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Unforced Variations: July 2013

Filed under: — group @ 1 July 2013

This month’s open thread…

We have just updated the blog software, and are taking a little time to assess how up-to-date some the content is (including the theme, mobile theme, blogroll, about pages and the RC wiki etc.). So this might be a good time to chime in with your suggestions as well as discussing the latest climate science issues.

350 Responses to “Unforced Variations: July 2013”

  1. 301
    Chuck Hughes says:

    Okay, let’s at least establish a baseline for further discussion…

    Is there anyone on this web site who DOES NOT think we will reach 500ppb of CO2 by or before the end of this century????

    If you don’t think this will happen please explain why. Otherwise, is there any real reason to believe humans are going to survive?

  2. 302
    Hank Roberts says:

    > use google yourself

    That drilling program the article you cited said would
    be completed late in 2012.

    I did.

    But I’m not the updater for your blog.

    Carry on.

  3. 303
    Ray Ladbury says:

    Chuck Hughes,
    I am pretty sure we’ll be over 500 ppmv. I don’t think that will necessarily be the end of human civilization, let alone of humanity. That said, our progeny will be in for a world of hurt. We will see a large decline in human population. I think humans will survive. The question is whether it will be in a global civilization or as small bands of hunter-gatherers.

  4. 304
    James Cross says:


    You are far too pessimistic.

    We will probably exceed 500 but I would project the rate of increase to slow during the second half of this century as alternative energy technologies begin to predominate.

    Even so, we won’t be reduced to hunting and gathering.

    Consistently the doomsayers underestimate technological progress. Erlich’s population projections were right but the starvation he projected failed to materialize because of agricultural technological progress. I see no reason for this progress to stop. We will develop new crops and more intensive means of farming that require less energy than the techniques in use today. Expansion of health resources, improvement in sanitation, and general economic growth in the developing world will slow population growth. The right sort of alternative energy technologies might be adopted in the developing faster than in the developed ones – just as developing countries skipped line telephone lines and went straight to cell phones. This is key if we intend to slow CO2 increase overall for the planet because the most recent increases have come with a declining contribution from the U.S. as we have switched to natural gas for power generation.

  5. 305
    Ray Ladbury says:

    James, Technology is not magic. There are limits to what it can do–and among those limits is support 10 billion on a planet that would strain to support 1 billion. All technology does is increase the population overshoot and the damage done to the planet.

    I agree that 500 ppmv won’t reduce us to hunter-gatherers, but 800 might, and I see no sign we’ll avoid that.

    In any case, I’m not sure where this new technology is to come from since we aren’t even investing in basic science anymore.

  6. 306
    patrick says:

    July 24–President of the Reinsurance Association of America, Frank Nutter, testifying before Senate committee, notes Munich Re view (mentioned #221):

    ClimateState post with video says: “The…point is…insurance companies live and die by their ability to estimate risks.”

    Frank Nutter: “Reinsurance…is science based. Blending the actuarial sciences with the natural sciences helps us with an understanding about climate and its impact on a variety of weather conditions.”

    Those who live by factual estimates about climate: practicing climate scientists, reinsurers, the U.S. Navy… Let’s see, who else…

  7. 307
    Omar Cabrera says:

    When I referred to the “huge methane venting episode” in East Antarctica I based this on observations of data coming from IASI, not AIRS. My experience with Giovanni/AIRS is mixed. I stopped using it beginning of January 2013 after it didn’t pickup any data for a couple of days on the area I was watching in the Arctic and switched to IASI as my main source of methane data.

    I also would like to mention that:
    - The goal of the two videos wasn’t to report on that methane venting episode, but to explain how to use the “Unified methane layers” functionality on It just happens that the venting episode in Antarctica was the largest one in the world since January 1st. (start of data in methanetracker) in extent and duration and I used it as an example just because of that; and
    - Dr. Yurganov watched these videos before they were public, as we rely on his technical advice, and we wanted to have his blessing before making the videos public on YouTube.

    That being said:

    There are very few instruments measuring methane remotely: AIRS, IASI, CrIS and TANSO for the GOSAT project are the ones I’m aware of. Of those, AIRS and IASI are the only two instruments that were serving information publicly and after AIRS stopped serving data publicly in Feb. 28 2013 (this venting episode started beginning of Feb.), IASI is the only instrument measuring CH4 that provides public data (that I’m aware of, I could be wrong).

    So the real question is. Is the data from IASI reliable?

    CH4 remote readings are not exact yet and won’t be for several years more, but they’re not that inexact either. We do have some non-remote almost exact CH4 measurements. They were measured by the HIPPO aircraft missions.

    Consider X. Xiong et al 2013 validation of IASI data:

    Xiong et al uses the HIPPO missions CH4 readings to validate the remote readings from IASI. They found that the error of the IASI CH4 remote readings is up to 1.5%, at high hPa and it increases with the latitude, but it seems to be under 0.5% around the 586hPa which is where most of the East Antarctic methane is (Fig. 9 shows the error).

    On the other hand, you can compare IASI, AIRS and CrIS here (this is a presentation by Xiong, same author of the paper):


    - Are IASI’s readings “exact”? No, they’re not.

    - Can you trust them enough to report that there is an East Antarctic methane venting episode? I think the answer is yes. Even in the absolute worst case scenario, the margin of error in Antarctica at 586 hPa shouldn’t be more than 5% (and I may be wrong, please correct me if I’m wrong), with a likelihood between 2% and 3%. At 2200ppb even if you count a 5% extra on EVERY SINGLE READING reported on an absolute worst case scenario, the result would still be more than the 1950ppb in yellow off the color chart.

    Is this an artifact? You can draw your own conclusions: Read both (paper and report) by Xiong et al mentioned above, and then check the original IASI readings on the apocalypse4real website: or you can run on a methane chart (data/interactive methane charting) and run a methane avg. ppb x hPa x day for Antarctica, for any period between March and July (a few days should be enough to make the point). After it processes the graph, it will show the original data from IASI under the graph with a link to the original image. Whatever you see in yellow is more than 1950ppb.

    The original image from IASI also has the ppb range.

    I think that there is a methane venting episode going on, but I also think that it means what it means. It means that this is a big and potent unexpected source of methane. It also means that our computer simulations have a LONG way to go, and it also means that field research must be done.

    How much methane is there under East Antarctica? a lot less than under the ESAS. That much we do know. There are few things more we know without further research.

  8. 308
    James Cross says:

    Any thoughts on this and whether it might also apply to climate models?

  9. 309
  10. 310
    Tony Weddle says:

    #292 I dug a little more (it’s difficult to find much information or data on current CO2_e) and found an old RealClimate post from 2007, which addressed this subject. It looks like I might have been overlooking aerosols negative forcing. That article stated that the effects of aerosols is (was) highly uncertain but a good guess is that, overall, the CO2_e figure is close to the CO2 figure. That would put us about 400 ppm CO2_e, if the same applied now. However, using a factor of 25 for CH4 doesn’t seem right, at a time when CH4 is increasing. If we used a factor of 75 instead (since the amount in the atmosphere this year is more than last year, though a factor of 100 seems better), then we’re well through the notional limit of 450 CO2_e. Have I got something wrong and is there better information on current CO2_e?

  11. 311
    Omar Cabrera says:

    Oops, sorry! I was looking at the comments at the end of page 6. Didn’t mean to change the subject.

  12. 312
    prokaryotes says:

    Omar Cabrera, what do you think of Yurganov’s and other comments, about the Methane

  13. 313
    Dave123 says:

    Question for people intimately familiar with climate modeling code. Do any of them use random number generators in them-with the purpose of creating small random perturbations in the systems with time for probabilistic assessments (Do 1000 runs and see what it looks like) or are they strictly deterministic?

    Has anyone read this paper and wish to describe what they’re talking about:

    I can’t find a reference to a comparable study on other modeling systems, but that may be a keywording problem.

  14. 314

    #307–Thanks for expanding upon the capabilities we currently have. Based upon what you said, it certainly seems likely that there was indeed something going on.

    If we see the signal at the 586 hPa level, how closely can we constrain the origin of the methane? A naive question, perhaps, but I’m very aware that I know almost nothing about how methane mixes (or doesn’t mix) in the atmosphere, or about how atmospheric circulation would affect methane being vented from the surface in February.

  15. 315
    David B. Benson says:

    Dave123 @313 — Hong et al. note in the abstract that there are variations between computers due to different hardwear implementations of round-off. Is that what you needed.

    As for your first question AFAIK the codes do not use pseudo-random number generators. It is typical to repeat runs using slightly different initial conditions to establish variation.

  16. 316
    Chuck Hughes says:

    So…. if you were to take the current rate of CO2 increase on a per year (BAU) basis and extrapolate outward say, two decades from now, what would be the approximate level of CO2 in ppb by 2033? Or, how many ppb are we adding each decade at our current rate of increase?

    Because the transition over to renewable energy might slow the progression down and we don’t know how quickly that would happen, let’s assume that the rate of CO2 stays the same as it is today and go with worst case scenario, since that’s what we want to avoid. How long, theoretically, would it take us to get to 500ppb?

    I’m thinking if we reach that level we would be noticing some drastic changes in weather patterns way beyond what we’re seeing now. Would CO2 levels at 500ppb take us far past the 2 degrees Celsius target set by the IPCC?

    And to take it one step further… is there a “known” level of CO2/temperature where reversing the situation becomes impossible within the next several centuries? I’d like to know if there is an established consensus amongst scientists concerning a “point of no return” on temperature/CO2 levels.

    I realize this is not a new question for climate scientists but since we’re in an ever changing situation I think an update based on current trends would be helpful.


  17. 317
    Walter Pearce says:

    Regarding methane, here’s an op-ed from a reliable source who puts numbers to methane leaks from fracking:

    “But recent measurements by the National Oceanic and Atmospheric Administration at gas and oil fields in California, Colorado and Utah found leakage rates of 2.3 percent to 17 percent of annual production…A 2011 study from the National Center for Atmospheric Research concluded that unless leaks can be kept below 2 percent, gas lacks any climate advantage over coal.”

    Apologies if this has already been mentioned here recently.

  18. 318

    #316–That’s easy, Chuck. We are seeing rates of roughly 2 ppm–which is, I think, what you meant to type for “ppb”–each year. So if that rate were to continue, we should see (in Ralph Keeling’s words*) the first “flicker” of 450 ppm just 25 years from now–2038. We’d then hit 500–the previous benchmark you mentioned in an earlier comment–in a further 25 years, which would be 2063.

    Of course, that’s just extrapolation. Three monkey wrenches:

    1) Emissions still seem to be increasing globally.
    2) It’s unknown (AFAIK) how long CO2 sinks will continue to operate at their current efficacy, and there are good physical reasons to suppose that at some point that efficacy will decrease. That would of course increase atmospheric concentrations more quickly.
    3) As warming continues, we may see natural sources–as, for instance, the methane releases which we have been discussing at some length increase, and it’s possible that these may be highly non-linear. (Again, see methane discussion.)

    On the other hand, emissions mitigation may yet occur, and may occur in a non-linear fashion as well.

  19. 319

    Oh, I forgot the asterisk in the comment above. Old-fashioned footnote format; I wanted to point to the article I wrote on attaining 400 ppm earlier this year, which included the ‘first flicker’ comments of Ralph Keeling.

    The piece may still be of some interest to those who haven’t had occasion to look into CO2 monitoring, the Keeling curve, et cetera.

    Also good to point to when someone mentions the ‘puny humans’ meme! ;-)

  20. 320
    Omar Cabrera says:

    @314 @312 Actually, it started in Feb. 4th. and it’s still going today ( IASI has been getting high readings twice every day (at the 0-12z and 12-24z satellite passes) for almost 6 months without signs of stopping. As the southern winter sets in, the emissions seem to be lower, but everything you see in yellow in the link above is methane over 1950ppb today. It goes from 440hPa to 640hPa and it usually shows the most at 586hPa. What I wonder is how these graphs are going to look like in summer in few months more.

    Methane mixes well in the atmosphere. What I have observed for sources where we know the duration (like wildfires), is that high remote readings almost never last more than 24 hours before they go down (meaning, before the methane mixes with the atmosphere).

    Now, I don’t know if methane mixes well in Antarctica’s weather. One would guess that it’s unlikely for methane to remain in the atmosphere for 6 months when it normally dilutes within 24 hours (also, when you look at the animation overtime, it does look like new methane is being generated inland and old one blown out to the coast).

    Where is it generated? We don’t know. If I have to give a wild guess without scientific backup, IF the same methane mixing applies in Antarctica than what observed in Siberia (which I don’t know); just eyeballing it looks like it’s coming from a unique source but vented from many areas (40 to 100 maybe?) I could write a program to count them, identify 65 mile radius “hotspots” and measure how much methane is going out from those hotspots (this, if I knew how methane behaves in the Antarctic weather at those hPa and the remote readings exact margin of error in Antarctica).

    Thing is, I don’t want to do this and add to more confusion. I insist that the best way to go about this is to get ready now and send an aircraft beginning of Summer to measure the methane right there in East Antarctica. This will eliminate all errors and assumptions and will also serve as a good tool to validate remote readings in Antarctica.

    PLEASE NOTE that a methane venting episode coming from East Antarctica is crazy, illogical, unexpected and it should not be happening. It’s like watching pink elephants flying by your window. First I think we need aircraft measurements and field research to validate this beyond any doubt. If there is methane in East Antarctica, we must understand this as another positive feedback, and try to make sense of it as to include it in future computer models.

    In regards to Dr. Yurganov’s comment about AIRS, if Yurganov says it’s 4th of July, I grab the firecrackers and start my grill without question. Yet AIRS is a different instrument than IASI. I’ll ask him his thoughts about IASI.

  21. 321
    Mal Adapted says:

    David B. Benson, in response to Dave123:

    As for your first question AFAIK the codes do not use pseudo-random number generators. It is typical to repeat runs using slightly different initial conditions to establish variation.

    It sounds like Dave123 is asking about Monte Carlo simulation, where a (pseudo-)random number generator is used to vary the initial conditions.

  22. 322
  23. 323
    Susan Anderson says:

    @309 (climatestate)


  24. 324
    prokaryotes says:

    @320 Omar, i was just reading this study paper abstract

    Identification and control of subglacial water networks under Dome A, Antarctica
    “Subglacial water in continental Antarctica forms by melting of basal ice due to geothermal or frictional heating

    The water system in the Gamburtsev Subglacial Mountains reoccupies a system of alpine overdeepenings created by valley glaciers in the early growth phase of the East Antarctic Ice Sheet. The networks follow valley floors either uphill or downhill depending on the gradient of the ice sheet surface. In cases where the networks follow valley floors uphill they terminate in or near plumes of freeze-on ice, indicating source to sink transport within the basal hydrologic system. Because the ice surface determines drainage direction within the bed-constrained network, the system is bed-routed but surface-directed.”

    Not sure if i understand this correctly but maybe basal melt and following uphill drainage is transporting melted methane hydrates to the surface?

    recaptcha = uagemli rises

  25. 325
  26. 326
    Hank Roberts says:
    Future Climate Change
    Many good links on the page supporting the statements made.
    Good presentation, I think.

  27. 327
    Hank Roberts says:
    Asian monsoon precipitation changes and the Holocene methane anomaly
    December 14, 2011, doi: 10.1177/0959683611430408
    The Holocene July 2012 vol. 22 no. 7 731-738

    “we conclude that the late-Holocene methane increase has been significantly influenced by the expansion of early rice paddy fields during the period of declining monsoon precipitation.”

  28. 328
    Tony Weddle says:

    The rate of CO2 increase has itself been increasing. So I would expect 450ppm to be reached much earlier than 2038. But the CO2 mark is not mystical and not even the target of the 2 degree policy; that mark is 450ppm of CO2 equivalent. It’s hard to find any on-going measurement of that figure but I’m convinced (currently) that the influence of methane needs to be increased in calculations. It’s concentration is rising and so the short term impact of the concentration (1850ppb or more) needs to be used, instead of the long term impact. What is the CO2-e number now? From earlier calculations I’ve seen, it roughly keeps up with the CO2 number. Aerosols are the primary negative forcing, which keeps the CO2-e number down. An economic crash or a peak in fossil fuels burning would likely bring the aerosols figure down rapidly, and the CO2-e number would, correspondingly, shoot up. If methane feedbacks come into play more, there could be some fireworks in the not too distant future.

    I’ve heard a number of climate scientists pretty much state that keeping within 2 degrees is now out of reach. I just wish that such a position was more openly stated because our so-called political leaders can keep procrastinating if they think the public thinks that we’ve still got decades before 450ppm is reached and, therefore, still have time to do something about it. 2 degrees is now unstoppable, so we need a different target, a different strategy.

  29. 329
    sidd says:

    “… maybe basal melt and following uphill drainage is transporting melted methane hydrates to the surface …”

    Now, that’s a thought. Let’s say hotter water flowing between ice and rock hits a patch of clathrate. Water freezes dumping latent heat into methane release. Methane squirms out as best as it can, will not reform clathrate because as it rises it is out of the pressure boundary on clathrate stability zone. Density difference between methane (even at pressure and either water or ice is huge, buoyant force prevails, methane escapes into air.


  30. 330
    Dave123 says:

    @ David Benson and @ Mal adapted-

    The Abstract of Hong notes “The system dependency, which is the standard deviation of the 500-hPa geopotential height averaged over the globe, increases with time. However, its fractional tendency, which is the change of the standard deviation relative to the value itself, remains nearly zero with time. In a seasonal prediction framework, the ensemble spread due to the differences in software system is comparable to the ensemble spread due to the differences in initial conditions that is used for the traditional ensemble forecasting.”

    The problem is that I have no idea what the significance is for the system dependency increasing with time, while the fractional tendency remains nearly zero means. And since it’s paywalled, I’m not going to find out unless someone here knows…since this is my only access to the modeling community.

    On that note, the July 19th issue of Science has two letters to the editor about validation, verification and uncertainty quantification (VVUT) for complex modeling and publication, and it would be interesting to understand where climate models stand with this compared to many other complex modeling systems.

    And no, I wasn’t really talking about Monte Carlo in this case, although I can see how you might think so. What i was getting as was some nudges to the system because we can’t to my knowledge predict ENSO and other cycles, or volcanic eruptions…so whatever is in there is moved around a bit to see if it produces some amplified effect, or whether it’s damped.

  31. 331
    Russell says:

    It seems Yamal affords other subjects for controversy besides trees- this just out in GRL:

    Offshore permafrost decay and massive seabed methane escape in water
    depths >20 m at the South Kara Sea shelf†

    Alexey Portnov1,3,*, Andrew J. Smith1,3, Jürgen Mienert1,3, Georgy
    Cherkashov2,3, Pavel Rekant2,3, Peter Semenov2,3, Pavel Serov2,3,
    Boris Vanshtein2,3
    DOI: 10.1002/grl.50735


    [1] Since the Last Glacial Maximum (~19 ka), coastal inundation from
    sea-level rise has been thawing thick subsea permafrost across the
    Arctic. Although subsea permafrost has been mapped on several Arctic continental shelves, permafrost distribution in the South Kara Sea and the extent to which it is acting as an impermeable seal to seabed methane escape remains poorly understood.

    Here we use >1300 km of high-resolution seismic (HRS) data to map hydroacoustic anomalies, interpreted to record seabed gas release, on the West Yamal shelf.

    Gas flares are widespread over an area of at least 7,500 km2 in water depths >20 m. We propose that continuous subsea permafrost extends to water depths of ~20 m offshore and creates a seal through which gas cannot migrate. This Arctic shelf region where seafloor gas release is widespread suggests that permafrost has degraded more significantly than previously thought.

  32. 332
    Marc Opie says:

    Brian Lilley, (Fox News North, aka Sun Media), has made the claim numerous times that there has been no global warming in twenty years. Any truth to this?

    I’ve been trying to find temperature data, for the globe, on a year by year basis, to examine the claim.

  33. 333
    Ray Ladbury says:

    Marc Opie,
    It is a bald-faced, flat-out lie.

  34. 334
    Hank Roberts says:

    Also for Marc Opie:
    Page down to where he tells you
    “Depending on your preconceptions, by picking your start and end times carefully, you can now ‘prove’ that:
    Temperature is falling!
    Temperature is static!
    Temperature is rising!
    Temperature is rising really fast!”
    with clickable links to examples.

    That’s how to fool others (or yourself, or both) who don’t understand the basic lesson from Statistics 101 — given a data set, how to figure out (it’s arithmetic, not opinion) how many data points (years, for “annual” numbers) are needed to make a statement about it.

    You’re asking how to say with confidence that a trend does or doesn’t exist in that particular data set.

  35. 335
    Chuck Hughes says:

    If the increase of CO2 is at a rate of roughly 2 ppm per year, do we know how much of that increase is due to methane escaping from the permafrost and how much is directly related to human activity? I assume the methane levels will increase over time and add to the CO2 problem.

    Also, Thank you to Kevin and Ray L. for responding to my questions. I try to ask questions that I think the average person would ask and I appreciate your patience.

    It would be nice to have some polling data on the optimism of Climate Scientists overall. I would love to know how many have a sunny outlook about our situation and if so, why?

  36. 336
    Hank Roberts says:
    Signature of ocean warming in global fisheries catch
    Nature 497, 365–368 (16 May 2013)

    “… (increasing dominance of warm-water species)…. a signature of such climate-change effects on global fisheries catch …. we report such an index, the mean temperature of the catch (MTC), that is calculated from the average inferred temperature preference of exploited species weighted by their annual catch. Our results show that, after accounting for the effects of fishing and large-scale oceanographic variability, global MTC increased at a rate of 0.19 degrees Celsius per decade between 1970 and 2006, and non-tropical MTC increased at a rate of 0.23 degrees Celsius per decade….”

  37. 337

    #332–Yes, that claim is completely absurd, totally false, even–gasp!–wrong.

    As to data sources, here is an overview.

    There are three ‘thermometer-based’ records which are frequently cited, GISTEMP (a product of NASA’s Goddard Institute for Space Studies), the (US) National Climate Data Center, and UK’s Hadley Center/Climate Research Unit data.

    First, the GISTEMP data:

    There are different versions; that’s Land and Ocean (LOTI) monthly global anomalies. (The yearly anomaly is also included, as are seasonal anomalies.) “Anomaly,” by the way, refers to the fact that the numbers are given not in absolute temperatures such as we encounter in daily life, but rather as differences from a given ‘baseline period’ mean temperature. For GISTEMP, that’s 1951-1980.

    The whole idea of anomaly is also explained well on the NCDC ‘Global Surface Temperature Anomalies FAQ’ page:

    From there you can find the monthly data, similar to GISTEMP:

    The remaining dataset of the instrumental (basically thermometric) Big Three is the British data, referred to infomally as HadCRUt:

    It shows a little less warming than the other two, because it basically ignores a fairish chunk of the Arctic, which of course is the quickest-warming portion of the planet (though this issue has been partially addressed in the most recent version, HadCRUt 4.)

    Satellite-based remote sensing of atmospheric temperatures is also often cited. This has different characteristics from the instrumental record; the latter is based on temperatures at 2 meters (for land, though not for sea), while the satellite records are really responding to a much greater depth of the atmosphere. In practice, that means (among other things) that they show a lot more volatility to weather–especially the famous El Nino/La Nina cycles known as ENSO.

    Anyway, the two satellite datasets are RSS (Remote Sensing Systems) and UAH (University of Alabama Huntsville.)

    Their data can be found at these sites:


    RSS overview:

    Just to complicate things further, both UAH and RSS data are further processed by a team at the University of Washington to create two further products, known as RSS-UW and UAH-UW. (The purpose of this processing is to minimize contamination of tropospheric temperature by the stratospheric influence, if I remember correctly.)

    Many of these datasets can be ‘played with’ at the woodfortrees site that Ray linked. It’s a great and mostly fun (but sometimes frustrating) way to get a feel for the data.

    To conclude this lengthy comment, a convenient way of assessing the idea that Mr. Lilley has put forward is to use a statistical procedure that pretty much everybody understands: averaging. Compile the yearly anomalies for each of the last several decades and average them (Excel is readily available for this, or doing by hand is not unfeasible.) You’ll find that the 80s were the warmest decade in the record–until the 90s, when the 90s took the title. But that only lasted until the 00s were in the books. See a pattern emerging? I haven’t calculated averages for the current decade so far, yet. But I’d guess that it’s about comparable to the 00s.

    Do that exercise for yourself, and you, too, will be able to say with authority that Mr. Lilley is full of ‘Shinola.’ (Literally, an archaic shoe product, I believe, but I trust the metaphoric import is clear enough.)

  38. 338

    Oh, and Marc, should you lose this response (or just find it a bit much–understandable!) you can always find climate data by going to Tamino’s blog, Open Mind:

    If you look up in the masthead, there’s this clickable link that says “Climate Data Links.” Handy, that–though I did my above comment strictly by Googling.

  39. 339
    Dan Lufkin says:

    @330 — Dave123
    What the Hong paper boils down to is that there’s no systematic difference introduced by running the usual dynamic models under different computer operating systems and different hardware. There are slight variations, probably from rounding-error effects, but the results agree quite well. Over longer forecast periods, a key measure of variation (the 500-millibar height) becomes more variable, but the percentage error does not change significantly.

    The reference to “ensemble forecasts” is about a common procedure of running a model with slightly varying inputs and comparing the different forecasts that result. (Wikipedia has a good treatment, not too technical.) Or you can run different models with the same inputs. You’ll often see this approach in hurricane forecasting. You feed today’s observations into a half-dozen different models and plot all the forecast tracks together. (The spaghetti approach.) Usually, the best forecast will be the one that agrees with the most tracks. Sometimes, only one of the models gets it right (Sandy, for instance, and the European Forecast Center model.) Then everybody learns something.

  40. 340

    #335–”If the increase of CO2 is at a rate of roughly 2 ppm per year, do we know how much of that increase is due to methane escaping from the permafrost and how much is directly related to human activity? ”

    Precious little is due to methane. Consider that these locally high methane concentrations we’ve been talking about–1900 PPB or so–are less than the yearly atmosphere-wide CO2 increase. (Ie., 1900 PPB = 1.9 PPM.) Global methane is lower than that, and since methane lifetime in the atmosphere is about 10 years, only a fraction of *that* would be ‘new methane.’

    But you could search up a more detailed answer–sinks and sources of CO2 and methane have certainly been studied, so I’m sure that numbers are available.

  41. 341
    Hank Roberts says:

    Chuck Hughes asks about methane. Google Scholar is a good place to start, look for review articles from the last year or three, for example:

    It’s science writing, focusing more on what we don’t yet know and how we could find out than on what we do know so far.

  42. 342
    Hank Roberts says:

    Brief quote from that _copernicus.org_ paper:

    “Here we show a synthesis of the global CH4 budget for the past three decades by consolidating the available knowledge from the above approaches: atmospheric inversions, bottom-up land surface models, and emission inventories. With support from the Global Carbon Project, we have been bringing together most of the scientific teams working on estimating CH4 sources and sinks from regional to global scales. We will present a complete synthesis of the decadal CH4 budget for the past three decades, the regional CH4 budget, the interannual variability of atmospheric CH4, and the remaining uncertainties in the knowledge of the CH4 cycle.”

  43. 343
    prokaryotes says:

    Arctic methane catastrophe scenario is based on new empirical observations
    Critics of new Nature paper on costs of Arctic warming ignore latest science on permafrost methane at everyone’s peril

    I would rather see a discussion based on probability than credibility. And a discussion which includes all greenhouse gas sources, ie. methane hydrates from ocean seabed deposits, permafrost thaw, soil respiration, wildfire feedbacks in higher latitudes, pipeline leakage (which is increased through permafrost melt), thermokarst formation, carbon river discharge providing material for decomposition…

    DOC is a food supplement, supporting growth of microorganisms and plays an important role in the global carbon cycle through the microbial loop. Moreover it is an indicator of organic loadings in streams, as well as supporting terrestrial processing (e.g., within soil, forests, and wetlands) of organic matter. Dissolved organic carbon has a high proportion of biodegradable dissolved organic carbon (BDOC) in first order streams compared to higher order streams. [..] The BDOC fraction consists of organic molecules that heterotrophic bacteria can use as a source of energy and carbon. BDOC can contribute to undesirable biological regrowth within water distribution systems.

    They release energy by oxidizing carbon and hydrogen atoms present in carbohydrates, lipids, and proteins to carbon dioxide and water, respectively. Most opisthokonts and prokaryotes are heterotrophic.

    Another important point is to acknowledge better the latitude characteristic of today’s cryospheric setup and that this unique scenario is different from past deglaciation patterns, hence different feedback potential in time and space.

  44. 344
    Hank Roberts says:

    They just don’t give up, do they? The Grauniad

    – cites its own 2010 article as “the latest science”
    – conflates methane hydrates and carbon permafrost sources
    – loses the facts about what’s warming where
    – obscures the issues of probability
    (one is improbable, the other is observed fact)
    – captures More Credulous Readers Fast

    Their advertisers must be thrilled.

    What’s really amazing is that a couple of years ago it was methane hydrates all the time, seabed bubbles, vast plumes in the water — and the scientists pointed out that, no, they’re detecting known sources of recent carbon from permafrost melting — a real, known, observation — and said there’s nothing in the past suggesting the seabed warms up that much that fast.

    And here we are three years later, and the methane drumbeat story is taking the facts the scientists raised — that it’s known to be coming from permafrost, and nobody’s yet published a picture or description of the Laptev Sea bubbling as described back then; the same news story keeps being reblogged as though it’s news. And the methane from permafrost? Yeah we know that. The disintegrating permafrost putting organic carbon into the rivers that flow out to sea where it too gets oxidized? We know that.

    Pull the damn methane hydrate rabbit out of the hat or quit waving that hat in our faces, huh? Whoever’s hyping this methane confusion is capturing the attention of some deeply sincere, highly concerned, very motivated people — so they spend time, effort and worry about the wrong problems.

    Polarizing the opposition is a great classic old denial tactic
    Fund the extreme edges of the policy area.
    Set them against each other.
    Delay and profit.

    Reality is plenty scary enough.

    Yes, the evidence for methane will bubble up eventually, given time.

    It will hardly matter by the time it does, because
    What matters is stopping burning fossil fuel, now.

    It makes no practical difference whether or not we get to the point methane erupts from the seabed — as it’s never done before, in those areas, even when the polar ice melted away completely in the deep geological past, so we can’t show that it’s at all probable it’ll happen anytime soon.

    It makes no practical difference because _we_don’t_want_to_go_that_direction
    and all the steps
    all the steps in that direction
    involve burning more coal and oil
    digging more coal
    drilling more oil

    Stop doing the stupid, and the incredibly stupid won’t be reached.

    Get everyone worried about the incredibly stupid,
    while doing the stupid
    drilling for gas
    and claiming it’s helping the climate problem
    and we’ll end up where we’re headed now.

    Do we really want to do this?

  45. 345

    #343–Thanks for the link. The ‘money quote’ is perhaps this one:

    The mechanism which is causing the observed mass of rising methane plumes in the East Siberian Sea is itself unprecedented and hence it is not surprising that various climate scientists, none of them Arctic spec-ialists, failed to spot it. What is actually happening is that the summer sea ice now retreats so far, and for so long each summer, that there is a substantial ice-free season over the Siberian shelf, sufficient for solar irradiance to warm the surface water by a significant amount – up to 7C according to satellite data.

    That warming extends the 50 m or so to the seabed because we are dealing with only a polar surface water layer here (over the shelves the Arctic Ocean structure is one-layer rather than three layers) and the surface warming is mixed down by wave-induced mixing because the extensive open water permits large fetches.

    So long as some ice persisted on the shelf, the water mass was held to about 0C in summer because any further heat content in the water column was used for melting the ice underside. But once the ice disappears, as it has done, the temperature of the water can rise significantly, and the heat content reaching the seabed can melt the frozen sediments at a rate that was never before possible. The authors who so confidently dismiss the idea of extensive methane release are simply not aware of the new mechanism that is causing it.

    That’s Dr. Peter Wadhams, defending the plausibility of the idea that current conditions could cause just such a methane release as is envisioned in his recent paper with the economic modelers–you remember, the one which attached the $60 trillion price tag to sea ice loss. If he’s right, we’re seeing the early development of a serious non-linearity–a ‘tipping point.’

    True, there remains the point that it’s less significant for the long-term trajectory than one might think–a point that was also evident in the ‘Wadham paper’ (Whiteman et al, 2013)–as Gavin and Dr. Archer have pointed out. But the price tag remains, and so does the fact–presuming it to be fact for the moment–that the ride is going to get a lot bumpier for all of us over the next couple of decades.

    The trouble, of course, is that if Dr. Wadhams is right in this suggestion, then clearly we can’t mitigate our way out of this particular consequence anymore. (And probably not out of more or less complete loss of the Arctic sea ice–though I’ve been pretty pessimistic on that score for a while, as a lot of observers have.) The best ‘action points’ that can be taken from it are adaptive–we can plan for the probable consequences.

    If Whitehead et al was correct, that means that the developing world is going to be hit very hard indeed. What to do about that? Obviously a very, very large question!

    Perhaps needless to say, that doesn’t mean that mitigation is a dead letter–there could be further non-linearities that we can still avoid if we stop being so infernally self-defeating…

  46. 346
    Hank Roberts says:

    Sorry that got so wordy.


    Scientists are skeptics. Emulate that. When you read news, follow the link, look at the date and source; find the science cited. If you see a blog — look for a contact link on the page; ask the person named as contact for the actual facts behind the claim, and the date and source of the facts.

    If it’s from 2010, it’s not news.

    If you passionately believe it must be true — double check.
    If you’re funded — ask who you’re being funded by.

    Here’s how the delay-by-funding-opposites trick works. It’s an old one.
    With enough money, fund an argument, hollow out the policy center by building more political action around the edges and let’em fight:

  47. 347
    Hank Roberts says:

    OK, Gavin’s engaged with the Guardian writer Nafeez Ahmed, on Twitter, now. Go there for the interesting stuff:

  48. 348
    David B. Benson says:

    Dave123 @330 — Oh, I now understand. ENSO might well use an AR(2) process with a random number generator and I forgot about volcanoes as well.

  49. 349
    David B. Benson says:

    Polar Ecosystems Acutely Vulnerable to Sunlight-Driven Tipping Points
    Reduced biodiversity in the Southern Ocean

  50. 350
    David B. Benson says:

    Could Planting Trees in the Desert Mitigate Climate Change?
    This group suggests planting Jatropha curcas unlike
    Irrigated afforestation of the Sahara and Australian Outback to end global warming
    where a large eucalyptus is suggested.

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