Co2 in the atmosphere, the human industrial output and the oceanic thermal inertia and lag time for absorption. AGW projections are not foolish, they are science, and extremely well founded, not to mention that little consensus thing among relevant climatologists that are working in the field on a daily basis.

  38. 38
    tamino says:

    Re: #33 (Iceman)

    … neither 2006 or 2007 came close to 1998.

    According to GISS analysis, 2007 tied 1998. That’s not close enough for you? You’re the one looking foolish.

  39. 39
    Lamont says:

    the el nino that preceeded 1998 was much stronger and longer than the el nino that preceeded 2007.

    just summing up the monthly ENSO values prior to 1998 and prior to 2007 i get +22.2 for 1998 and +5.2 for 2007 (approximating an area-under-the-curve to try to gauge the magnitude of the whole event).

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

    also, unless my eyeballs are deciving me (i’m staring at monthly NASA data which is a lot of numbers), Jan 2007 was the warmest (by temperature anomoly) month ever, and Dec/Jan/Feb around that month was the warmest 3 month period.

    http://data.giss.nasa.gov/gistemp/tabledata/GLB.Ts+dSST.txt

    so we’re almost there. a little larger of an el nino or a few more years of AGW and the 1998 record should be soundly broken.

  40. 40
    Craig Allen says:

    Iceman,

    Every year since 2000 have been warmer than any year prior to 1998. I don’t see how that squares with you assertion that AGW projections look foolish.

    I gather you have at hand some kind of statistical analysis that demonstrates your subharmonic of the solar forcing theory. Lets see it then. Some details about the mechanism would be of interest also.

    Can you point to any temperature predictions made in 1988, which were based on the assumption that there is no CO2 induced warming, that were more accurate than Hansen’s prediction?

  41. 41
    dhogaza says:

    None of this “oh, natural variation and cool spells are expected to interrupt the warming (for more than a year or two)” crap…that’s not what has been predicted.

    Please reveal the sources in which climate scientists have proclaimed that AGW will put an end to natural variability.

    It’s the first I’ve heard of it …

  42. 42
    peterg says:

    Curious how this correction wasn’t found necessary for particularly warm years. One imagines there was some great advance in the mathematics involved.

    [Response: Don't imagine. Try reading instead (umm.. 1998?). - gavin]

  43. 43
    pete best says:

    Re #33, there are still large error bars in temperature rises due to soot, black carbon and aerosoles and hence temperature rise predictions are cautionary in nature. The big factor remains that GHG theory when modelled up to AGW theory takes notice of the Arctic and in the Arctic AGW is seemingly correct.

  44. 44
    mark says:

    Re #28
    “David B. Benson: Using the stand formula for temperature increases due to addional CO2, I compared 1958 CE (315 ppm) with 1850 (288 ppm) … climate sensitivity is close to 3 K.

    Any estimate based on that small CO2 change is extremely crude…”

    Why then did you ask about 1950-1978? That’s, ooh, 29 years. cf 109 years David used.

    iceman at 31, do the calculations and see if the changes in solar output explain the MAGNITUDE of the change.

    I find it odd that when the small forcing of CO2 is brought up people say it’s a miniscule change, even though the trend is there, but when someone says it’s the Sun, even though that is a miniscule change, they see the trend immediately.

    Is that purely because one is their fault and the other not, so seeing a change is acceptable in one and not the other?

  45. 45

    iceman writes:

    It is clear that “climate science” expected, and still expects, more warming than what has been observed. None of this “oh, natural variation and cool spells are expected to interrupt the warming (for more than a year or two)” crap…that’s not what has been predicted, and if temperatures do not rebound in a big way soon, AGW projections will continue to look foolish.

    iceman, the World Meteorological Organization (WMO) defines climate as “mean regional or global weather over a period of 30 years or more.” Do you suppose they just picked that figure out of the air? A few years of apparent cooling don’t really mean much, especially when you’re starting with the hugest El Nino on record (1997-1998) and ending with the largest La Nina in 20 years (2007-2008).

  46. 46
    PeterK says:

    @33
    “Hansen predicted in 1988 that we would be considerably warmer now than we are. That’s a fact.”

    That’s not a fact. It was discussed in length. It was a false accusation from a guy called Crichton. That is how false accusations turn into so called “facts”. Solar influence on climate is discussed in the IPCC report.

    Concerning the Russian guy, he should publish his findings. They will be reviewd and discussed. About the litte ice age: Well, in 1600 global satellite technology was not exactly as good as nowdays and precise weather data from Africa or South America for this period ist hard to obtain. If there was such a thing, it was most likely not caused by aerosols.

  47. 47

    Concerning the Russian guy, he should publish his findings. They will be reviewd and discussed. About the litte ice age: Well, in 1600 global satellite technology was not exactly as good as nowdays and precise weather data from Africa or South America for this period ist hard to obtain. If there was such a thing, it was most likely not caused by aerosols.

    I’m unclear on the “If there was such a thing” comment. I know there is a strong tendency of most pro-global-warming posters here to ignore that giant ball of fire and its cyclical behavior, but on what planet does ignoring the Dalton and Maunder Minimums make sense? And when the Gore Minimum brings another short term cooling trend, how do you propose explaining that so people understand the difference between short term cooling, long term warming, and the need to do something?

  48. 48
    PeterK says:

    Fair enough, he published a little bit on the Pulkovo site. There are some documents in English (or they have an English abstract), most of it is in Russian (I do not speak Russian), but you get an idea what he wants to say. He needs to be taken into consideration, because he is in charge of some important experiments on the ISS. I think that the theories presented on his site are not well founded. If somebody speaks Russian, a translation would be helpful. Just google for Pulkovo, Laboratory of space research. Why are they not well founded?

    Quote from the site:

    “A year ago, many meteorologists predicted that higher levels of carbon dioxide in the atmosphere would make the year 2007 the hottest in the last decade, but, fortunately, these predictions did not become reality. Hence, increase of carbon dioxide concentration in the atmosphere is not the cause of global warming which has a solar origin and is a part of natural two-century cycle”

    This was discussed over and over. We are talking about long term trends. His conclusion that one year (2007) falsifies the AGW theory is – let’s call it a bit strange. And there is no clear evidence presented for his assumed “two-century” cycle.

  49. 49
    Joseph says:

    He strongly beleives that it is the sun that is the primary driver of climate.

    The data suggests otherwise.

  50. 50
    Mark says:

    Re #48

    It even gets the cart before the horse.

    This could still explain:

    2007 would be 2.0 degrees warmer because of CO2. A normal El Nino would have cooled by 1.0 degrees. It would have been 1.0 degrees warmer. This would be a maximum.

    However, a strong El Nino would have cooled by 3.0 degrees. Therefore, 2007 with a strong El Nino (which could not be forcast at that time) was 1.0 degrees cooler.

    And there’s a huge logical jump there to say that just because 2007 wasn’t the warmest, that CO2 can’t cause global warming. I mean, did it before then, but the universe noticed that 2007 *wasn’t* warm and change the physics???


Switch to our mobile site