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Avery and Singer: Unstoppable hot air

Filed under: — david @ 20 November 2006

Last week I attended a talk by Dennis Avery, author with Fred Singer of Unstoppable Global Warming Every 1500 Years (there is a summary here). The talk (and tasty lunch) was sponsored by the Heartland Institute, and was apparently enthusiastically received by its audience. Still whoozy from a bit of contention during the question period, a perplexed member of the audience told me privately that he thought a Point/CounterPoint discussion might be useful (he didn’t know I wrote for realclimate; it was just a hypothetical thought). But here’s my attempt to accommodate.

Note: The Points are paraphrases from the slides and my notes from Avery’s talk.

Point. The existence of the medieval warm and the Little Ice Age climate intervals, and the 1500 year D-O cycles in glacial climate, proves that the warming in the past decades is a natural phenomenon, not caused by human industry at all.

CounterPoint. The existence of climate changes in the past is not news to the climate change scientific community; there is a whole chapter about it in the upcoming IPCC Scientific Assessment. Nor do past, natural variations in climate negate the global warming forecast. Most past climate changes, like the glacial interglacial cycle, can be explained based on changes in solar heating and greenhouse gases, but the warming in the last few decades cannot be explained without the impact of human-released greenhouse gases. Avery was very careful to crop his temperature plots at 1985, rather than show the data to 2005.

Point. Hundreds of researchers have published on the Little Ice Age and Medieval warm climates, proving that there is no scientific consensus on global warming.

CounterPoint. Natural and human-induced climate changes both exist. Studying one does not imply disbelief in the other.

Point. Human populations of Europe and India thrived during the medieval warm time, so clearly warming is good for us.

CounterPoint. No one asserts that the present-day warmth is a calamity, although perhaps some residents of Tuvalu or New Orleans might feel differently, and the Mayans may have been less than enthusiastic about the medieval climate. The projected temperature for 2100 under business-as-usual is another matter entirely, warmer than the Earth has been in millions of years.

Point. NASA identified a huge energy hole over the tropical Pacific, which sucked out as much heat as doubling CO2. NASA scientists asked modelers to replicate this, and they failed, by 200-400%, even when they knew the answer in advance!

CounterPoint. This appears to be a reference to Chen et al., 2002. Satellite data from the equatorial Pacific showed an increase in IR heat flux to space of about 5 W/m2 from 1985 to 2005, and a decrease in reflected visible light of about 2 W/m2, leaving a 3 W/m2 change in net heat flux.

Avery’s implicit promise would seem to be that with rising CO2, the heavens will part and let the excess energy out, a Lindzenesque mechanism to nullify global warming. The measured change in heat fluxes in the equatorial Pacific is indeed comparable to the radiative effect of doubling CO2 but the CO2 number is a global average, while the equatorial Pacific is just one region. The measurements probably reflect a regional rearrangement of cloud cover or ocean temperature, a decadal variation with no clear implication at all for the global mean heat budget of the Earth. The global heat imbalance has been inferred (Hansen et al, Science, 2005), and it is consistent with rising greenhouse gas concentrations and transient heating of the ocean.

A word about models in science (as opposed to in think-tank economics, Mr. Avery’s home turf). Models would have little use if they were so easy to bend into any answer we thought we knew about in advance. One can always be critical of models, but there is no model that avoids global warming by parting the heavens, or that is exquisitely sensitive to solar variability but insensitive to CO2, the worlds that Mr. Avery wishes for.

Avery’s talk also dusted off many of the good old good ones, like the cosmic-ray / cloud connection, the temperature lead of CO2 through the deglaciation, the Antarctic warming, the cooling during the period 1940-1970, the now-resolved satellite temperature discrepancy from ground temperatures, and even the ancient CO2 band saturation myth.

In addition to Chen, Avery offered to us the work of Maureen Raymo and Gerard Bond. Bond didn’t think his work cast any doubt on the possibility of anthropogenic warming, neither do Raymo or Chen. Hint: if you want to sound like you know what you’re talking about, the accent on the fourth syllable of foraminifera, not foraminifera.

Point. Environmentalists do what they do because they miss having their mommies reading Grimm’s Fairy Tales to them. They like getting all scared.

CounterPoint. To hybrid-phrase Thomas Jefferson and Richard Feynman, I tremble for humanity when I reflect that nature cannot be fooled. You’re damn right I’m scared.

209 Responses to “Avery and Singer: Unstoppable hot air”

  1. 1
    Charles Muller says:

    David, you write : “the warming in the last few decades can only be explained as a result of human-released greenhouse gases.”

    When I take Nasa Gistemp for temperature trend anomaly, it gives me (annual oct-nov) +0,49°C for 1977-2006, +0,41°C for 1916-45. So, my first point : the warming of the past few decades is not so exceptional, when compare to another recent period – with of course much less atmospheric CO2, CH4, CFC, SF6, etc. in 1916-45 than in 1977-2006.

    My second point : to explain this 0,49°C trend by GHG’s, we must of course exclude other possible causes. Among them :
    – natural / chaotic variability (for example, strong NAO+ phase, the two strongest El Nino ENSO of the records 1983-84, 1997-98, etc.)
    – trends in anthropic aerosols (it seems for example that SO2 emisssions are decreasing between 1977 and 2006, regularly in Europe and USA, more recently in Asia : can we quantify the direct and indirect radiative forcing of this decrease? cf. Streets 2006 GRL)
    – trends in nebulosity, SW downward and surface insolation (for SWD, the Baseline Surface Radiation Network/World Radiation Monitoring Center finds a strong increase between 1992 and 2003, mainly on mid. and high latitudes where the warming is more pronounced, cf. Wild presentation at BSRN meeting on May 2006, and Wild 2005 or Pinker 2005 on global brightening).

    So, do you think these three potential other causes of warming are negligible (or even indefensible) ?

    [Response:How about “cannot be explained without human-released greenhouse gases”? David]

  2. 2
    Coby says:


    Why in the world do you think climate can only be influenced by one thing at a time?

  3. 3
    Hank Roberts says:

    Charles, this history will bring you up to the late 1980s, when the various factors you’re concerned about began to be incorporated in the science. I think you’ll be glad to see how you’re thinking the same way the researchers did, and read up on how they dealt with the questions.

    It’s heavy reading, give it time.

  4. 4
    Hank Roberts says:

    PS, here’s the link to the NCPA article:

    Here’s Sourcewatch’s info page on NCPA

  5. 5
    Charles Muller says:

    Coby, I suggest climate (more precisely surface temperature) is not influenced by just one thing (GHGs), rather by different factors, and I’d like to know how we presently estimate the importance of each factor in the past 30 years’ 0,49°C land+ocean warming trend.

  6. 6
    Hank Roberts says:

    Charles, the basics are here — type ‘forcings’ in the Search box.

  7. 7
    Steve Bloom says:

    Re #5: Charles, in addition to the link Hank provided, have a look at the “FAQ” and “Greenhouse gases” categories on the right bar. The relevant posts should be pretty easy to pick out.

  8. 8
    Eduardo Ferreyra says:

    Well, it is nice to see that after beating in the bushes with your counterpoints, and not coming with anything new or important, the end result is you give Singer and Avery the reason. Good. It was time.

  9. 9
    Charles Muller says:

    #5, 6, 7
    Hank, Steve, thanks for your references and suggestions. I’m afraid they do not precisely answer my questions. These questions deal with warming-to-forcing attribution of the last three decades, and their uncertainty, not a general point on the basic physics of GH or aerosol or anything else. (Nor a skeptical and oil-funded manifesto: sure I’m quite skeptic on excessive alarmism, but open-minded on climatic debate and insensitive to oil-industry lobbying).

    Let’s be more precise. The BSRN data I mentioned find for example on recent period (1990’s onward) a positive SWD trend superior to the LWD trend (0,47 W/m2/y vs 0,26 W/m2/y in stations analyzed by M. Wild). I remember TOA and surface budgets are two different maters, but I just ask to David (or yourself) if the SWD positive trend could account for surface temperature warming of the same period. Maybe the answer is negative, after all, I just need an explanation.

    [Response: You’ve answered your own question. Surface forcing is not the same as TOA forcing, and it is only for TOA forcing (though strictly, it is defined at the tropopause) that we get the predictive power in the global mean temperature field. I would add a few other cautions as well: Firstly, the BSRN data are very noisy, and it is extremely unclear whether the decade or so of sparse measurements is sufficient to derive even local trends, let alone extrapolations to the whole globe. Secondly, model simulations over the 20th Century which include GHG and aerosol trends see reductions in SWD even as the surface temperatures are rising , but also indicate that for short time periods, decadal variability makes it extremely difficult to discern these trends over short periods. – gavin]

  10. 10
    Steve Bloom says:

    Re #8: Eduardo, how nice to hear from you! I see you’re keeping your web site up to date with contributions from so many of the usual denialist suspects and, oh, how is the family cement business? I haven’t checked lately, but do cement kilns still rank as pretty much the most intensive industrial source of GHGs? Just curious…

  11. 11
    Randolph Fritz says:

    Sigh…being a propagandist means never having to say “I was wrong.”

  12. 12
    Charles Muller says:

    Thanks Gavin. Concerning the “noisy data”, you probably know that BSRN measurements have been correlated with a wide range of other databases by Wild and Pinker (ISCCP, Gewex, GEBA, CMDL, Big Bear Solar Observatory for terresrial reflectance, etc.). Maybe they underestimate the margin errors of their global quantification, but it seems quite unlikely that 1992-2003 global brightening is a complete artifact. Anyway, my question was : if this is grossly correct (and not an artifact), could that explain part of the warming for the three decades’ period we discuss here?

    Your concern with noisy data rises another problem: except perhaps for GHGs, many datas are still noisy (or with “low level of understading”, according to IPCC formulation)! I guess it’s true for the other potential cause of recent warming I suggested, the decrease of some aerosol emissions – and hypothetic radiative effects of this decrease, depending of many microphysics factors still difficult to implement in models.

    At last, OK for SWD decrease with surface warming in some model simulations – precisely because there’s no one cause of warming / cooling for the XXth century. The fact that decadal variability is a reality and that we’re speaking of a small amplitude in a short period (0,49°C / 1977-2006) explains why I’m not at ease when I read definitive statements on GHGs quasi-exclusive signature for recent warming.

    [Response: You maybe misunderstand what I mean by ‘noise’ – I don’t mean errors or incorrect readings, but the ‘noise’ associated with chaotic fluctuations in the weather. These will show up in multiple datasets (such as ISCCP) as well, but the standard deviations of most of the surface flux fields mean that you cannot define a statistically signifcant trend in only 10 or so years of data. The recent ‘global’ brightening, I would argue, is in fact likely to be an artifact – it is not at all clear in the ISCCP-FD data for instance, despite locally high correlations to the BSRN stations. Regardless, these surface flux changes are not the key metrics for surface temperatures (which might be a little paradoxical, but bear with me).

    Attribution of the temperature changes to causes is done using consistent modelling of all the physically based theories of climate change indivually and together, with the match to the data determining which factors are important when. There is no a priori reason to think that any one factor is dominant, and over much of the recent past that is exactly the case. There are periods when solar goes up, CO2 goes up, volcanoes are quiet and temperatures rise. There are other times when solar goes down but GHGs rise etc. Given the uncertainties in the solar forcing (in particular), but also the aerosol forcing, these complex interactions can’t be easily teased apart to give precise percentage attributions for each period – this is particularly true up until about 1980 – see the simulations in our recent papers. I discussed this recently in . The best explanations (though possibly not the most aesthetically pleasing) are that the early century warming was due to a combination of rising GHGs, rising solar, and infrequent volcanism. Post WWII, aerosols increased markedly, solar stabilised, CO2 had a bit of plateau, and volcanism picked up (particularly Mt Agung in 1963) – hence slight cooling. There is a role for internal decadal scale variability there as well. However, post 1980, the signal from GHGs starts to come out of the noise, and now is the dominant forcing over all others. This was predicted at the time, and those predictions have been bourne out. So in general you are correct, it is foolish to expect a single variable to be dominant – but that is pretty close to the situation we are finding ourselves in. And the dominance is increasing. -gavin]

  13. 13
    Joel Shore says:

    Actually, the site that was pointed out in #10 has an article on it ( ) by Avery in which he spends most of the article highlighting a recent paper by Polissar et al. in the Proceedings of the National Academy of Sciences which he seems to believe undercuts anthropogenic global warming. The strange thing is, however, that when you go to paper abstract itself ( ), you find that the last sentence says: “These results highlight the sensitivity of high-altitude tropical regions to relatively small changes in radiative forcing, implying even greater probable responses to future anthropogenic forcing.”

    One finds more and more that denialists are selectively mining facts from papers and then drawing conclusions from them that completely disagree with the conclusions of the authors themselves. It seems to be about the only way they can try to claim that any non-negligible fraction of the peer-reviewed literature supports their point-of-view.

  14. 14
    Charles Muller says:

    #1 David comment

    No problem with the new formulation you suggest! I totally agree it is impossible to explain recent warming without GHGs anthropic emissions. And I consequently disagree with Avery and Singer’s point that 1750-2000 warming (a fortiori 1977-2006) can be explained by natural variations alone. More GHGs imply atmospheric and surface warming: it’s a physical non sense to deny this basic statement. Maybe I should have precised this point to avoid overinterpretations of my objections…

    [Response:I made the change in the text. Thanks. David]

  15. 15
    Charles Muller says:

    #12 Gavin response

    Thanks for the long explanations and the link to Nasa Giss radiative forcings estimates. Reading the graph (a), it’s difficult for me to understand the first warming of XXth century (0,41°C 1916-45), because you’ve nearly zero solar irradiance forcing (orange curve) and a seemingly nul-sum GHGs and aerosol forcings (green and blue+purple curves). And as previous period 1880-1915 has no particular trend except a strong volcano (negative) forcing, I suppose oceanic inertia is not involved (ie release in 1916-45 of heat accumulated in 1880-1915). The only way I can explain that is a high climate sensitivity to GGHs – but (maybe wrongly) I’ve in mind that CS of GISS is not particularly high among 2-4,5°C margin of other models.

  16. 16
    Stephen Berg says:

    Excellent rebuttal, David! I’m glad your stomach was able to make it through the presentation in one piece!

  17. 17
    CobblyWorlds says:

    From the summary of Avery’s talk.

    “Are human activities, including the burning of fossil fuel and forest conversion, the primary – or even significant – drivers of this current temperature trend? The scientifically appropriate answer – cautious and conforming to the known facts – is: probably not.”

    Does this ‘alternate theory’ account for

    1) The cooling trend in the stratosphere as opposed to warming in the tropo.

    2) The trend in diurnal range, night warming more than day.

    3) The seasonal trend, winters warming more than summers.

    4) The last 3 decades of warming despite the lack of trends in solar activity over that period that may otherwise explain that warming.

    I wasn’t at the presentation so I don’t know if these factors were addressed. But the author obviously doesn’t consider them important enough to have made it into the summary.

    However if this is meant to be an “alternate theory” then shouldn’t it provide an explanation for the observations that the established “CO2 theory” predicts?

    If the theory doesn’t address the observations explained by the theory it seeks to challenge. Then it doesn’t seem to me to be much of a challenge. My response to such a challenge would be; go away re-examine the work, come back when you’ve put some meat on the bones and the theory actually addresses the available observations.

    Sorry but just citing ‘natural cycles’ doesn’t cut it for me. It sounds a bit too much like ‘god does it’.

    [Response:I agree with you, all the way from climate fingerprinting (your points 1-3) to the scientific method. The point of the presentation was to pursuade, not to engage scientifically. The ancient art of rhetoric. David]

  18. 18
    Pascal says:

    re # reponse Gavin to Charles

    Hi Gavin

    When you speak about your “recent work” I don’t understand why the aerosol direct forcing (blue curve) is not “refreshed” since 1990.
    I noted It was the same on numeric data up to 2003.
    As Charles told you, there is a great decreasing of sulfates aerosols (and BC aerosols) since 1980-1990.
    And it seems that the sum of sulfate and BC aerosols forcings is decreasing in absolute value.
    In taking account of this effect the global TOA forcing between 1976 and 2005 is near +2W/m2.
    How can you explain the relatively weak temperature increasing in this period? (near 0.5°C)
    And what is the part of thermal inertia in this?

    [Response: Aerosol emission data sets take a long time to accumulate and validate. At the time we ran those experiments, we did not have the updates for 1990 to 2000 and so we left it as constant for lack of better information. You should also note that the emission data are subject to frequent revision as estimates of industrial and residential activity get adjusted. There is some evidence of decreasing sulfates and BC in Europe and the US over this period, but that is probably matched by an increase in China and India, and so the global impact is not clear (where do you get 2 W/m2 from?). With respect to the temperature response, look at the subsequent paper Hansen et al (subm): in our simulations the recent increase is reasonably matched (possibly a little underestimated), and thermal inertia implies about the same about warming still to come from that rise. -gavin]

  19. 19
    egbooth says:

    Thanks for the post, David. I’m just curious about what the feeling was like at the presentation. Did you or anyone else present any of these counterpoints during the Q&A session? It sounds like the audience was in real need of getting the record straight on Avery’s horrible logic.

    I know that realclimate gets a lot of readers but it seems like you would be much more effective if you would have just debunked Avery immediately after he spouted all of his BS. I kind of feel like realclimate is just preaching to the choir a lot of the time and the audience at the talk would have gotten a lot more out of these counterpoints. Thanks.

    [Response:I did correct what I thought were inaccuracies in the question period, but I’m not the world’s best oral debator. I write better than I talk. I don’t know what I could have conveyed to the audience, watching the clash of the weirdbeirds, other than disagreement. David]

  20. 20
    Neal J. King says:


    I resonate to your point: As long as the general populace is addressed mainly by hucksters, they will believe in snake-oil. Unless the actual state of the science is also being presented, one can’t blame them for giving hucksters the benefit of the doubt.

    This is why some folks are working on a point-by-point response to Monckton’s article in the Sunday Telegraph of a few weeks ago, to point out not only errors, but also specific abuse of references. This is being generated at Wikipedia:

    I may ask for help from RC folks from time to time, as an authoritative response to all points is certainly beyond my personal depth. I already have some requests out to Cobblyworlds and chris, in the “Cuckoo Science” thread of RC: .

  21. 21
    Pascal says:


    Thanks Gavin

    For the 2 W/m2 between 1976 and 2005.

    GHGs +O3 : +1.32W/m2


    from Wild 2006 this link (in association with your data) indicates an aerosol level in 2000 equal grosso-modo to the 1960-1970 level.
    If the slope is the same we have in 2005 RF BC = 0.3 W/m2 and RF aerosols (direct and indirect effects) = about -1.0W/m2.
    For all aerosols (BC+negatives) in 1976 RF = -1.16W/m2 and in 2005 = -0.7W/m2.
    The variation is +0.46W/m2

    For the sun there is no variation.

    for the stratospheric aerosols it’s also very difficult to estimate.
    With a polynomial curve to smooth this RF of volcanoes, I estimate +0.3W/m2 for this period(???)

    The sum (1.32+0.46+0.3) is 2.08 W/m2.

    It’s clear it isn’t accurate and the greater imprecision is in the aerosols (what a surprise!)

  22. 22
    Charles Muller says:

    On this point :
    “2) The trend in diurnal range, night warming more than day.”

    I recently read (Rose et al. 2005) :
    New data acquisitions are used to examine recent global trends in maximum temperature, minimum temperature, and the diurnal temperature range (DTR). On average, the analysis covers the equivalent of 71% of the total global land area, 17% more than in previous studies. Consistent with the IPCC Third Assessment Report, minimum temperature increased more rapidly than maximum temperature (0.204 vs. 0.141°C dec^-1) from 1950-2004, resulting in a significant DTR decrease (~0.066°C dec^-1). In contrast, there were comparable increases in minimum and maximum temperature (0.295 vs. 0.287°C dec^-1) from 1979-2004, muting recent DTR trends (~0.001°C dec^-1). Minimum and maximum temperature increased in almost all parts of the globe during both periods, whereas a widespread decrease in the DTR was only evident from 1950-1980.

    Like CobblyWords, I thought an ES-driven warming should act comparatively more on Tmin than Tmax. But in fact, some studies (Braganza et al 2004 for example) conclude that models often overestimate Tmax / observations over the XXth century. So, maybe this new trend in DTR is a confirmation of models validity. If so, the argument of warmer-night-than-day should be used with caution.

  23. 23

    Re: David’s comment to #19 “not the best debater”.

    This is the problem in a nutshell. People who examine and try to understand the whole of the evidence are finding themselves in opposition to people whose expertise is advancing a point of view based on a selection of the evidence. We are playing different games here.

    Scientists want to know how things stand. Debate club alumni want to advance a point of view.

    The high school debate team ethos, which I believe is not dramatically different from the ethics of attorneys and many politicians, holds that it is morally not just tolerable but commendable to construct the most convincing possible argument for an arbitrarily chosen conclusion from the available evidence. In this view, one should be essentially indifferent to which side of the case one is arguing, and strive simply for argumentative competence.

    Journalists (and juries), influenced by this, seem to see themselves as referees in a debating contest rather than as participants in winnowing the evidence to extract a course of action. The general public sees a clash of skills, not of ideas; of presentation rather than of content.

    In an essay on an entirely different topic (“Bambi vs Godzilla: Why Art Loses in Hollywood”, Harper’s 6/05) the writer David Mamet offers the following:

    “Law, politics and commerce are based on lies. That is, the premises giving rise to opposition are real, but the debate occurs not between these premises but between their proxy, substitute positions. The two parties to a legal dispute (as the opponents in an election) each select an essentially absurd position. “I did not kill my wife and Ron Goldman,” “A rising tide raises all boats,” “Tobacco does not cause cancer.” Should one be able to support this position, such that it prevails over the nonsense of his opponent, he is awarded the decision. …

    “In these fibbing competitions, the party actually wronged, the party with an actual practicable program, or possessing an actually beneficial product, is at a severe disadvantage; he is stuck with a position he cannot abandon, and, thus, cannot engage his talents for elaboration, distraction, drama and subterfuge.”

  24. 24
    Arthur Smith says:

    The thrust of the Avery/Singer paper to which you point to the summary, seems to be that the D-O cycles (1500 years or so) are continuing to the present. They quote Greenland ice core data, Antarctic data, sedimentation, cave crystal growth, tree rings and a number of other pieces of evidence for this. And yet, according to the discussion on realclimate a couple of weeks back, D-O cycles ended (by definition?) at the end of the last ice age 11,000 years ago. Is there any peer-reviewed literature on this “continuation”? They seem to be making a big deal out of it…

    [Response:Climate variations whatever their periodicity are much weaker in the Holocene. Gerard Bond reported a 1500 year cycle in some sediment characteristics in the North Atlantic, and you do have medieval and Little Ice Age climates that suggest 1500 years. G. C. Bond et al., Mechanisms of Global Climate Change at Millennial Time Scales, Geophysical Monograph Series, vol. 112 (American Geophysical Union, Washington, DC, 1999), pp. 35-58. If the 1500 year cycle does exist in the Holocene, it’s weak, and can’t explain all of our record-breaking weather. David]

  25. 25
    Edward C. Mangold says:

    The comments of Michael Tobis are especialy meaningful to me. I was brought up in a religous home and school environment in which deception was considered a vice and truth was to be sought above all. It wasn’t until I got to graduate school when I found out how professionsl wrestling actually works. As far as observing tactics, we didn’t have a debating team when I was in school so I didn’t have the opportunity to witness the mode of operation.

    Tobis Wrote: “…it is morally not just tolerable but commendable to construct the most convincing possible argument for an arbitrarily chosen conclusion from the available evidence.” I was brought up to believe that as a scientist I was obligated to seek “truth” above all, and that selectivly choosing only that data which backs up a favored explanation is a form of dishonesty.

    Another factor is the observation of a scientific “debate” as a blood sport in which the blows to and demolition of one side by his/her opponent is a bigger attraction to observers than resolving the scientific isssue at hand.

    Edward C. Mangold

  26. 26
    Alexey Voinov says:

    The most amazing example of lapse of logic in these speculations is this paragraph:
    “Importantly, if the current warming trend is, as the evidence suggests, part of an entirely natural climate cycle, actions proposed to prevent further warming would be futile and could, by imposing substantial costs upon the global economy, lessen the ability of people to adapt to the impacts “both positive and negative” of climate change.”

    Wait a minute: who’s talking about any interference with the “natural cycle”? Or should we consider the release of all the fossil CO2 natural? Did this also occur before, during the other D-O cycles?
    Suppose there are natural cycles and suppose that the warming we see today is driven by one of these cycles. But aren’t we then exacerbating the problem by releasing all the additional CO2? Shouldn’t we at least take care of what we have and are doing on top of the natural cycle? Aren’t we adding this disturbance at the worst time we could possibly think of? Aren’t we putting the whole climatic system at further risk by swinging it out of synch when it may be most sensitive to this kind of forcings?

  27. 27
    Bryan Sralla says:

    Thank you to Charles Muller for articulating a position I share.

    Gavin: you stated “And the dominance (of GHG’s) is increasing.”

    But my question to you is this. Will that dominance continue increasing or be offset by changes in some of these other forcings and associated feedbacks in the future? How can accurate future projections of natural and man-made aerosol emmissions be made, and since the aerosol indirect effects are poorly modeled, how can we be confident about how these might affect our global mean temperature projections? Would significant increases in volcanic activity and increasing dirty coal combustion over the next couple of centuries re-set the thermostat at a lower temperature? What do model runs of increasing aerosols, decreasing solar, increasing C02 look like? It seems to me the full spectrum of plausible scenarios should be modeled and shown in a cone of uncertainty, not just a “business as usual scenario”.

    Obviously, a perfect storm scenario of increasing GHG’s, increasing or stable solar, and decreasing aerosols will yield varying amounts of globally-averaged warming (as we are observing). Such a scenario is not surprising since we keenly understand the basic physics (but maybe less-well if the physics is accurately treated in the AOGCM’s). But should we expect future surprises, or are you confident that possible changes in other forcings are well accounted for and will likely play only a small role? Sorry for the rambling question.

  28. 28
    Charles Muller says:

    Well, if Arctic was very warm during MWP 800 years ago (a classical skeptic argument) and is very warm now (everybody agree), it’s quite difficult to conclude we assist to the 1470 yr cycle of D-O events. 700 yr missing.

  29. 29
    Charles Muller says:

    Pascal, if your count is OK, there’s a problem :
    1916-1945 : approx. +0,5 W/m2 > +0,41°C
    1977-2006 : approx. +2,0 W/m2 > +0,49°C

  30. 30
    Steve Bloom says:

    Re #19 response: David, I’m very curious as to your assessment of the attendees. In particular, was there much in the way of non-fringe media?

    More generally, I think this book and its attendant publicity effort needs to be seen as part of a larger plan by the usual suspects to get their information out into the media before the AR4 comes out. Other elements include Monckton’s Telegraph pieces, Pat Michaels’ planned meta-paper purporting to show an overall bias in climate science, and the offer by the American Enterprise Institute of $10,000 to “credible” climate scientists willing to write papers critical of the AR4.

    [Response:There was no media there at all, it was mostly members and donors of the Heartland Institute. I gather they have lunch meetings on a variety of topics. I would guess there were very few “non fringe” people. For Avery, it was a book signing. Maybe his publisher flew him out. David]

  31. 31
    Hank Roberts says:

    Yep. Lying is good business practice. Why hope the WSJ editors would discuss climate?

    Law Blog » The Curmudgeon’s Guide: Defending Depositions
    When you are guilty the best way avoid getting caught lying is not to dispute the facts but … It is better to commit the sin of omission than commission. …

  32. 32
    Hank Roberts says:

    Some learn their ethics from the WSJ, as quoted above; some of us from other sources.

    This was my grade school ethics reading. There are parallels in many other schools:

    Relevant in today’s newspaper:

  33. 33

    Thanks Edward.

    However, I must ruefully note that you demonstrate your claim that you are not experienced at the debating game when you write:

    “Tobis Wrote: “…it is morally not just tolerable but commendable to construct the most convincing possible argument for an arbitrarily chosen conclusion from the available evidence.” I was brought up to believe that as a scientist I was obligated to seek “truth” above all,

    I presume you realize that I agree with you, but your first sentence could easily, indeed more easily than not, be interpreted to mean that I don’t. If you had said

    Tobis questions an “ethos, which … holds that it is morally not just” etc.

    I would be less exposed to this misinterpretation. People who argue on selected evidence have been known to go a long way on thinner gruel.

  34. 34
    Dano says:

    RE 13 (Shore):

    One finds more and more that denialists are selectively mining facts from papers and then drawing conclusions from them that completely disagree with the conclusions of the authors themselves. It seems to be about the only way they can try to claim that any non-negligible fraction of the peer-reviewed literature supports their point-of-view.

    If I may disagree slightly with your excellent comment, this is a tried-and-true tactic that was (IMHO) perfected by see-oh-too a number of years ago; in fact, I can tell folk use see-oh-too as cut/paste material, as their references are in a slightly different style than, say, MLA.

    RE 23 (Tobis):

    A-men brother.



  35. 35
    Alan Gregory says:

    Couldn’t find a general e-mail address to use in notifying the site about this research.

  36. 36
    Eli Rabett says:

    There is an interesting dynamic at work. The denial crowd has become increasingly shrill to deal with the avalanche of science demonstrating the reality and bad effects of global warming. They have ramped up their personal attacks on a bunch of folk who, based on past behavior, would rather just do their science. The scientists, if only to save their good names are starting to emerge from their labs and enter the public arena. They are also beginning to recognize that not every Holiday Inn Climate Scientist is their colleague.

    Since the scientists have more credibility, the denialists are trying to drive them out of the public area before they gain more traction. This is going on at Eli’s favorite blogs, (look at the posts between Nov 15 and 21) but you have to ask yourself, why there, why this, why now.

    The answers may not be pleasing, but they are revealing.

  37. 37
    Ron R. says:

    and the offer by the American Enterprise Institute of $10,000 to “credible” climate scientists willing to write papers critical of the AR4

    Is his True? If so, Wow!

    Just looked it up. Yep. Saw this comment on Science and politics of global climate change “My wife read this blog, saw the figure of $10,000, and asked me sweetly, “Are you SURE that climate change is real? We could really use the money.”

    Talk about desperate and dishonest. For years the professional denialists been claiming that climate scientists are “on the take” only supporting AGW because of grants, now here they are brazenly trying to buy off scientists. That should be enough for anyone.

  38. 38
    Ron R. says:

    From the website, Avery’s qualifications:

    Dennis T. Avery is a senior fellow of the Hudson Institute. He has served as a policy analyst for the U.S. Department of Agriculture, the U.S. Commodity Futures Trading Commission and the U.S. Department of State, where he won the National Intelligence Medal of Achievement in 1983. His book, Global Food Progress, was published by Hudson in 1991. Reader’s Digest excerpted his article on the Medieval Warming, “What’s Wrong With Global Warming?” in October 1999.

    I feel so much better now knowing that Avery’s a “credible” climate scientist. So is he going to get that $10,000?

    Then again, that’d be robbing Peter to pay Paul.

  39. 39
    Paul G says:

    ==== Eli Rabett said: ====
    There is an interesting dynamic at work. The denial crowd has become increasingly shrill to deal with the avalanche of science demonstrating the reality and bad effects of global warming.

    Shrill? The shrillest voices are from the constant fearmongering propagated by environmental doomsters.

    I know of not a single person who is a “denialist”. It is a term invented as a rhetorical trick to silence any questions (and I mean ANY questions) about AGW. The term “skeptical” is more accurate, and the term “realist” even better.

    But being a religion in a sense, questioning ANY of the orthodoxy of AGW is not allowed. Out heretics!

    ==== Eli Rabett further states: ====
    They have ramped up their personal attacks on a bunch of folk who, based on past behavior, would rather just do their science.

    Surely good science can withstand the rants of a few; possibly not. 99% of the news reported on climate supports the belief in AGW, yet our emissions continue to rise. Silencing any and all critics also won’t reduce GHG emissions. It’s also bad for free speech.

    ==== Eli Rabett said: ====
    The scientists, if only to save their good names are starting to emerge from their labs and enter the public arena. They are also beginning to recognize that not every Holiday Inn Climate Scientist is their colleague.

    Too many scientists have emerged from the lab already. This is now a public policy issue for the public to decide.

    ==== Eli Rabett said: ====
    Since the scientists have more credibility, the denialists are trying to drive them out of the public area before they gain more traction.

    You sound paranoid. Explain how these so-called “denialists” would drive scientists out of the public arena? I’m really curious.

    [Response: You don’t know a denialist? There is a whole denial industry that is now well-documented, and Singer is a long-time player in this. For a brief introduction, start here. -stefan]

  40. 40

    Re “But being a religion in a sense, questioning ANY of the orthodoxy of AGW is not allowed. Out heretics!”

    Well, yes, not all viewpoints are tolerated for serious discussion when the scientific issues involved are well settled. I can’t imagine the Astronomical Journal printing a paper defending geocentrism, or Brain, Behavior and Evolution printing one defending creationism. That’s the proper analogy to denialism, since the science behind it is equally crappy.

  41. 41
    Pascal says:


    yes Charles there is a problem and the answer of Gavin isn’t (sorry Gavin) very precise and convincing.
    But how can we know the good counts if we don’t know aerosols impact?
    Another question:
    In AR4 there is an estimation of aerosols RF, I suppose.
    Is this estimation built with the 1990’s or more recent aerosols amounts?

  42. 42
    Dan J says:

    “I know of not a single person who is a ‘denialist’.”

    I do (unfortunately). Your first clue is when they shout “It’s not happening!” and then have no real reasons to back that up, and your second clue is when they claim to have given hundreds of such talks across the nation, saying this and not much more. You will see them if you pay attention.

  43. 43
    CobblyWorlds says:

    Re #22 Charles Muller,

    Thanks for providing that info.

    However, I asume you don’t mean Rose 2005, rather Vose/Easterling et al GRL 2005 “Maximum and minimum temperature trends for the globe: An update through 2004. Geophys. Res. Lett., 32, L23822.”

    I’ve had a quick scan of that paper, very interesting.

    As I’m not a professional I can’t suggest why this might be, and have until know missed that paper. I’ll await the summary on this issue in AR4.

  44. 44
    Tom Pollard says:

    #26: First, you ask ‘who’s talking about any interference with the “natural cycle”?’ The quote to which you’re responding does not say anything about ‘interfering’ with the natural cycles.

    Second, you ask “But aren’t we then exacerbating the problem by releasing all the additional CO2?” The point is that reducing global CO2 emissions only appears to be possible at a high economic cost. If CO2 is only a marginal contributor to the recent global warming, then significant warming might be inevitable regardless of our efforts to reduce CO2 emissions, yet these efforts would tie up resources that could be better spent addressing the consequences of warming.

    To use an analogy, if your basement is flooding because water is coming is leaking through the roof and seaping in through the cellar walls, and you have $200 to spend, are you better off patching your roof or buying a sump pump? Patching your roof might slow the rate at which your basement is filling with water, but it won’t stop it (or even slow it dramatically). With limited resources, you’re probably better off spending them on the pump.
    Similarly, if only 25% of global warming is attributable to increased CO2 levels, then even heroic efforts costing billions of dollars to reduce CO2 emissions might only slightly reduce warming. Maybe it’s better, then, accept that the world’s going to be warmer and spend the money protecting coastal areas, easing economic dislocations, etc.

    Anyway, I’m just trying to clarify the argument to which you’re responding. I have some sympathy for that point of view, but I’m here reading RealClimate because I know I don’t understand the science well enough to know just who has the right idea about what to do next.

    [Response:Release of fossil-fuel CO2 is not just a marginal source of warming to 2100, it is the main source. The warming forecast by the end of the century is caused by us, it’s not natural. It would be unprecedented in millions of years. Don’t confuse the present-day warmth with the forecast for the coming century. David]

  45. 45
    Roger Pielke, Jr. says:

    Josh Halpern- (#36)

    Do tell, what are the answers to these mysterious questions?

  46. 46
    Hank Roberts says:

    > To use an analogy, if your basement is flooding because water is coming is leaking
    > through the roof and seaping in through the cellar walls, and you have $200 to spend,
    > are you better off patching your roof or buying a sump pump?

    But the problem is the people uphill from you have gone on vacation and left their lawn sprinkler system on “full flood.”

  47. 47
    Eli Rabett says:

    I would refer the good Dr. Pielke here and there for the answers to his questions.


    [Response: Eli, Roger, Regardless of your disputes eleswhere, please confine your remarks here to on-topic scientific issues. Thanks. – gavin]

  48. 48
    James says:

    Re #44: You say “The point is that reducing global CO2 emissions only appears to be possible at a high economic cost.” That’s really at the heart of what we might call the denialist industry. Most of that high economic cost (the height of which is in my opinion greatly exaggerated) is going to fall mainly on a few industries that are heavily invested in current fossil fuels, so they support denialists to protect their investments.

    Of course, the smart ones seem to be hedging their bets. As someone remarked the other day, it’s amazing how many oil companies have solar-power subsidiaries :-)

  49. 49
    Charles Muller says:

    “There is an interesting dynamic at work. The denial crowd has become increasingly shrill to deal with the avalanche of science demonstrating the reality and bad effects of global warming.”

    Hum, reality of GW, no doubt. But reality of “bad effects” 1750-2006 is a more value-based point of view and the “avalanche” far less convincing. Take a precise example on this thread, the last Parmesan paper (link suggested at #35). She explains that because of GW, emperor penguins are at risk of extinction in Antarctic (false, they are not), apollo butterflies in Europe (false, they are not), harlequin frogs extincted in Central America (false, amphibian specialists know that chytrid fungus expansion from Africa, due to man, is the culprit since the 60’s, and not only in Costa Rica), and so on. This kind of false attribution / observation explains partly a skeptical reaction, in biodiversity or other fields. When Al Gore links West Nile Virus recent epidemy in North America to GW, do you know one epidemiologist who won’t object : guy, be careful, weak amplitude of recent temperature / humidity trends is a very very minor aspect of the infectious diseases ermergence problem, when compared to globalization for example?

    So, want to reduce the “denial crowd”? First reduce the always-more-catastrophist black picture. (Well, I’m French, maybe the US media are far more influenced by oil lobbies than in our nuclear nation, and it could partly explain our different perspectives on public perception of the problem. But anyway, if you misinterpret reality as scientist, you undermine science credibility. And feed the crowd).

  50. 50
    Hank Roberts says:

    Charles, harlequin frogs?

    What’s your source for your belief about that?
    How recently have you checked what you believe against current information?

    It appears you’re getting bad info and repeating it. Here’s my source.
    Do you have another source, that’s current?

    Harlequin frogs:

    Gavin, speaking of unstoppable hot air:

    — Would you all consider having some focused science topics in which comments would be more moderated heavily for helpful challenges, from which the rest of us could learn, by seeing some willing scientists think out loud and — even with hard argument — push one another to do better science.

    A kibitzer’s parallel forum could collect comments, and be a way to get the occasional truly helpful outsider’s comment (like the lawyer who spotted a typo in published work a while back).