RealClimate logo

Getting things right

Filed under: — gavin @ 20 January 2011

Last Monday, I was asked by a journalist whether a claim in a new report from a small NGO made any sense. The report was mostly focused on the impacts of climate change on food production – clearly an important topic, and one where public awareness of the scale of the risk is low. However, the study was based on a mistaken estimate of how large global warming would be in 2020. I replied to the journalist (and indirectly to the NGO itself, as did other scientists) that no, this did not make any sense, and that they should fix the errors before the report went public on Thursday. For various reasons, the NGO made no changes to their report. The press response to their study has therefore been almost totally dominated by the error at the beginning of the report, rather than the substance of their work on the impacts. This public relations debacle has lessons for NGOs, the press, and the public.

The erroneous claim in the study was that the temperature anomaly in 2020 would be 2.4ºC above pre-industrial. This is obviously very different from the IPCC projections:

which show trends of about 0.2ºC/decade, and temperatures at 2020 of around 1-1.4ºC above pre-industrial. The claim is thus at least 1ºC above what it should have been, and implied trends over the next decade an order of magnitude higher than otherwise expected.

How they made this mistake is quite instructive though. The steps they followed were as follows:

  • Current CO2 is 390 ppm
  • Growth in CO2 is around 2 ppm/yr, and so by 2020 there will be ~410 ppm

So far so good. The different IPCC scenarios give a range of 412-420 ppm.

  • They then calculated the CO2-eq to be 490 ppm.
  • The forcing from 490 ppm with respect to the pre-industrial is 5.35*log(490/280)=3 W/m2.
  • Given a climate sensitivity of 3ºC for 2xCO2 (i.e. 3.7 W/m2), a forcing of 3 W/m2 translates to 3*3/3.7=2.4ºC

The first error is in misunderstanding what CO2-eq means and is used for. Unfortunately, there are two mutually inconsistent definitions out there (and they have been confused before). The first, used by policymakers in relation to the Kyoto protocol, relates the radiative impact of all the well-mixed greenhouse gases (i.e. CO2, CH4, N2O, CFCs) to an equivalent amount of CO2 for purposes of accounting across the basket of gases. Current GHG amounts under this definition are ~460 ppm, and conceivably could be 490 ppm by 2020.

However, the other definition is used when describing the total net forcing on the climate system. In that case, it is not just the Kyoto gases that must be included but also ozone, black carbon, sulphates, land use, nitrates etc. Coincidentally, all of the extra GHGs and aerosols actually cancel out to a large extent and so the CO2-eq in this sense is quite close to the actual value of CO2 all on its own (i.e. in IPCC 2007, the radiative forcing from CO2 was 1.7 W/m2, and the net radiative forcing was also 1.7 W/m2 (with larger uncertainties of course), implying the CO2-eq was equal to actual CO2 concentrations).

In deciding how the climate is going to react, one obviously needs to be using the second definition. Using the first is equivalent to assuming that between now and 2020 all anthropogenic aerosols, ozone and land use changes will go to zero. So, they used an excessive forcing value (3 W/m2 instead of ~2 W/m2).

The second mistake has a bigger consequence: is that they assumed that the instantaneous response to a forcing is the same as the long-term equilibrium response. This would be equivalent to a planet in which there was no thermal inertia – or one in which there were no oceans. Oceans have such a large heat capacity that it takes decades to hundreds of years for them to equilibriate to a new forcing. To quantify this, modellers often talk about transient climate sensitivity, a measure of a near term temperature response to an increasing amount of CO2, and which is often less than half of the standard climate sensitivity.

It has to be acknowledged that people sometimes make genuine mistakes without having any desire to mislead or confuse, and that this is most likely the case here. It does no responsible organisation any good to have such a mistake in their material. It just leads to distractions from the substance of the report. The situation is serious enough that there is no need for exaggerated claims to produce headlines, just the plain unvarnished best guesses will be fine. It is likely that temperatures will reach 2.4ºC at some point in the next this century, and so the calculated impacts are certainly relevant – just not in 2020.

Unfortunately, in this case the people involved did not decide to fix the errors that were pointed out, going so far as to have the PR person for the launch insist that the calculation was ok. That the Guardian journalist, Suzanne Goldenberg, took the time to check on the details is a credit to the press. The reaction can be put down to institutional inertia, combined with the fact that their scientific advisor was in hospital (and is 87). It would clearly have been much better to have had this properly peer reviewed ahead of time. To that end the AGU Q&A climate service or the Climate Science Rapid Reaction Taskforce (CSRRT) are invaluable resources for getting some quick scientific peer review.

107 Responses to “Getting things right”

  1. 51
    Girma says:


    In your formula for the forcing, I think the logarithm function is ln, not log.


  2. 52
    Edward Greisch says:

    Gavin’s response to 40: Be careful with sarcasm. Somebody could take you literally.

  3. 53
    GlenFergus says:

    2020 is now so close that if you wanted a decent temperature estimate, there’s really no need for science. The data are so well behaved that a straighforward trend extrapolation is pretty convincing. That gives about 0.8°C above 1951-1980, or about 1.1°C above pre-industrial.

  4. 54
    Girma says:


    If the global mean temperature anomaly for 2020 is not 2.4 deg C, what is your “unvarnished best guess”?

  5. 55
  6. 56
    Andy Gates says:

    So, just applying the unscientific squint-n-thumb against the IPCC projections chart, the bad stuff they’re talking about would come in as early as 2070 (from the A2 scenario), right?

    Is the bad stuff new in its badness? Because 2070 isn’t that far away either.

  7. 57
    Didactylos says:

    My own take on this “guilt” issue is that this NGO (the report was written by the Executive Director) are well meaning, and honestly believe (as many do here) that reality will turn out far worse than IPCC projections.

    That’s clearly why they tried to come up with their own estimate, and simple incompetence led them to a number they thought perfectly plausible.

    When the error was pointed out to them, there were a few things holding them back from rushing out and changing it. First, they already distrust IPCC estimates. Being told their calculation is “wrong” isn’t going to be taken on faith, and other reports of the error are nowhere near as clear as Gavin’s explanation.

    Then there’s the purely egocentric dislike of being shown to be wrong. It happens to scientists, too, but so much more to activists driven by a burning internal certainty.

    The simple practicalities are also a problem. If there are paper copies out there, clawing them back isn’t an easy matter. Clawing something back from the Internet is even harder. And this isn’t something that can be fixed with a correction. Even the title of the report is wrong!

    I hope I don’t need to make explicit the dangers of over-egging the omelette. Consider this an object lesson.

  8. 58
    Jim Eaton says:

    I appreciate climate scientists taking the high road.

    When I was running a conservation organization, I had staff that could not understand why I demanded that anything they wrote was based on solid science. “But the other side constantly lies, so why shouldn’t we stretch the truth since we are on the good side!” I patiently explained that in the long run, good science would triumph over the fabricators.

    Considering the current House of Representatives, my advise might be called into question. But my science background convinces me that good scientists must point out errors that might falsely bolster their case, because in the long run, good science will prevail. I just hope that the policy makers somehow will understand how good science works and make appropriate decisions. These next few years are going to be quite trying.

  9. 59
    Slioch says:

    Lord Blagger

    Here’s a simple (OK, simple minded) thought experiment that might prove useful.

    Take a large bucket of cold water in a cold room and stick a lit candle under it. You might notice that the initial response is an increase in temperature of about 0.02C per hour and that after about 30 hours or more the water in the bucket more or less equilibrates at a temperature a few degrees above what is was originally. You monitor the temperature continuously and you get a nice smooth graph. That’s the earth with just CO2 forcing (OK, strictly the candle should be getting slightly brighter with time, but let’s forget about that).

    Then repeat the experiment, but this time occasionally chuck in a few ice cubes: that’s a big volcano blowing off or a La Nina. Or stick in a small electric immersion heater for a few minutes: that’s an El Nino. You monitor the temperature continuously and this time, of course, the graph is up and down a lot – but you still get eventually to an equilibrium temperature the same few degrees above what you started with.

    Does the fact that the ice cubes and immersion heater cause much more rapid temperature changes than our poor little (but relentless) candle negate the fact that, relative to the candle, the thermal inertia of the bucket of water is enormous? No, of course it doesn’t.

  10. 60

    LB 37: The problem with CO2 claims is that you can’t separate out the CO2 effect from a rise in temperature from natural variation.

    BPL: You’ve never heard of “Analysis of variance,” have you?

    P.S. Gavin et al. — the Captcha with some outlined areas is even harder to read than the last one.

  11. 61
    J Bowers says:

    Getting wrong things corrected: Canada Free Press apologises to Dr Andrew Weaver for Tim Ball’s article entitled “Corruption of Climate Change Has Created 30 Lost Years”.

  12. 62
    Lord Blagger says:

    [Response: Nonsense. You’ve just assumed some magical ‘natural variation’ that you contend is warming the planet. Cooling or warmings have (to first order) the same inertia associated with them. – gavin]

    No. That’s why I focused solely on the cooling periods. I’m not the one putting forward anything about the cause of cooling or warming. You are.

    [Response: Than what? Where is your estimate of what would happen with a much smaller heat capacity? – gavin]


    You’ve put forward the proposition that there is part of the environment that has huge heat capacity. I agree with that part.

    You then say that heat capacity produces inertia in the environment.

    Next in your chain is that because we have warming caused by CO2, that inertia is masking the effect of that warming.

    However, the flaw is that we have periods based on graphs from this blog that show 1C over 3 year falls.

    Now that’s either because

    1. temperature measurements have huge error bars and random measurement errors
    2. The inertia in warming the thermal mass doesn’t have the masking effect that you claim.

    You can’t have a large inertia and rapid variation in temperatures. The two are contradictory.

    A large block of metal will not change its temperature rapidly. Very straightforward physics easy to demonstrate.


    [Response: Go on then, demonstrate mathematically that the rate of change of temperature in a system with a heat capacity is bounded, regardless of the strength of the forcing. It will be fun to see. – gavin

  13. 63

    “P.S. Gavin et al. — the Captcha with some outlined areas is even harder to read than the last one.”

    True, that–and the damned thing froze last time when I tried for a new challenge, which is something that never happened before. Luckily, I still guessed right, and had copied the comment anyway just in case, but it was annoying.

    (No Problems this time, though–“seale puticar” it is.)

  14. 64
    Lord Blagger sez says:

    Re: [Go on then, demonstrate mathematically that the rate of change of temperature in a system with a heat capacity is bounded, regardless of the strength of the forcing. It will be fun to see.]

    Gavin, that’s not fair! It’s my job to bloviate and toss around false analogies while holding you to a standard of mathematical precision if not certainty.

    Plus, I can’t do the math…

  15. 65
    MightyDrunken says:

    As a comparison the Institution of Mechanical Engineers have released a report on feeding the world with 9 Billion people called “One planet, too many people?”.

    The general conclusion is that with current technology, properly implemented, we can feed 9 billion. To me it seems a bit optimistic and does not really address the problems of water and soil fertility problems, for example.

  16. 66

    The questions that I keep coming back to are: “What was so important about the date on which the report was released that it could not have been changed in order to allow the author to review the scientists’ concerns?”; “Why did this obscure NGO use a New York PR firm to release its report?”; “Where did the NGO get the funds to pay the PR firm?”; and “How can we get access to their financial reports?”

    Until I see answers to these questions, I guess I’ll just have to suspend judgment.

  17. 67
    Didactylos says:

    Dear friends, I think you are missing something important.

    Blagging: “To convince another person that all the stuff you just made up is in fact true and worthy.” [From French blaguer, to talk through one’s hat]

    (There are other definitions, but this is the one that is appropriate here.)

  18. 68
    Hank Roberts says:

    > You can’t have a large inertia and rapid variation
    > in temperatures. The two are contradictory.

    I recommend learning to cook. It will help you more than theory does.
    Or going swimming in a deep lake on the first hot day of summer.

  19. 69
    Ray Ladbury says:

    Lord Blagger,
    Are you interested in learning anything, or do you simply want to bloviate in ignorance. If you want to learn something, then please, please, please go visit Tamino’s blog. There you will find that different forcings have different lag times and that you cannot treat the climate system as a simple continuous heat reservoir.

    Otherwise, bloviate away. It’s very interesting seeing the Dunning-Kruger effect made flesh.

  20. 70
    dhogaza says:


    The questions that I keep coming back to are: “What was so important about the date on which the report was released that it could not have been changed in order to allow the author to review the scientists’ concerns?”

    Stephen Leahy saw it when it was embargoed, i.e. had been given out with a release date a few days in the future.

    The person in charge of the release may’ve simply thought that given the lengthy preparation and review process, and the work having been vetted by their in-house authority, and his being hospitalized and perhaps not available or perhaps simply not wanting to bother him while he was in the hospital, that the criticisms were wrong.

    Or they didn’t want to make an embarrassing decision (chasing down everyone who had an embargoed copy asking them not to publish it).

    “Why did this obscure NGO use a New York PR firm to release its report?”

    Perhaps because they’re from argentina, english isn’t their first language, and they have limited experience dealing with the international press? PR firms aren’t necessarily all that expensive for doing routine stuff like pumping out PRs to the press, it’s pretty much automated these days …

    “How can we get access to their financial reports?”

    If they were a US NGO, their financial reports would be publicly available, by law. I have no idea if that’s true or not in Argentina.

  21. 71
    Brian Dodge says:

    “The general conclusion is that with current technology, properly implemented, we can feed 9 billion.” MightyDrunken — 21 Jan 2011 @ 10:17 AM
    “In the 1990s, it was calculated that some 4.3 billion large domesticated animals and 17 billion poultry eat 40 per cent of the world’s grain supply.”

    If we all become vegan, feeding us will be a piece of cake, right?

    The phrase “properly implemented” glosses over the political[1], social[2], and economic[3] difficulties facing the world in providing enough food for everyone. The FAO states that in 2010, 925 million went hungry, and that every six seconds, a child dies of a hunger related disease. So far, “properly implemented” isn’t working out so well.

    [1](should the US use its food exports to manipulate world politics like OPEC has used oil exports?)
    [2](“Since higher status conventionally is associated with greater meat and fat consumption, such dietary change challenges traditional social, as well as nutritional, beliefs and practices and may prove difficult.” ibid)
    [3](the US exported $4.3 billion pork, $4.2 billion chicken, and $3.1 billion beef in 2009 –

  22. 72
    simon abingdon says:

    #69 Ray Ladbury

    Ah yes, the Dunning-Kruger effect. W.B.Yeats put it concisely thus: “The best lack all conviction, while the worst are full of passionate intensity.”

  23. 73
    CM says:

    Tenney #66,
    following the link from the OP, you’d find that the president of the US branch of the NGO is also the founder of the PR firm, which specializes in this sort of thing, and has a mission statement about improving the lives of the world’s underprivileged etc. It’s not all that suspicious.

  24. 74
    intensional says:

    The graph is incomprehensible because none of the alphanumeric-labeled graphics are explained. Why not?

    [Response: Please see the originating page – gavin]

  25. 75
    russwylie says:

    @69 ray ladbury
    are you replying to 64 “Lord Blagger sez” or the ‘real’ “Lord Blagger” eg #62 ?
    and please , fake lord blagger ( oh the irony of a fake Pseudonym), grow up. this is supposed to be a science blog.

  26. 76
    David B. Benson says:

    Girma @54 — If you would actually study this simple model
    your question would be answered.

  27. 77
    Joe Cushley says:

    Russ Wylie @ 75

    “this is supposed to be a science blog”

    And how much science has the ‘real’ Lord Blagger brought to the table?! Lighten up.

  28. 78

    #75, russwylie: My apologies for the puerile attempt to bait Lord Blagger into actually doing the math. No more false pseudonyms for me!

    Where did the “real” Lord Blagger go, anyway? We await your response…

  29. 79

    This is interesting. I just revised & resubmitted a paper on “Food Rights, Food Frugality, and Climate Change.” I threw in a “2.4C” figure (in the mix of many points), but it was from Ramanathan & Feng (2008), about the equilibrium of the GHGs we’ve already emitted, even if we were to stop emitting today. (And I’m thinking that 2.4C seems to not be equilibrium, since it may trigger massive outgassing from hydrates & permafrost — sort of like us poking and waking a sleeping world-destroying dragon with our puny emissions).

    The point is it doesn’t matter WHEN the harms to the poor & our progeny from ACC kick in — I didn’t dwell on time frames — we are guilty and culpable NOW.

    I also discussed rights theory, and how the West (per capita the highest emitters) mainly follows a “rights-based code of ethics,” which privileges one’s own rights and discounts & dismisses duties to others and their rights (as opposed to a “duty-based code of ethics,” which makes others and duties to them paramount), and this causes us a sociocultural blockage to becoming ecological citizens and doing the right things to mitigate climate change.

    I discussed how food production also contributes to ACC, and in line with Marx’s conceptualizing products as containing the workers’ blood, sweat, and labor, I suggested that food contains not only nourishment, and health problems our “food police” family and friends chide us about, but also harm to the environment and the starving peoples of the world on into the future through CC.

    Hopefully the glitch in the Food & CC study referred to here won’t derail my paper’s publication. As it is, I had to include in this last version discussion of the IPCC & its mistakes (which I had not even quoted in my original draft — the 2035 glacier thing on p. 493 of Asia in WGII — bec I thought it too extreme & the sources too weak, even before the error was caught).


    Ramanathan, V., and Y. Feng. 2008. “On Avoiding Dangerous Anthropogenic Interference with the Climate System: Formidable Challenges Ahead.” PNAS 105.38: 14245-14250.

  30. 80
    S. Majumder says:

    Could someone please find the catch in this article :

    Here one very eminent scientist is claiming about 40% contribution of cosmic radiations on global warming. I do understand that this report could be an attempt from the environment ministry of India to reduce the immense pressure on them to act on global warming.

    I am not a climate expert. But I do feel that something is missing in this report.

    — Soumitra

  31. 81
    CM says:

    Lynn (#79),

    Just curious: Was it a reviewer that required you to discuss errors in the IPCC report, and why? From your description of your paper, it’s not clear that it would be pertinent; one might think the reviewer had a political axe to grind, or understood rather less of the Himalayagate coverage than yourself.

    On a different note [and an off-topic one, but, in the interest of “getting things right”, here goes]: The idea that

    a “rights-based code of ethics” … privileges one’s own rights and discounts & dismisses duties to others and their rights (as opposed to a “duty-based code of ethics,” which makes others and duties to them paramount)

    seems conceptually muddled. A rights-based ethics requires that I not only demand my own rights, but by the same token that I also respect yours, that I recognize the limits of my rights when they clash against yours, and that I carry out those duties to you that your rights against me may entail. It’s a hypothesis I think would quickly go “poof” if tested either against actual representative examples of such codes the Universal Declaration of Human Rights.

    But if you have actual evidence for this, or for other arguments to support the proposition that a rights-based ethics is somehow a significant impediment to doing the right thing for the environment, I would be genuinely interested in references [to the extent moderators permit this digression].

  32. 82

    OK, thank you all for the information. I will try to accord the NGO and the PR firm the benefit of the doubt.

    That leaves the amazing behavior of the people in charge of Scientific American, who prominently displayed a very non-scientific report on their website, and who took the report down when informed by a number of people of the glaring error, and then subsequently put the report back up on their site again.

    How weird is that? I am at a loss to come up with a reasonable motive.

  33. 83

    Tenney, The Sci Am story by Beillo is a correction of sorts although it contains several errors.

    The original post is a climatewire piece they picked up which now carries a pretty tame editor’s note… It seems because the study wasn’t withdrawn by the NGO, Sci Am isn’t going to drop the story.

    I agree that is weird, and kinda dumb – it’s not like the study was published in a journal.

  34. 84
    Deep Climate says:

    Sorry to obsess about CO2e.

    But I think it’s worth setting the record straight there too.

    I’ve looked at the study, and as far as I can tell there is no calculation or reference for how the 490 CO2e ppm level in 2020 was derived from projected 410 CO2 ppm.

    In fact at p. 6 we have:

    The level of concentrations of all GHGs combined reached 375 ppm CO2-eq in 2004. Current
    levels are estimated at 387 ppm CO2-eq.
    Current increase rates of CO2 are about 0.5 percent per year. By 2020, CO2 concentrations would
    reach, at least, a level of 410 ppm. These levels of CO2 would correspond to GHGs concentrations
    above 490 ppm CO2-eq.

    The accompanying chart shows “CO2-eq” and has it rising from 387 in 2008 to 490 in 2020! Massive confusion reigns.

    Anyway, I’d still like to know where CO2-eq is now and how fast it is projected to rise. The information I’ve seen suggests it should be about 45 ppm higher than CO2, and is rising at or a little below the CO2 rate of increase (see #49 above).

    I would think the latest SRES scenarios would answer this question, at least implicitly. (Thanks in advance to Gavin or whoever else wants to take this on).

  35. 85
    Julie K. says:

    Apart of what had been written here we still don´t understand the real impact on the environment. Any mistakes in scientist’s institutions cannot be forced. We (and scientists as well) don´t know how to treat these information. We are on the crossroad now and have to decide which way to go. And as we don´t have any previous experiences we have to rely on provable research. Let´s stipulate different figures in various models that can bring some scenarios. That is nothing wrong with that.

  36. 86

    Hi CM (#81), both reviewers and the editor actually liked the paper & thought it would be informative to the readers in that social science journal about food (it would be the 1st on CC).

    I think the point is, most people don’t really follow climate change science and skeptic arguments much … they just pick up a few things about it from the media, and the IPCC fiasco was something they picked up. Even though I relied mainly on individual studies (some of which I found thru the IPCC), only quoting the IPCC directly in a few places, they thought for the sake of the readers, who would not be following the science & “counter-science,” that I should make clear the validity of the IPCC & point out any IPCC shortcomings or errors that might impact my study. So I added an endnote referring to the Netherlands Environmental Assessment Agency review of the IPCC, and how it supported the validity of the IPCC. In the process of looking at that report I did find another minor problem in the IPCC re clarity, and reworded a passage in my paper, adding “which in drought years” to:

    With climate change increasing the risk of droughts, some countries in Sub-Saharan Africa — especially in the Sahel, East Africa, and southern Africa –- could face substantial reduction in their rain-fed crops, which in drought years are reduced by up to 50 percent (Parry, et al. 2007: 48).

    RE the rights discussion, this is used more from a social science perspective of how people in societies that have “rights-based codes of ethics” might differ in their thinking & behavior from people in societies that follow “duty-based codes of ethics.”

    Supposedly we (following a rights-based code) would be also concerned about other people’s rights, and many good people are, but we tend more to focus on our own rights. It’s sort of a matter of attribution theory kicking in, a discounting of the other, esp outgroup people.

    A recent example, I was at a religious retreat last week & I told them about another paper I wrote re the much lower crime and recidivism rate in India than in the U.S., in part bec they follow more a duty-based code (dharma), and studies have found that Indian prisoners tend not to know they have rights, and tend not to feel they deserve rights, certainly not at the level as in the U.S.

    Later someone brought up how Brownsville, TX had just instituted a 25 cent fee on all shopping bags (the money to be used for green projects), and the people at the table got all huffy and incensed about it, and told how the residents were really upset about it. To which I mumbled that people should have been bringing their own bags for the past 20 years, and how profligate our society was; I mentioned how local, regional, and global environmental harms are killing people, etc; and that the students in the Environmental Awareness Club would be tickled pink about that new ordinance.

    One lady brought in our earlier discussion….”Yes, see, we are so focused on our own rights; we think we have a right to free shopping bags.”

    Same with people who are working to get institutional menus in hospitals and universities changed to reduce meat or offer vegetarian meals (to help the environment), and how people are resisting this, claiming individual rights violations, etc.

    And we all know the denialists are very concerned that their rights are going to be infringed upon if we do anything to mitigate climate change, without a thought to the harm we are causing others…thereby infringing on their rights. It seem to them other people’s rights aren’t nearly as important as their own rights.

  37. 87
    John McCormick says:

    RE # 66 and # 67

    Tenny, you asked the right questions. I found it a bit much the group hired a NYC PR firm.

    I wonder if there is a connection between the NGO and Didactylos’ definition of blagging and persons and institutions that blag.

    More questions about the NGO and its motive. But, Gavin asks that we do not attribute motives or suggest motives. Easier said.

    That a colleague was not in a position to give full attention to the content of the report and should have been all over it sounds irresponsible. That something deeper and less charitable may have occurred is worthy of consideration

    John McCormick

  38. 88
    Hank Roberts says:

    SciAm, as of right now, notes:

    “Editor’s Note: This story from Climatewire is informed, in part, by a press release that was subsequently retracted by the online news service of the American Association for the Advancement of Science (AAAS). The study itself has not been retracted. It presents an aggressive scenario for future warming under climate change that many climate scientists question. We will publish an Observations blog post later this afternoon to offer more background on the issues surrounding this story.”

  39. 89
    Mike Roddy says:

    Good article, but do we need to keep using IPCC IV as the default? Indications are clear that their predictions about sea level, ice, and fossil fuel burning are way too low. The 2020 temperature estimate may not be far off, but at some point more recent work needs to be accounted for in summaries such as this one.

  40. 90
    jeannick says:

    Reading through , three points and one comment spring to mind

    The comment is that even if the authors stuffed it for 2020
    ( and deserve some canning for it )
    the main point remain ,
    what would be the consequences of a global 2Dg rise on world food production .

    First point :
    There is no mention of nutrients , especially the massive emissions of growth friendly chemicals , CO2 , Sulfur and Nitrous oxides

    Second :
    The assumption of the tropics globally drying is suspicious
    a rise in temperature would see higher atmospheric water content
    a global increase in precipitation would be intuitive ,
    Anecdotal evidence certainly would tend this way

    Third : a raising of the permafrost line would free very large amount of arable land in the northern hemisphere

  41. 91
    Richard Simons says:

    jeannick says:
    25 Jan 2011 at 4:55 PM

    Third : a raising of the permafrost line would free very large amount of arable land in the northern hemisphere

    Where? Certainly not in Canada, where most of the land that is currently too cold for crop growth consists of rock, possibly covered with a few centimetres of soil, swamps and lakes. I suspect the same is true of Russia.

  42. 92
    Hank Roberts says:

    Jeannick, where did you find a source saying CO2, sulfur, and nitrous oxide are “growth friendly chemicals” — citation needed. I’d guess your source wasn’t talking about plant growth but about profitability in a business.

  43. 93
    Ray Ladbury says:

    [edit – please stick to arguments on substance, Thanks.]

  44. 94
    John Pollack says:

    Interesting citation, Ray!

    Concerning food production, part of the hazard has to be changing ocean currents and SSTs, due in part to changing freshwater fluxes including melting glaciers. This provides a mechanism for abrupt climate change coordinated by oceanic teleconnections. The YD is a classic example, but there will undoubtedly be some surprises in a warmer world, too.

    Coordinated climate changes imply that farmers in many parts of the world see unusual weather for their area, and have a poor harvest. It would take quite a while to conclude that the old weather isn’t coming back, and the farmers need to make expensive investments in new equipment and seed.
    By then, another change could be on the way.

    It’s not enough to say that when it warms, farmers will just grow soybeans in Manitoba instead of Ohio, even if the soil allows it. They will have to have sufficient confidence that things are reliable enough to plant and harvest soybeans, rather than, say, canola.

  45. 95
    Deep Climate says:


    Still not sure what happened to get from 387 Co2-eq now to 490 CO2-eq in 2020. Maybe they confused the two kinds of CO2-eq (i.e. the first is total forcings and the second is “Kyoto 6”).

    And I suppose it’s the “total forcings” CO2-eq that counts anyway.

  46. 96

    RE #90 & “CO2 is good for plants,” something from my paper:

    “First we need to address the argument that elevated carbon dioxide levels increase crop production. Aside from this being disingenuous because the CO2 is also causing warming and other effects that could be harmful to crops, there is some evidence that increasing CO2 will not help crops much, and even harm them and sea life, never mind the warming (Cline 2007: 23-26). While earlier enclosed studies showed increased growth with added CO2, recent open field studies show less increase and even a decline of some crops (Long, et al. 2006, Cruz, et al. 2007: 480). Furthermore, crops were found to be less nutritious (Högy, et al. 2009), and had greater pest damage (Hunter 2001). In the real world, crop growth is dependent on and affected by many factors beyond CO2, including other nutrients, water supply, climate, extreme weather events, soil moisture, toxins expected to increase with global warming, and soil acidification from CO2 emissions (Oh and Richter 2004). So while CO2 may moderately enhance crops up to a point, these other factors are expected to limit the potential enhancement and even lead to eventual declines. When the impact of warming is considered, a nonlinear relationship regarding crop productivity has been found for mid and high latitudes — the U.S., Canada, Europe, Russia, Japan and Northern China — with increased yields projected up to around 2050, after which the warming causes sharp decrease (Schlenker and Roberts 2009; Parry, et al. 2007: 74). As for sea life, an important human food supply, CO2-caused ocean acidification is having negative impacts on zooplankton (at the base of the food chain), shellfish, fish, and coral reefs, home to one-fourth of sealife (Doney, et al. 2009; Hoegh-Guldberg, et al. 2007; Munday, et al. 2010).”

    And from an earlier version (I had to cut like crazy): “A study in Japan showed that doubled CO2 could decrease rice yield by up to 40% through floret sterility (Cruz, et al. 2007: 480).”

    So much for “CO2: We call it life.”
    *Cline. 2007. Global Warming and Agriculture.
    *Cruz, et al. 2007. “Asia.” Climate Change 2007: Impacts, Adaptation and Vulnerability. Contributions of WGII to 4AR of IPCC.
    *Doney, et al. 2009. Ocean Acidification: The Other CO2 Problem. Ann Rev of Marine Sciences 1: 169-192.
    *Hoegh-Guldberg, et al. 2007. Coral reefs under rapid climate change and ocean acidification. Science 318: 1737-1742.
    *Högy, et al. 2009. “Effects of elevated CO2 on grain yield and quality of wheat: results from a 3-year free-air CO2 enrichment experiment.” Plant Biology 11: 60-69.
    *Hunter. 2001. “Effects of Elevated Atmospheric Carbon Dioxide on Insect-Plant Interactions.” Agricultural & Forest Entomology 3: 153-159.
    *Long, et al. 2006. “Food for Thought: Lower-Than-Expected Crop Yield Stimulation with Rising CO2 Concentrations.” Science 312.5782: 1918-1921.
    *Munday, et al. 2010. “Replenishment of fish populations is threatened by ocean acidification.” PNAS 107(29):12930-12934.
    *Oh & Richter. 2004. “Soil acidification induced by elevated atmospheric CO2” Global Change Biology 10.11: 1936-1946.
    *Parry, et al. 2007. “Technical Summary.” In 4AR IPCC.
    *Schlenker & Roberts. 2009. “Nonlinear Temperature Effects Indicate Severe Damages to U.S. Crop Yields under Climate Change.” PNAS. 106.37: 15594-15598.

  47. 97

    RE #90 & 2nd point, more WV.

    I think this could actually be a problem, because it may lead to more floods, even during droughts. Most plant roots need oxygen, and die in standing water.

    Also this year (I’m in the substropics of South Texas) we are experiencing severe fungal problems on our garden crops & loss of produce….it seems from the increased moisture in the air.

    Don’t know if that’s been studied.

  48. 98
    Deep Climate says:

    It looks like Richard Lindzen makes similar mistakes (confusion between “Kyoto” and “total forcing” CO2-eq, and between current and eventual equilibrium warming) in his piece for the GWPF.

    According to the UN’s Intergovernmental Panel on Climate Change, the greenhouse forcing from man made greenhouse gases is already about 86% of what one expects from a doubling of CO2 (with about half coming from methane, nitrous oxide, freons and ozone), and alarming predictions depend on models for which the sensitivity to a doubling for CO2 is greater than 2C which implies that we should already have seen much more warming than we have seen thus far, even if all the warming we have seen so far were due to man. This contradiction is rendered more acute by the fact that there has been no statistically significant net global warming for the last fourteen years.

    Except no one on the contrarian side has bothered to correct him, at least so far.

    [h/t MapleLeaf at DeepClimate]

  49. 99
    Hank Roberts says:

    Another problem with growing some plants further north — day length.

  50. 100
    Deep Climate says:

    Hmmm … that Lindzen piece in GWPF (see #98) goes back to 2008. I found this version from February 2008.

    It appears to be pretty well identical and has the same bottom line claim that “we should already have seen much more warming than we have seen thus far, even if all the warming we have seen so far were due to man”.

    Three years on … where are the auditors when you need them?