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Good climate debate FAQ

Filed under: — group @ 13 March 2006

There are a number of topics in climate science that are frequently misunderstood or mis-characterised (often by those trying to ‘scientize’ their political opinions) that come up again and again in climate-related discussions. RealClimate tries to provide context on many of these issues, and commentaries on the 1970s ‘global cooling myth‘ or whether water vapour is a feedback or a forcing are among our most referenced pieces (see our FAQ category). However, our explanations of specific points have often appeared in the middle of a larger piece, or in the comment section and are not clearly referencable. Since many of these same points keep coming up in comments and discussions, having a clear and precise resource for these explanations would be very useful and we have thought about doing just that. But it now appears that we have been beaten to the punch by a new blog run by Coby Beck, a frequent commenter here and at sci.env. His new blog ‘A few things ill-considered‘ has a point-by-point rebuttal of almost all the most common ‘contrarian’ talking points. The list of topics by category is a good place to start, and it shows the huge amount of work done so far. We’re very impressed!

87 Responses to “Good climate debate FAQ”

  1. 51
    Charlie T says:

    I watched the BBC Meltdown program last night and it demonstrated how climate models match past climate, quite nicely.
    If it does turn out that the MWP was more widespread than we currently consider, I presume that the climate models parameters could be adjusted to accommodate that information.
    I was wondering whether the adjustments for, say, a MWP as warm as today would impact on the estimates of the climate sensitivity to CO2?

    [I suspect there are loads of things ill-understood within this question!]

    [Response: Let’s suppose that some brand new data-set proved definitively that the MWP was globally as warm as today. What would that imply for climate sensitivity or climate modelling? Nothing. The reason is that sensitivity is made of two components – the forcing and the response. Unless the forcing terms could be similarly tightly constrained (particularly solar and volcanic), there will always be a wide error bar on any climate sensitivity derived from the MWP. Those error bars currently easily encompass the range of sensitivities shown by current models, and so do not cause any inconsistency. As an aside, although constraining climate models using paleo-data is often talked about, as a practical matter it never happens – the evaluation of climate model parameterisations is done on the much better observed present day data. Paleo-climate modelling is much more useful as a way of testing hypotheses about what caused previous changes, and validating the model in the meantime – see this recent example. -gavin]

    [Response: Gavin, if I may contradict you on one point: climate sensitivity in climate models is being constrained with paleo data. But not with the MWP but with the Last Glacial Maximum, see the study by our PhD student Thomas Schneider von Deimling (in press with Climate Dynamics). The Last Glacial Maximum also has a lot of data uncertainty, but the signal is much larger, so that you do get a useable signal/noise ratio there. -Stefan]

    [Response: Adding in my own two cents, it remains difficult to produce hemispheric-scale medieval warmth comparable to that of the late 20th century using anything but a rather extreme and improbable scenario of extremely high solar irradiance, that is unsupported by any existing reconstruction of solar variability over the past millennium. So, in practice, some contraints are provided by paleo measurements over the past millennium, arguably even more so if one uses the dual constraints of surface temperature and pre-anthropogenic co2 variation in the context of a coupled climate/carbon cycle model as in Gerber et al (2003). -mike]

  2. 52
    Hank Roberts says:

    Armin — yes, I am confused about whether there’s a difference between “polar stratospheric” and “noctilucent” clouds — other than how far from the poles they are being observed. Both are stratospheric; both are noctilucent (high enough the sun lights them up long after sunset); some appear farther south and others don’t. I thought from what I’ve read that the only difference is location where observed, and that the difference in naming is because they have been observed farther from the poles in the last century or two. But I’d welcome more info or a pointer from anyone.

  3. 53
    Dragons flight says:

    Re 52: The term “noctilucent clouds” is generally intended to mean mesospheric clouds, not stratospheric.

  4. 54

    Re #51 (Stefan’s comment)

    Stefan, is there a (pre)view of that article possible?
    If on uses the LGM-Holocene transition, it seems to me that it is possible to have a general climate sensitivity for all actors and feedbacks together, but quite impossible to make a differentiation in sensitivities for insolation/latitude changes, ice and vegetation feedback and CO2/CH4 feedback/forcing during the transition, as these all overlap in the transition period…

    And I suppose that the Holocene sensitivity is not necessary the same as the LGM-Holocene sensitivity , as the ice albedo/vegetation feedback is much less now, for the same initial forcing.

    [Response: Ferdinand, two good points to ask.
    The study is based on a large ensemble of model simulations (1,000), in order to vary the key uncertain parameters, and it uses all forcings including ice sheet, vegetation, dust load and insolation changes in addition to CO2. With all of these model versions, both the Last Glacial Maximum climate and a CO2-doubling climate are computed. The latter gives you the sensitivity to CO2 doubling, of course – and here it is not assumed that this is the same for glacial climate and Holocene, that is one of the strengths of this approach. With all of these model versions, you get a different climate of the Last Glacial Maximum – only some of which pass muster when compared with the actual data from this time. You throw out all other models as unrealistic. Put simply, because CO2 lowering does play an important role for glacial climate (next to all the other forcings), if you have a model with an unrealistically great sensitivity to CO2, then your glacial climate is going to be too cold.. We found that all of the model versions with a climate sensitity greater than 4.3 ºC failed the test with the glacial climate data (considering also uncertainty in forcing and paleo data), hence we conclude that climate sensitivity is unlikely to be greater than 4.3 ºC. For details, wait for the paper – should be out shortly in Climate Dynamics, we’ve already had the proofs. -Stefan]

  5. 55
    Coby says:

    Dragon’s Flight,

    Another request: atmospheric CO2 levels for the entire holocene, perhaps shorter, I leave that to your brilliant artistic eye, but longer the better for illustrating the balance we have upset.

  6. 56
    Armin says:

    Re #52, #53

    Hank, there is fundamental difference between noctilucent clouds (NLC) and polar stratospheric clouds (PSC).

    NLC occur in the summer mesopause region at around 83km. They are thought to be made of water ice which may be polluted by some dust or metals from meteoric ablation. Although there is very little water vapour at these heights, the polar summer mesopause temperatures are low enough (typically 130K) to allow particle formation. There are some nice pictures and explanations here. Outside the summer season, the mesopause region is too warm for NLC formation.

    NLC are usually observed polewards of 60° latitude but they have been seen occasionally further equatorwards. Three have been a few sightings even in Utah (40N). See e.g. Taylor et al. 2002. NLC occurrence frequency shows a correlation to the 11-year solar cycle. Some years ago, there was some discussion of an increase in NLC but this has been laid to rest with longer data sets becoming available. M. Gadsen has done a lot of work on this and Google Scholar will help you find the papers.

    PSC occur in the stratosphere roughly between 15-30km in winter. They can consist of water ice, sulphuric acid droplets or nitric acid tri-hydrate. Depending on temperature, a specific cloud can consist of one of these or a combination of these. They are sometimes also called mother-of-pearl clouds because they can display beautiful colours.

    PSC are involved in the destruction of the ozone layer via heterogeneous chemistry on the surface of the PSC particles and de-nitrification. When it gets colder than the threshold for PSC formation (roughly 195K) not only do these beautiful clouds form but also ozone destruction is enhanced.

    Hope this clears up the difference between noctilucent clouds and polar stratospheric clouds. If you need more info, you can email me privately.

  7. 57
    Hank Roberts says:

    Thank you, that’s very helpful.

  8. 58
    Mikel Marinelarena says:

    Re #27 It’s very interesting to see how often Lomborg is criticised on this website. In fact, Lomborg has repeatedly declared that he believes that global warming is happening and that it is human caused. His only discrepancies are related to the prevalent policies advocated to mitigate it. But this website is not about public policies but just about climate science.

    I wonder what this constant criticism of Lomborg on this website reveals. Most probably that many AGW-thesis enthusiasts have an environmentalist bias (Lomborg does criticize the alleged science behind other environmental issues). Hopefully not an ideological bias of that kind among contributors and mainstream climate scientists.

    [Response: Read the GW chapter of TSE. Its full of nit-picks, many of which (like the MSU stuff) have turned out to be wrong – William]

  9. 59
    Timothy says:

    Interestingly, there seems to be some disagreement between the climate model response to the 1883 Krakatoa eruption [very noticeable] and the observed global temperature record [somewhat of a damp squib]. This suggests one of three [four?] possibilities [or a combination thereof]:

    1. The climate models are over-sensitive to the volcanic aerosol forcing.
    a. Because they are over sensitive to aerosols [ie the model is wrong and the obs are right]
    b. Because they are over sensitive to radiative forcing more generally. [ie the model is wrong and the obs are right and climate sensitivity is lower than the models suggest]

    2. The temperature reconstruction is faulty. [ie the model is right and the obs are wrong]

    3. The [volcano aerosol] forcing reconstruction is faulty. [ie the model and the obs may both be right]

    In fact the main discrepancy seems to be with the sea surface temperature [SST] response, the land surface response is quite good. This discrepancy is that the obs don’t have a Krakatoa-induced dip, whereas the models do.

    Interestingly, this difference appears to be reversed for a dip in the SST obs around 1910, when the model ocean doesn’t show a large response. I note that this appears to be correlated with a volcanic eruption where Sato et al and Robauck & Free disagree on the radiative forcing of the volcano, so this later discrepancy may depend on the dataset used for the volcanoe forcing in the model.

    However, the main point is that the [negative] forcing from volcanic eruptions is shortlived [a few years at most] since the aerosols eventually get rained out, whereas the forcing from CO2 is long-lived because the CO2 accumulates in the atmosphere.

    [Response: Well spotted! This discrepency has been investigated by us in the Hansen et al (submitted) paper looking at the transient runs. Check out Fig 7/section 4.2 (p11). Basically, while there is some uncertainty in the size of the forcing (which could play a role), a more likely reason is that the ocean temperature reconstructions fail to capture the strength of the cooling. If the comparison of the model is just done over land where there are station data, than (although the record is a little noisier) the match to the model is much better. The comparison for Pinatubo shows that the models are appropriately sensitive to volcanic aerosols, and the land station match implies that the aersosol forcing is not that far off. – gavin]

  10. 60
    Mikel Marinelarena says:

    Re #58 Leaving nitpicks aside, Lomborg actually declares himself a supporter of AGW. But even if he weren’t, I had understood that ad-hominems such as the one in post 27 were not welcome on this website.

    By the way, I’m still waiting for my reply to Hank Roberts in to be published. 2 days already and counting. I had to submit previous posts several times before they could eventually see the light. Are my moderately sceptical opinions being censored??

    If so, could you be so kind and let me know, so that I stop wasting my time composing them?

    Many thanks in advance.

    [Response: Do you consider it “censorship” when a newspaper declines publication of Letters to the Editor that are deemed irrelevant, repetitive or just uninteresting? In order to keep the discussions more on-target and avoid repetition of positions that have been aired amply before, we have indeed decided to be a little more aggressive in moderating the comments. In doing this moderation, it does seem to me that a disproportionate share of comments I’ve deleted on the grounds of repetitiveness, inflammatoriness, dullness or just plain wrongness have been from the skeptical side. I don’t think that reflects any prejudice on my part, but more the general impoverishment of scientifically credible ideas on the part of the skeptics. As for post 27 on Lomborg, I don’t see anything the least ad hominem about it. It is very common for that community to declare that there are more pressing things to spend money on than avoiding global warming, but when that argument never gets translated into action on such self-declared priorities, one begins, quite legitimately, to suspect that it’s just a ruse or delaying tactic. To put it another way, if those who declare we should be spending on clean water instead in fact fail to make any successful arguments resulting in more spending on clean water, one has to suspect that their arguments for clean water vs. global warming are not so convincing after all. To be sure, one should look at the arguments themselves, but if the proponents of such action fail to act, that’s valid data. –raypierre]

  11. 61
    Doug Percival says:

    Here’s another new resource that may be useful and I think answers a need that has been mentioned here before for a concise summary of recent climate change science: the World Resources Institute has published a 14-page “issue brief” entitled “Climate science 2005: Major new discoveries“. It is available from the WRI website in PDF format, and the content is also available as web pages on the WRI site:

    Here’s an overview from the WRI site:

    2005 was a year in which the scientific discoveries and new research on climate change confirmed the fears and concerns of the science community. The findings reported in the peer-reviewed journals last year point to an unavoidable conclusion: The physical consequences of climate change are no longer theoretical; they are real, they are here, and they can be quantified.

    In this short paper, WRI reviews some of the major discoveries from the past year. Taken collectively, they suggest that the world may well have moved past a key physical tipping point.

    In addition, the science tells us the effects of climate change are at a scale that adds enormous urgency not only to the efforts to prevent additional change, but equally important, to efforts to adapt to the impacts already occurring.

    Finally, the science makes it clear that additional climate impacts will result even if emissions of greenhouse gases are halted immediately.

    A wide body of scientific and technical literature was reviewed in the preparation of this paper, including key general science journals (Nature and Science), several technical journals (Geophysical Research Letters, Annals of the Missouri Botanical Gardens, Ecology Letters, Ecology, Environment International, and Journal of Climate) and material from key web sites and international organizations (, the UN’s Food and Agriculture Organization, the U.S. Department of Energy, and others).

    Each scientific paper is briefly described, along with the full citation to the original paper, and a short comment regarding the implications of each discovery is offered.

  12. 62
    Mikel Marinelarena says:

    [Response: … Irrelevant stuff deleted –raypierre]

    With all that being the case, you do not have to worry about my posting here any more. Even though one would expect a great improvement from now on, with NO more comments being repetitive, irrelevant, uninteresting, inflammatory, dull or just plain wrong :-)

    [Response: I can’t promise that moderation will be 100% effective at achieving the goals of making the discussion more informative, nor can I promise that it will never be the case that a comment gets unfairly deleted. Nonetheless, it is hoped that a little more active moderation will improve the quality of discussion. –raypierre]

  13. 63
    Matt says:

    I looked at the blog: “A few things ill-considered” and objected right away with this:

    “But in the natural process, every tonne of carbon going into the atmosphere is balanced by one coming out. What we have done is to alter only one side of this balance, we put CO2 into the air but, unlike nature, we are not taking it out. ”

    Which is absolute nonesense. If nature was perfectly balanced there would be no glacial cycle. Right now, nature, in the absence of man, would be spewing out net carbon, don’t need to look beyond the previous glacial cycles to see this obvious point. Peat burns during dry interglacial periods, forests burn, soil oxidize, tundra unfreezes, natural coal burns. I would be suprised if the Canadian tar sands have not burned in the past.

    And man takes out a lot of carbon. Man is a squirrel, after all, he uses carbon energy on the margins. We never hear much about the carbon man takes out because all the climatologists are having a bonanza on the well measured carbon we are putting in. More research carbon research will balance this falshood.

    And my final point, of course we manage a lot of the fluxes, we are the top squirrel. We have almost half the surface carbon under our control to some extent, no wonder we emit so much carbon.

    [Response: I think a case could be made that the item you cite should be edited a bit, but I don’t think it’s quite fair to call the claim “absolute nonsense.” As an approximation to the situation, it’s almost correct. You’re quite right that the natural carbon cycle is not completely in balance — that’s why CO2 can fluctuate between glacial and interglacial cycles, or on longer time scales between the generally high Cretaceous values and the lower Pleistocene ones. Still, if one compares the annual imbalance needed to cause such changes with the kind of imbalance created today by anthropogenic CO2, it’s not such bad approximation to consider the unperturbed system to be in a state of balance. You are certainly correct, though, that the precision of the wording in the item could be improved. –raypierre]

  14. 64
    Dano says:


    Which is absolute nonesense. If nature was perfectly balanced there would be no glacial cycle. Right now, nature, in the absence of man, would be spewing out net carbon

    Whoa, Nellie.

    The statement you think you don’t like speaks to the carbon cycle, not to nature being balanced. The rest of your argument proceeds from this incorrect premise and is therefore incorrect as well.



  15. 65
    Coby says:

    Hi Matt,

    The article in question is here:

    I may need to clarify the wording a bit. But I did expand on this “there’s no balance” objection in the comments:

    “Balance is of course going to be relative to a timeframe. In the timeframe relevant to the discussion of an anthropogenic disturbance to the climate system it is quite clear that a balance did exist. This is evidenced by the stable concentration of CO2 in the atmosphere over the last several thousand years and also by the stable pH levels that have been reconstructed from analysis of foraminifera shells in ocean sediments. So, no significant changes in CO2 levels in the ocean and no significant changes in CO2 levels in the air over many thousands of years tells us that the large fluxes in and out of the ocean and the atmosphere were in fact in balance during all this time. This is NOT an assumption it is an OBSERVATION.”

    So while yes, on a long enough timeframe there are plenty of natural disturbances to a balanced carbon cycle, but I don’t see it as relevant and it is certainly not a credible reason to reject the anthropogenic nature of the CO2 rise.

  16. 66
    Coby says:

    I have done a minor rewrite, hopefully it will be clearer:

  17. 67
    Ike Solem says:

    Regarding the timescales of the response of the atmospheric and oceanic carbon dioxide pools to fossil fuel emissions: Perhaps it’s worth noting that there is a dynamic balance involved, more like a balance of rates then a balance of opposing forces.

    The limited ability of the oceans to absorb the CO2 that’s been injected into the atmosphere over the past century is due to physical mixing limitations. If the atmospheric half life of CO2 is ~100 yrs and the oceanic turnover mixing time is on the order of several thousand years, it will take around a millenia of high CO2 levels for the system to reach equilibrium. Measuring pH using fossil shells is then a method of tracking CO2 changes over longer timescales with coarser resolution. CO2 trapped in air bubbles in ancient glaciers is a much finer scale since it takes less then a year for the atmosphere to mix well, and CO2 residence time is around a century. The point is, even the strictly physical factors in modelling the carbon cycle are very complex, which is why a historical record is important for comparison (but see the second link below for a fair and balanced rebuttal to the ice record).

    Note that we will be feeling the effects of the CO2 in the atmosphere today for the next century at least, by any measurement. Water will rain out in a few days perhaps- most of the concern with the weather has to do with “‘what is the water vapor going to do over the next few days”. Climate science thus views water as a feedback effect of climate forcings (climate is averaged over some number of years), as this very site explains in great detail. water vapor.

    Even more complexities arise due to the chemical and biological interactions with CO2. Consider the ‘balance of payments’ between photosynthesis and rock weathering (CO2 removal mechanisms) on one hand, and biological respiration and fires on the other (CO2 addition mechanisms). Unlike water, CO2 won’t rain out of the atmosphere (unless carbonic acid forms in raindrops, goes into rivers, precipitates out as sea shells). However, as the physical record shows, the atmospheric levels have been fairly consistent and lower then today. Unless of course, you want to believe this: CO2 concentrations using 19th century technology

    It’d be nice to imagine that the biosphere, in response to higher CO2 levels, is growing in response and that there will be an acclerated rate of photosynthesis. What is the comparison between the current rate of fossil fuel emissions and the current rate of atmospheric CO2 increase? Isn’t it 50% of the total fossil carbon observed, with 50% accounted for by a hidden sink? Is it the biosphere serving as a atmospheric buffer for carbon dioxide from fossil sources? In one sense, the overall ‘health’ or activity of the biosphere might be measured by comparing the rates of the carbon cycle, the nitrogen cycle, the water cycle, etc. Finally, if this is so then why hasn’t the biosphere gone and absorbed the excess fossil CO2? That could be due to overlying factors involving deforestation and desertification. This statement isn’t meant to reassure that the biosphere would save us; it could perhaps adjust happily to a situation san human beings at a slightly higher temperature. Point being that the biosphere cycles a huge amount of carbon through the atmosphere every year in a distributed fashion, yet the atmospheric levels of CO2 remain fairly constant until humans start injecting tons of fossil carbon into the atmosphere. Too bad we couldn’t have injected all those billions of tons of CO2 into the Martian atmosphere, where they would have warmed the planet up a bit. It seems much less controversial when you talk about CO2 and the Martian atmosphere, doesn’t it?

    It does seems to indicate that planting trees as a form of temporary carbon storage (trees that live several hundred years, at least) would be a good idea. Indeed, the oceanographer John Martin said famously and irreverently that he could deliver an ice age with a tanker full of iron, while discussing the role of iron limitation on photosynthesis and nitrogen cycling in various regions of the open oceans. The general idea of promoting biosphere functions and limiting fossil carbon emissions has many positive effects. Other choices would include more of the Road Warrior theme: A warming future

  18. 68
    Matt says:

    If we talk human causes, then why is it never mentioned that we spend billions to prevent eutrophication of the freshwater systems on land which could take out three times the carbon as the ocean over short periods? In a normal glacial cycle, these systems should be packing co2 in thick layers leaving detritis on the floors of the lakes, indefinitely.

    Or, look at the little ice age. If we examine only the human causes, then it is easy to calculate that over a 750 period, medieval man could have removed 10 Gt of carbon from well managed sustainable forests. He built Europe on those forests alone, putting a good deal of that carbon into cities. He left the forests in aggressive growth mode, coppicing sections at a time. The deciduous trees would sprout back, leaving the existing root structure intact. My vostok ice core data shows a steady decline in co2 just during that period, prior to the little ice age.

    The problem with focusing on “bad” emissions is we need to understand how man works marginally different than “nature”.

    The second danger of focusing on “bad” emissions we may may fail to detect a more serious underlying problem.

  19. 69
    Hank Roberts says:

    Matt, I wish you’d get yourself a web page and invite comments. You write without any footnotes or references, so it’s very hard to say anything about it; you post chunks in whatever topic happens to be lively so there’s no continuity. Please do this in a coherent way somewhere.

    Single example not meant for followup here — most cut wood becomes sawdust and scrap and rots; most lumber lasts less long than the tree it would have stood in. Most standing trees are mostly ‘dead’ heartwood preserved from decomposition better than any human technique permits. Fallen trees in the forest have far more life in them than live trees because the heartwood is rapidly consumed and becomes other forms of life.
    Forest fires and logging turn trees rapidly into carbon dioxide. Few wood houses last a century. Little furniture lasts a century. Pallets and scrap last only a few years.

    You can look this stuff up. If you’d put numbers on your assumptions and say where you get them, it would be possible to think usefully about what you are writing. Right now it seems clever fiction for the most part. If you have a basis for it, please, find a forum and pull it together.

    [Response: I agree with this remark. Sometimes we let wild ideas through because they promote interesting discussion, or simply because we all have day jobs to attend to and can’t spend a lot of time evaluating each comment. However, repeated lengthy postings of the same general idea without making any attempt at validating it against results readily available in the literature does not serve any useful purpose. So, Matt, I would be pleased if you would keep your posts more concise, and refrain from continually re-introducing this topic until you have some new numbers or new ideas to offer. Also, as Hank says, it would be nice if you would try to keep your postings at least somewhat related to the article under discussion. –raypierre]

  20. 70
    Hank Roberts says:

    Matt, algae also produce nitrogen oxides. Eutrophication is a loser tactic. Look at your own aquarium and consider what you’re saying.

  21. 71
    Stephen Berg says:

    Re: #68, “The problem with focusing on ‘bad’ emissions is we need to understand how man works marginally different than ‘nature’.”

    Man works very differently from “nature”. Nature does not burn off millions of tons of coal for electrical uses, resulting in the emissions of billions of tons of CO2. Nature does not chop down millions of hectares of ancient forests, resulting in the emission of CO2 from decaying organic matter. Nature does not drill billions of barrels of oil from the ground only to burn it in automobiles, resulting in the emissions of billions of tons of CO2 into the atmosphere.

    “The second danger of focusing on ‘bad’ emissions we may may fail to detect a more serious underlying problem.”

    And this problem would be what? Can you name it? If not, why do you state such a thing?

  22. 72
    Ben Coombes says:

    Hi there,

    Sorry if this deviates from the debate but I’d just like to know if anybody knows of a link to Peter Wadham’s ‘Chimneys’ piece with regard to the THC? I’d certainly like to read what he’s said for an essay I’m doing, rather than relying on The Times article (A tenuous link to the ‘GOOD CLIMATE DEBATE’ thread after all?!).
    The EGU site -it was at their conference in Vienna that his remarks originally sparked the media hysteria- is most unhelpful as is university. Anyway, thanks for your time if anyone knows anything, much appreciated.

    [Response: We discussed this last year: – gavin]

  23. 73
    Steve Bloom says:

    Re #172: Plus there was a more recent post relating to the THC in January. To find it, check under the “oceans” post category in the right bar. Also, very likely Wadhams has a web site, and if so it may contain much of interest.

  24. 74
    Ben Coombes says:

    Re# Wadham,

    Thanks very much for the responses, I had read the previous posts with interest but wanted to try and find an official sourse for the original research other than ‘The Times’ article; no luck on a website for the good professor but I’ve found an email address and will post any links if I get a reply.
    Thanks again,

  25. 75
    Hank Roberts says:

    Ben, I found discussion in — one cite given, if you look far down in ths thread:

    You’ll find a reference to an article 3-4 years ago in which Waldman is a coauthor, and this in the comments:

    Now a little science, the descending columns of water that Wadham talks about are known as Open-Ocean Convection or Mid-Gyre convection and it occurs in the deep ocean under very specific circumstances, The only locations where it occurs with convection all the way to the ocean bottom are in the Greenland Sea, Labrador Sea, and perhaps occasionally in the Weddell Sea.

    However from USNA course on Polar Oceanography this is what they teach about OOC: It is an ephemeral process, in that it stops and starts, sometimes on the order of days, and occurs over a small area, with the convection restricted to a scale of ~100 km, but with descending plumes being even smaller.

    One of three sites for open-ocean convection in the Arctic is in the Greenland Sea as there exists a background cyclonic gyre, and a weakly stratified water column. Cold, relatively fresh surface water overlies a uniform column of Greenland Sea Deep Water (GSDW) which is relatively fresh, but very cold. In winter, the stratification is broken down by surface cooling and ice formation. Periodically, the cold Jan Mayen current and atmospheric conditions allow freezing to occur in a several hundred kilometer long bulge of pancake ice known as the Odden ice tongue. Winds blow this newly formed ice out of the Greenland Gyre region, so that the ice is melted at the southern edge, and continues to form on the Northern edge, so that the salinity of the gyre waters can be continuously reduced until deep convection can take place.

    end quote

    Sounds like something the submariners can tell us more about, if they’re allowed to!

  26. 76
    Matt says:


    You sent me off on a discovery of the nitrogen cycle, and I am beyond the basics.

    I find a lot of articles in google scholar of the form:

    “If you damn up this much phosphorous and nitrogen around the lake, then you get this much less co2 pumped out”

    Great research, once you deconvolve it to get what you want, how to be a better swamp.

    How is it that we have naturally stocked up on CO2, heat, water storms, and nitrogen just when nature wants to make a swamp?

  27. 77
    Hank Roberts says:

    Matt, get a web page, pull your ideas together with references, quantities, bases for your estimates.

  28. 78
    joel Hammer says:

    I don’t know where to put this, so this seems like a good place.

    A while back I pointed out that the Alaska Climatologist didn’t really think Alaska was warming due to “global warming.”

    Of course, their opinion was given short thrift, with one rebutter on this board pointing out that Barrows had experienced continued warming, and this was evidence, of course, for what else, human induced global warming from CO2 emissions.

    Now this:
    Hinkel, K.M., Nelson, F.E., Klene, A.E. and Bell, J.H. 2003. The urban heat island in winter at Barrow, Alaska. International Journal of Climatology 23: 1889-1905.

    The summary below comes from, where else, a bought and paid for web site I am sure controlled by big oil. But, my question for this group of scientists, Can this be true?


    Barrow, Alaska, which is situated on the Arctic Coastal Plain at the western edge of the Barrow Peninsula near the Chuckchi Sea at 71.3°N, 156.5°W, is described by the authors as “the northernmost settlement in the USA and the largest native community in the Arctic,” the population of which “has grown from about 300 residents in 1900 to more than 4600 in 2000.”

    What was done
    In mid-June of 2001, Hinkel et al. installed 54 temperature-recording instruments in and around Barrow, half of them within the urban area and the other half distributed across approximately 150 km2 of surrounding land, all of which provided air temperature data at hourly intervals 1.8 meters above the surface of the ground. In this paper, they describe the results they obtained for the following winter (December 2001-March 2002).

    What was learned
    Based on urban-rural spatial averages for the entire winter period, the urban area was found to be 2.2°C warmer than the rural area. During this period, the mean daily urban-rural temperature difference increased with decreasing temperature, “reaching a peak value of around 6°C in January-February.” It was also determined that the daily urban-rural temperature difference increased with decreasing wind speed, such that under calm conditions (< 4 knots or 2 m s-1) the daily urban-rural temperature difference was 3.2°C in the winter. Last of all, under simultaneous calm and cold conditions, the urban-rural temperature difference was observed to achieve hourly magnitudes exceeding 9°C.

    What it means
    For a town of less than 5000 people, Barrow has an urban heat island effect that is huge. Perhaps that is why global warming is thought by some to be so strong in high northern latitudes: even small congregations of people in these regions can create a significantly elevated near-surface air temperature where they live and work.

    [Response: The Hinkel et al study you quote is quite interesting (though not new), showing that energy use in the high Arctic can contribute to an ‘urban’ effect during the winter. The paper clearly states that there is no such effect in summer though (when Barrow has been warming almost as fast). One thing you forgot to look into is where the NWS station in Barrow is located and whether it even counts as ‘urban’ in the context of this study. (Actually it is some way out though the mean temperature anomalies are about average). One interesting point they raise is that any UHI phenomena vanishes when the wind is strong -exactly the same process that Parker (2004) used in his analysis. If this phenomena were widespread and seriously contaminating the processed records then the trends on windy days would be smaller than the trends on calm days. That they are the same indicates that this is not very large effect. I have nothing against this being studied further, but I doubt that any major changes will develop – basically because the ancillary evidence of warming is so clear (ocean heat content, glacier retreat, permafrost melting – especially in Alaska!). Better data is always to be wanted, but I wouldn’t put any money on it changing the picture radically. -gavin]

    [Response: The other point to make is that the existence of the UHI is no great shock. What you need to show is a UHI effect on *trends*. This is obviously much harder, as you need a long term record -William]

  29. 79
    Dano says:

    If I may add to gavin’s comment to 78:

    One thing you forgot to look into is where the NWS station in Barrow is located and whether it even counts as ‘urban’ in the context of this study. (Actually it is some way out though the mean temperature anomalies are about average).

    That cut-paste is from a well-known skeptic site (lookit the familiar format). I suspect they didn’t “forget” anything, as it has been shown many times that they don’t “forget”. But it would be nice to source it and not hide where the info. came from [e.g. what are you afraid of?].

    Until the “most of the surface temp rise = UHI” folks get out there and collect their own data on this well-studied subject, there won’t be anything but this type of argument.

    Anyone can find one station with glaring numbers. Let’s see hundreds with glaring numbers. Go git ’em. If they’re out there like you wish, it should be easy.



  30. 80
    Steve Bloom says:

    Re #78: Haven’t we discussed all of this before, not just the Alaska climatology site but Hinkel et al as well? I remember spending a few minutes locating the Barrow NWS station, which is unsurprisingly out by the airport south of town, and posting that information. I also remember pointing out (to you, I assume) that the Alaska site is simply neutral on the global warming issue. What the site says is that warming is not proceeding in an even manner relative to the CO2 rise, which is true and unsurprising. Even global average temp trends are pretty uneven relative to CO2 rise, and this effect tends to be much exaggerated when individual regions are looked at.

  31. 81
    Ben Coombes says:

    Re Wadham’s work on the diminishing number of chimneys in the Greenland Sea.
    The work is covered by two observational papers and one
    modelling paper. These are Wadhams et al (Geophysical Research Letters
    2002, 2004, on chimneys) and Wilkinson and Wadhams (Journal of Geophysical Research 2003, on salt fluxes). Thanks to Hank for his prior response.
    Back on the subject of good climate debate – has anyone seen the following uber-sceptic piece which has just appeared in Scientific American:

    Perhaps the complete antithesis to what Coby has done…

  32. 82
    Coby says:

    Well, there’re a few more articles in there aren’t there, and I haven’t read the comments yet!

  33. 83
    Stephen Berg says:

    Results of a poll done a couple of weeks ago:

    What upsets me about it is the apparent brainwashing by the media getting the general public thinking there is a lack of consensus or great disparities/disagreements between scientists. Here is the question I’m referring to:

    “Do you think most scientists agree with one another about whether or not global warming is happening, or do you think there is a lot of disagreement among scientists on this issue?”

    Most Agree 35
    A Lot of Disagreement 64
    Unsure 1

  34. 84
    Hank Roberts says:

    Stephen, that site appears to collect announced polling results and publish some of them (more for paying subscribers) but it’s a hodgepodge of what appear contradictory results (different polls, different questions).

    You quote one saying by 64:35 the American public thinks most scientists disagree whether global warming is happening (warming, not anthropogenic warming, just warming)

    On the same page is another saying
    “the world’s temperature may have been going up slowly over the past 100 years. … Do you think this has probably been happening…? — and 85% say yes, they think this has probably been happening.

    Different polls — so we can’t just boggle, but nevertheless:

    85% of the American public is convinced warming is happening;
    64% think the scientific community has no consensus on whether it’s happening.

    Where do the citizens get better information than the scientists?

    Answer — something about the polling is giving confusing results.

  35. 85
    Fernando Magyar says:

    Hmm, anthropogenic or not something is happening. I just read another article in the mainstream media which as a long time scuba diver I have been observing in person for some time now. It may not even be due exclusively to warming but the coral reefs are severly stressed around the globe. I am not a professional marine biologist but I think I can safely say that if the coral is dying the rest of those ecosystems are sure to follow. If nothing else it can’t be too good for the sport diving, fishing and tourism industries in the affected areas. See
    Anyway since we don’t have absolute proof that such warming trends are anthropogenic in nature (pun intended) why don’t we all just crank up the AC and go out and buy a new SUV or two. Why the heck would we want to err on the side of caution.

  36. 86
    Nice Post! says:

    Nice Post!
    Nice Post!

  37. 87
    Coby says:

    Coral reefs bleaching and dying is very serious and deserves wider coverage. I think it is a very strong indication of unprecedented (on human species timescales) warming and is impossible to dismiss as normal in any way given the multi-millenial age of these structures/organisms.