Climate Feedback

Climate consensus: is opinion even relevant?

For anyone interested in the consensus on climate change, there’s a very interesting feature by Joseph Romm who blogs over on Climate Progress on Salon today, in which he argues that opinion on the cause of global warming is irrelevant. What is relevant, says Romm, is the overwhelming body of well-tested science and real-word observations.

Romm makes the case that the perpetual use of the word ‘consensus’ by the media, scientific community, and others mistakenly frames climate change as an issue of opinion, rather than one of scientific scrutiny based on data and evidence:

“Science doesn’t work by consensus of opinion. Science is in many respects the exact opposite of decision by consensus…One of the most serious results of the overuse of the term “consensus” in the public discussion of global warming is that it creates a simple strategy for doubters to confuse the public, the press and politicians: Simply come up with as long a list as you can of scientists who dispute the theory. After all, such disagreement is prima facie proof that no consensus of opinion exists.

So we end up with the absurd but pointless spectacle of the leading denier in the U.S. Senate, James Inhofe, R-Okla., who recently put out a list of more than 400 names of supposedly “prominent scientists” who supposedly “recently voiced significant objections to major aspects of the so-called ‘consensus’ on man-made global warming.”

Opinion polls on the climate consensus crop up from time to time. Coincidentally one such poll came to my attention this week, via email, and is being discussed over on Roger Pielke Sr’s blog.

The posts basically describe the rejection, first by the AGU journal EOS and secondly by Nature Precedings, of a research poll by Pielke Sr, James Annan and Fergus Brown surveying whether there is agreement among climate scientists on the IPCC fourth assessment report.

Pielke Sr. writes:

“It is clear that the AGU EOS and Nature Precedings Editors are using their positions to suppress evidence that there is more diversity of views on climate, and the human role in altering climate, than is represented in the narrowly focused 2007 IPCC report”.

There’s a further post and comment stream over on Brown’s blog.

I’m not privy to the inside information on why their paper was rejected from both EOS and Nature Precedings, but it seems to me that there are (at least) two point to be made here:

Firstly, as William Connolley points out in the comment thread on Brown’s blog, the conclusion of the poll that “there is not a universal agreement among climate scientists about climate science as represented in the IPCC’s WG1” is a strawman.

This is precisely one of the bugbears that Romm has with the term ‘consensus’: is it ‘unanimity’ or ‘the judgment arrived at by most of those concerned’?

“Many, if not most, people hear the second meaning: ‘consensus’ as majority opinion”, argues Romm – meaning that even if every living scientist doesn’t agree, there can still be a consensus.

As for sample design, the authors themselves admit that the sampling does not follow standard protocol for opinion polls and further “cannot be tested for statistical significance” as “there is no currently available information on the complete community of ‘climate scientists’”.

This whole discussion is reminiscent of that on the survey by Hans Von Storch and Dennis Bray last year, discussed here on Climate Feedback, which similarly attempted to survey climate scientists’ responses to bold statements on climate change, and had potentially biased sampling.

Whether or not opinion on climate change is relevant, it seems the debate is still open on how it can be gauged in a way that is scientifically credible.

Olive Heffernan


  1. Report this comment

    Bishop Hill said:

    Chambers Dictionary defines consensus as: “agreement of various parts; agreement in opinion; unanimity.”

    So to suggest that the meaning inferred previously was “majority opinion” is clearly rubbish.

    “Consensus” has been used almost constantly as a way to shut down dissenting opinions by inferring near unanimity.

    “We must ratify Kyoto because the majority of scientists think global warming is a fact” just doesn’t have the same impact as a “consensus” does it?

    The problem with attempting to redefine words to suit your arguments is that readers then have to wonder what other words you have redefined, and whether anything you say can actually be trusted.

    And by the way, add Joanne Simpson to the list of sceptics.

    PS When are you going to link to Climate Audit? Or are dissenting opinions forbidden here?

  2. Report this comment

    Steve Bloom said:

    Th abstract says in part that there are "a significant number of climate scientists who disagree with the IPCC

    WG1 perspective."

    But then in the second paragraph we find (as noted in the post) the admission that “the poll cannot be tested for statistical significance.”

    (emphases added)

    IOW, this survey is self-cancelling within its own terms. I don’t see how anybody could be surprised that there was no interest in publishing it.

  3. Report this comment

    David B. Benson said:

    It does not matter.

    Here is what does:

    (1) Increasing CO2 causes increased global warming and ocean acidification;

    (2) Burning fossil fuel causes increased CO2.

  4. Report this comment

    pauld said:

    In addition to the issues you raise, another major problem with talking about a consensus is that no one clearly defines the issues on which the consensus exists. Very few people dispute that the earth is warming, and that CO2 gas is a greenhouse gas that will tend to warm the earth, other things being equal. If this is the consensus, then sure it exists and is confirmed by observations. Most people, however, want to claim that a consensus exists that involves more. Few people define what that that more is? For example, Al Gore refers to the “consensus”, but includes in his movie speculations that go far beyond the IPCC report. His slides on the long-term relationship between CO2 and temperature is poorly explained and as presented does not represent current scientific thought.

    In any event, there are many aspects of the climate debate and few people try to define the issues on which a genuine consensus exists.

  5. Report this comment

    bigcitylib said:

    I don’t the results of the survey are necessarily to be faulted, but Pielke’s interpretation is like a “torqued headline”.

    1) There are no pure deniers turned up by the survey, which is surprising given the claim of “no consensus”.

    2) About 50 per cent of those surveyed go with the IPCC consensus.

    3) About 70/80 percent of those surveyed go with the consensus or WORSE.

    I wrote more about this here:

  6. Report this comment

    JamesG said:

    Can anyone who uses the term denier please tell us all what facts are being denied. I don’t think I’ve seen anyone say there hasn’t been a net warming. Neither have I seen anyone say that increased CO2 – all things being equal – wouldn’t warm the planet. The argument has always been about the extent of warming in the future ie the correctness of models, and about the effects of the warming. Since the model predictions / projections, are very uncertain even according to the modelers and the IPCC and since any potential consequences weather-wise are very speculative and are often quite wrong (eg gulf-stream shift, hurricanes), again please tell us what facts are actually being denied.

    We’ve all seen overt propaganda from both sides and the IPCC scientists are just as guilty of using “a simple strategy…to confuse the public, the press and politicians:”, by predicting disasters with a certainty far beyond what they care to write in their actual papers or indeed what the IPCC actually agreed upon. Opinions are indeed being presented as facts. The onus shouldn’t be on the public to find the truth amongst the spin.

    I am certain though that at least there is a consensus, by any definition, on the need for alternative fuels and the need for pollution controls, which means that “opinion on the cause of global warming is irrelevant” is entirely correct but it is also correct that whether the science of global warming is correct or not is probably not too important either. I wish people would focus on common areas of agreement rather than on arguing pointless differences all the time.

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    Patrick Henry said:

    Only one opinion is important.

    The one which keeps money coming in to the climate modeler’s coffers.

  8. Report this comment

    Dodo said:

    Bloom: “I don’t see how anybody could be surprised that there was no interest in publishing it.”

    Do you see any reason to be surprised at the interest this unpublished study has caused on so many climate blogs?

    Bigcitylib: "There are no pure deniers turned up by the survey, which is surprising given the claim of “no consensus”."

    The sample consisted of scientists. Why would anybody with scientific training deny the fact of radiative warming from increasing GHGs? FYI, the debate has moved on to discussing the magnitude and seriousness of this warming long time ago.

  9. Report this comment

    Mark Bahner said:

    “It does not matter.

    Here is what does:

    (1) Increasing CO2 causes increased global warming and ocean acidification;

    (2) Burning fossil fuel causes increased CO2."

    No, what matters is how much warming is expected in the 21st century?

    The IPCC has never answered that question. None of the IPCC assessments have ever included scientifically valid predictions of warming in the 21st century.

  10. Report this comment

    Alan said:

    So, because symantics is the best argument the willfully ignorant can now muster, journals should start publishing non-sequiturs?

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