Are Scientists Too Conservative About Climate?

November 2, 2014

Why the IPCC is a very conservative document, above, from my interview with Stefan Rahmstorf, last year in Reykjavik.

Chris Mooney  in Washington Post Wonkblog:

On Nov. 2, the United Nations’ Intergovernmental Panel on Climate Change will release its “Synthesis Report,” the final stage in a yearlong document dump that, collectively, presents the current expert consensus about climate change and its consequences. This synthesis report (which has already been leaked and reported on — like it always is) pulls together the conclusions of three prior reports of the IPCC’s 5th Assessment Report, and will “provide the roadmap by which policymakers will hopefully find their way to a global agreement to finally reverse course on climate change,” according to the IPCC chairman Rajendra Pachauri.

There’s just one problem. According to a number of scientific critics, the scientific consensus represented by the IPCC is a very conservative consensus. IPCC’s reports, they say, often underestimate the severity of global warming, in a way that may actually confuse policymakers (or worse). The IPCC, one scientific group charged last year, has a tendency to “err on the side of least drama.” And now, in a new study just out in the Bulletin of the American Meteorological Society, another group of researchers echoes that point. In scientific parlance, they charge that the IPCC is focused on avoiding what are called “type 1” errors — claiming something is happening when it really is not (a “false positive”) — rather than on avoiding “type 2” errors — not claiming something is happening when it really is (a “false negative”).

The consequence is that we do not always hear directly from the IPCC about how bad things could be.

By the year 2100, the leaked draft report claims, sea level rise “will likely be in the ranges of 0.26 to 0.55 m for RCP2.6 and of 0.45 to 0.82 m for RCP8.5 (medium confidence),” which is quite similar to what earlier documents from this round of the IPCC’s work have said. To translate: For two different scenarios for future greenhouse gas emissions — one a low end scenario, one a high end one — there is a 66 percent probability that sea level rise will fall into these two corresponding ranges. And the high end of the range, in the high end emissions scenario, is .82 meters of sea level rise, or 2.69 feet.

Alas, it turns out that these numbers are misleading in several ways — and may very well be too low. First, .82 meters is not actually the amount of sea level rise that is expected at the year 2100. If you sift carefully enough through the IPCC’s various reports, you will learn that it is rather the mean increase expected between the years 2081-2100, or during the last two decades of this century, when compared with the mean sea level between 1986 and 2005. The actual high end number for 2100 is .98 meters, or 3.22 feet – an amount that “would threaten the survival of coastal cities and entire island nations,” writes climate expert Stefan Rahmstorf of Potsdam University.

But it gets more complicated still — that’s not really the high end number either! Note above that IPCC only gives the range for sea level rise that it considers “likely.” What that means, according to Princeton’s Anderegg, is that “these ranges are only the middle 2/3 of the probability distribution.” In other words, he says, “there is a 17 percent chance it could be lower than that, and a 17 percent chance it could be higher than that.” You’d have to be pretty attuned to figure that out, though.

James Hansen,  “Scientific Reticence and Sea Level Rise” 2007:

I suspect the existence of what I call the ‘John Mercer effect’. Mercer (1978) suggested that global warming from burning of fossil fuels could lead to disastrous disintegration of the West Antarctic ice sheet, with a sea level rise of several meters worldwide. This was during the era when global warming was beginning to get attention from the United States Department of Energy and other science agencies. I noticed that scientists who disputed Mercer, suggesting that his paper was alarmist, were treated as being more authoritative.

It was not obvious who was right on the science, but it seemed to me, and I believe to most scientists, that the
scientists preaching caution and downplaying the dangers of climate change fared better in receipt of research funding.
Drawing attention to the dangers of global warming may or may not have helped increase funding for relevant scientific areas, but it surely did not help individuals like Mercer who stuck their heads out. I could vouch for that from my own
experience. After I published a paper (Hansen et al 1981 ) that described likely climate effects of fossil fuel use, the
Department of Energy reversed a decision to fund our research, specifically highlighting and criticizing aspects of that paper
at a workshop in Coolfont, West Virginia and in publication.(MacCracken 1983).

I believe there is a pressure on scientists to be conservative. Papers are accepted for publication more readily if they do not push too far and are larded with caveats. Caveats are essential to science, being born in skepticism, which is essential to the process of investigation and verification. But there is a question of degree. A tendency for ‘gradualism’ as new evidence comes to light may be ill-suited for communication, when an issue with a short time fuse is concerned

15 Responses to “Are Scientists Too Conservative About Climate?”


  1. […] Why the IPCC is a very conservative document, above, from my interview with Stefan Rahmstorf, last year in Reykjavik. Chris Mooney in Washington Post Wonkblog: On Nov. 2, the United Nations' Inter…  […]

  2. jimbills Says:

    I’m watching the media today. cnn.com runs the IPCC report with the leader headline, “Urgent Warning on Climate Change”.

    That article has the headline of “Invest now or face ‘irreversible’ effects of climate change, U.N. panel warns” in the actual article. Well, we are investing now.

    It starts, “The cost of fighting climate change will only climb if industrialized nations don’t take steps to reduce greenhouse gas emissions, the United Nations’ panel on the matter warned Sunday in its wrap-up report.”

    It’s framing the issue as an economic problem, which to me is a complete misunderstanding of the problem. But, it gets worse from here….

    foxnews.com has the story buried in their latest headlines, reading, “Climate change is your fault, UN reports says” (I’m not joking). abcnews.com has it also buried in their latest headlines, reading “UN Climate Report Offers Stark Warnings, Hope”. Both the abcnews.com and foxnews.com articles are the same article from the AP.

    bbc.co.uk leads it with the headline “Fossil fuels must go by 2100 – IPCC”. That article starts with:

    “The unrestricted use of fossil fuels should be phased out by 2100 if the world is to avoid dangerous climate change, a UN-backed expert panel says.

    The Intergovernmental Panel on Climate Change says in a stark report that most of the world’s electricity can – and must – be produced from low-carbon sources by 2050.”

    I think a lot of people will read that and think there’s no problem, then. We’ve got plenty of time! If the IPCC is being too conservative in their report (which seems to me a near certainty), their message is being watered down further by the media.


  3. Repeat to yourself until it all makes sense:

    Its the best report money can buy.


  4. Remember all that fuss when a mistake in one of the IPCC reports said that the Himalayan glaciers would be gone completely by 2035?

    http://www.skepticalscience.com/IPCC-Himalayan-glacier-2035-prediction.htm

    In the scheme of things, a pretty small mistake. Yet conservatives seized on it and had a field day denouncing the IPCC as being staffed with alarmists, lunatics, environwackos, doomers, communists, sex perverts, etc etc. The implication is that if the IPCC makes one mistake, then everything they say is utter nonsense, or more likely a sinister plot against America, motherhood, apple pie and the Bible.

    So it’s hardly surprising that the IPCC has learned to err on the side of conservatism. Every single sentence in their reports has to be checked and double-checked to avoid a repeat of “Glaciergate.” Even these conservative reports are going to be harshly criticized for being too alarmist.

    As far as “confusing the public” with their conservatism, I honestly don’t think the public even knows what the IPCC is. If they get their information from Fox News or AM hate-talk radio, they probably think it’s an abbreviation for “International Party of Communist Criminals.”

  5. omnologos Says:

    There are more than 1 million words in English. There must be one better suited to explain what you mean than “conservative” (see how Cy uses it nonchalantly in the political sense).

    Also Google reports among the synonyms: “3.

    (of an estimate) purposely low for the sake of caution. synonyms:low, cautious,  understated, unexaggerated, moderate,reasonable

    Note how few or none of those words have a generally negative connotation. IOW there’s no point in blaming the media for watering down an already confused message.

    • dumboldguy Says:

      H-e-e-e-e-r-e-s OMNO!

      And although I don’t want to encourage him too much, he makes some small bit of sense here. Cy is not using the word conservative “nonchalantly” in the political sense here, though. He is right on the money to use it in the political sense because that is our root problem—-the loooney-tune political conservatives have so politicized the issue that the science has been obscured in horsepucky. The scientists are going beyond their natural “conservatism” as Omno’s synonyms describe and are running scared to the point that they can be called timid, fearful, and so afraid of being attacked that they are understating the science.

      No warrior ever took a hill by hiding behind rocks at the bottom and worrying about getting shot at on the way up, or by shooting less on the way up in the hopes that the enemy would do the same. We are in a war here and the scientists need to realize that. There is a “watered down and confused message” partly because the scientists have allowed the denier echo chamber and the media too much leeway in shaping the issue (both of which are owned by “conservatives”).

      When things always turn out worse than predicted, as have so many aspects of AGW, what’s the downside to being less “conservative”? The deniers are not “conservative” in their lying and obfuscation, and that needs to be countered by more scientists saying “Bad s**t is likely to happen, here it is, this is what it means, and if we don’t do something about it soon, we’re F**Ked”. Remember the reaction to Dr. Box’s comment. Bill Nye the Science Guy needs to start upping his game that way—-imagine the PR the cause would get if Bill dropped an occasional F-bomb.

      We have gone beyond the making of simple mistakes like Glaciergate and now have much truth to share about Arctic sea ice, Antarctic ice sheet, CO2, temperature, and sea level rise situations that are turning out to be worse than the “conservatives” predicted. Why are we so afraid to say “As in the past, it’s likely to be worse than what we predict”, and push the dialogue out towards those worst cases? Is the downside is that some denier may say ten years from now “You exaggerated”? No, the downside is that we will lose ten years, and once the SHTF it may be too late.

      (and I would dearly love to slap the s**t out of anyone who says “…while no single event can be attributed to global warming….” because they’re being “conservative”)

      • omnologos Says:

        Hi Dumbold -exactly because you and many think the problem is with conservatives, you should avoid using the same word in any other sense.

        As for the warrior analogy IIRC the concern is that too stark a warning may inspire depression and apathy, as in the small group who think it’s already too late for anything so no need to protect nature.

        • jpcowdrey Says:

          Perhaps we should be using the word ‘reactionary’ instead of ‘conservative’ in the political sense, since that is a more accurate descriptor.

          Hope that doesn’t confuse you, maurizio. You’re so easily confused.

          • omnologos Says:

            Most people only read titles. I wonder how many will get one meaning and how many another one

          • dumboldguy Says:

            Unlike you , most people are able to deal with the fact that many words have more than one meaning (and also understand that there are such things as context and nuance).

          • omnologos Says:

            Yeah right. I suggested to use a synonym and you understood I asked to drop the use of a word. So much for being able to deal with facts and meaning.

        • dumboldguy Says:

          I knew it! I should NOT have encouraged Omno. Now he has gone off the deep end and suggested that we drop a very important word from the language, and given us perhaps the least important reason why “stark” warnings about AGW should not be given.

          Good old Omno! When it comes to thinking, we can count on him getting here firstest with the leastest!

          • omnologos Says:

            I am sure in a Back to the future remake you’d be a convincing old Biff. Pity the cause that’s got you mindless bullying on its side.

          • dumboldguy Says:

            Actually, YOU would be the more convincing Biff because you share his handicaps related to the use of the language, if you can recall how “inexpressive” and confused Biff was. Like you, much of what he said just didn’t “come out right”. They would also have to “hulk” you up a bit in the makeup department because you don’t look the part.

            I do apologize that you have felt victimized by what you call my “bullying” to the point that you have to whine in public about it, and would suggest that real men don’t get mad and whine, they simply get even. You know where to find me should you ever find the brains and guts to do so.

            (PS To help you with your language deficit, may I also suggest that “mindless” is the wrong adjective to use when describing my “bullying”? Just because nearly all of it goes over your head doesn’t mean it’s mindless).


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