When it's right to be reticent
The caution of climate scientists is commendable even if caution is out of fashion, says Philip Ball.
Jim Hansen is no stranger to controversy. Ever since the 1980s he has been much more outspoken about the existence and perils of human-induced climate change than most of his scientific colleagues. A climate modeller at NASA's Goddard Institute for Space Studies in New York, Hansen has flawless credentials to speak about climate change, and has fought for his right to do so.
Comments
Good article, although I side with Hansen.
Reticence just plays into the hands of the not inconsiderable denial industry. It's already hard enough for the public to identify with the boffins - have a look at this account of a debate involving Gavin Schmidt vs Michael Crichton...
When we can provide scientists with a number of similar Earths to experiment with, then we'll probably achieve a reasonable level of scientific certainty. Until then, I'd prefer to hear the scientists speak more candidly, even if they have to qualify it with the doffing of their scientific hats.
Posted by: oisin | March 30, 2007 03:22 AM
Having read both this, and Jim Hansen's 'Scientific Reticence'
preprint,I'd strongly urdge Phillip Ball to considering editing his piece to op-ed length and sending it where it could do the most good by sheer force of contrast- the Ed Page of the Wall Street Journal.
Unless he makes such a move , the General Theory Of Everything dictates that it will be reduced to parody by ellipsis as the Daily Telegraph and The Washington Times try to invert its good sense-- if and when it belatedly percolates to them through
the producers of The Great Global Warming Hoax, or the crew of Limbaughnauts orbiting PlanetImhofe.
The countdown to editorial catastrophe has begun.
Posted by: Russell Seitz | March 31, 2007 12:47 PM
The problem with translating science into public policy is that scientists aim for a "proof beyond a reasonable doubt:" a scientist would not fully commit to a theory if there are other plausible explainations for the observation.
Public policy, however, should not be made on the basis of such a high standard of proof, since in such matters it is not usually possible to avoid making a decision one way or the other. A lack of a decision to change current policies is a decision to continue with the previous policies.
Public policy should instead be made on some version of a "balance of probabilities." If several scientists conclude that one view has a 75% likelihood, while the opposite view has a 25% likelihood, policy should reflect the more likely option.
I would therefore suggest that scientists offer their estimates as to the likelihood of the correctness of their theories. Such estimates would not be used by their colleagues as in any way conclusive, but would be directed at policy-makers.
Posted by: Katya Permiakova | April 1, 2007 04:35 AM
The reticence that Hansen bemoans and Nature applauds may appropriate for science, but it is not for public policy. The problem is scientists are being asked to contribute to public policy discussions without changing their biases. It is one thing to ask whether something is scientifically true (i.e. essentially proven). It is another to ask what the possibilities are. The purpose of the IPCC report is meant to influence public policy, and therefore it should talk about possibilities, such as the "dynamical processes" that they refuse to enter into the public policy arena. This does us a disservice by essentially biasing the policy debate toward Business As Usual, without making this bias clear. For more than a decade, the debate over human greenhouse gas emissions and climate change has been analogous to the players of Russian Roulette debating how many chambers are loaded between trigger pulls. Of course the debate should be about why we are playing such a foolish game. In the face of uncertainty, the wise course of action is to consider possible outcomes, not to wait for the certainty about the path we are on. Would you step into quicksand because someone had not proven that its depth was greater than your height?
Posted by: Earl Killian | April 2, 2007 04:17 PM
I made no call for scientists to "speak out unscientifically...without caveats and caution". Examination of the Charney(1979) and Cicerone(2001) National Academy of Science reports reveals them to be full of appropriate caveats, authoritative and clear. They were of great value.
Posted by: James Hansen | April 2, 2007 06:49 PM
I see several problems with this article. Jim Hansen’s views about
man-made global warming in 1989 were based on science, not just sound
intuition, published in his 1988 paper in Journal of Geophysical
Research-Atmospheres, for example. The hearing that Congress held in
1988, when Hansen spoke about his views, is a great example of a
scientist speaking out without reticence, based on scientific results.
Some scientists do not feel they need to wait to collect 20 years of
data confirming a prediction from a model before they can stick their
heads out, especially when there is so much at stake. Hopefully there
will be more of those scientists soon because once the ice-sheets have
melted, even though scientists following Ball’s guidelines may finally
consider they can ‘afford’ to abandon their reticence, they may have a
hard time sticking their heads out above the rising sea waters.
Hansen, J., Fung, I., Lacis, A., Rind, D., Lebedeff, S., Ruedy, R.,
Russell, and G. Stone, P. Global climate changes as forecast by
Goddard Institute for Space Studies 3-Dimensional Model. Journal of
Geophysical Research-Atmospheres 93: 9341-9364.
Posted by: Ines Horovitz | April 3, 2007 02:58 PM
I’m interested that most of this feedback supports Jim Hansen’s proposal. I wonder whether some of that stems from the different public and political climate each side of the Atlantic. Speaking from a country where the political right and left are vying to be ‘greener than thou’ (even if the talk has yet to be translated into effective policy) and where the government’s chief scientific adviser has been unstinting in bringing climate change to the fore, perhaps it is harder for me to see why scientists should need to risk giving ammunition to the climate sceptics by moving beyond the sober rigour of the IPCC report.
I should say that I support and value the way Hansen has spoken out about climate change. That seems a valid and important thing to do. What I don’t really see is why he feels the scientific community, as represented in this case largely by the IPCC, could and should do more than it does. I may have done Hansen a disservice in implying that caution and caveats should go out of the window (I did not mean to suggest that), but so long as the proper qualifiers remain, I’m not sure how his proposal could differ significantly from what the IPCC already says. To my mind, the message of the IPCC has always been pretty clear: global warming seems to be happening, is probably mostly anthropogenic, and poses a serious threat. This message has been conveyed clearly and forcefully by the reputable media (which admittedly is not necessarily the most vocal or influential sector of the media as a whole). I don’t think that the resistance to this message has tended to play up any hesitance in the IPCC reports, but rather, it has looked around with increasing desperation for voices that contradict them. Thus, when it bothers with the science at all, it draws on the likes of Lindzen, Baliunas and now Svensmark (none of whom should necessarily be judged by the company they have found themselves keeping), and portrays the IPCC as a disturbing conspiracy of enforced consensus. The resistance to IPCC in the US administration seems nakedly to be about a culture of denial coupled to a refusal to offend industrial interests; that in the automobile and petroleum industries themselves is motivated by blatant self-interest. I don’t believe that the confusion and disinformation spread by such parties would have been any lessened by a more outspoken stance on the part of the scientists – indeed, it seems likely that they’d just have been portrayed even more as bending the facts to suit their own non-scientific agenda. As it is, I feel that the restraint of the scientific community has given them now an unimpeachable authority in putting forth their more definitive and increasingly alarming conclusions.
I wonder, then, whether Hansen might be at risk of perpetuating the ‘deficit’ model of public understanding of science, by suggesting that if only we scientists spoke more loudly and clearly, people would agree with us. Sadly perhaps, it doesn’t seem to work that way. I suspect that most people who reject the notion of anthropogenic climate change do so not because they haven’t heard what the scientists think, but because they are not willing, for whatever reason, to hear it. That seems to me to be the real problem we face.
I don’t dispute that there was solid science behind Jim Hansen’s 1989 statements on human-induced climate change. But I’m not convinced that the science convincingly supported that conclusion at that point. Most climate scientists were not yet ready at that time to conclude the same thing with confidence (take a look at Richard Kerr’s Science article cited in my piece). I recall the long and careful process of searching for an anthropogenic fingerprint in the climate records during the early 1990s – that seems to have been an important part of the argument. I don’t mean to suggest that Jim Hansen was making his claims on the basis of flimsy evidence, less still that he was doing it in anything but good faith. But I do think there were sound scientific reasons many of his colleagues were not at that point ready to go so far.
I agree that public policy should not wait for scientific certainty (goodness knows what would happen to economic policy if we did that). This isn’t the issue. Scientists have been saying for a long time now that anthropogenic climate change is predicted, probably happening already, and bad news if it is. A public policy that resists taking action because this warning is not expressed at the 99% confidence level is one that is looking for excuses, not one governed by prudence.
Posted by: Philip Ball | April 8, 2007 11:01 PM
Surely melting ice caps would make water levels fall?
Also if CO2, water and heat are produced by burning fossil fuels why does everybody blame CO2 for rising temperatures and water levels? If plants fix energy from outside the ecosphere daily, surely there is only one way the climate can go if we continue to realise that energy?
Posted by: Keith Hart | April 11, 2007 09:56 AM
Is the discussion restricted to only scientific realms?
Posted by: Priyanka Sureka | April 12, 2007 09:23 AM