Back to Schmittner

RealClimate: Ice age constraints on climate sensitivity

Real Climate has a long and fairly technical look at the Schmittner paper, and also concludes that there is reason to think its estimate of climate sensitivity, although within the ballpark of current "best estimate" anyway, may be on the low side.

But the bit I wanted to note here was about the poor reporting of the paper, which I think occurred just about everywhere. Even The Economist called its report "Good News at Last?", which is kind of a meaningless statement unless you are prepared to address the question "compared to what?"

Anyway, as Real Climate points out, part of the problem was really with the press release itself, and some fairly careless comments by some of the authors, who surely have to be more cautious about "sceptics" taking quotes out of context:

Unfortunately, the media coverage has not been very good. Partly, this is related to some ambiguous statements by the authors, and partly because media discussions of climate sensitivity have a history of being poorly done. The dominant frame was set by the press release which made a point of suggesting that this result made “extreme predictions” unlikely. This is fair enough, but had already been clear from the previous work discussed above. This was transformed into “Climate sensitivity was ‘overestimated’” by the BBC (not really a valid statement about the state of the science), compounded by the quote that Andreas Schmittner gave that “this implies that the effect of CO2 on climate is less than previously thought”. Who had previously thought what was left to the readers’ imagination. Indeed, the latter quote also prompted the predictably loony IBD editorial board to declare that this result proves that climate science is a fraud (though this is not Schmittner’s fault – they conclude the same thing every other Tuesday).

The Schmittner et al. analysis marks the insensitive end of the spectrum of climate sensitivity estimates based on LGM data, in large measure because it used a data set and a weighting that may well be biased toward insufficient cooling. Unfortunately, in reporting new scientific studies a common fallacy is to implicitly assume a new study is automatically “better” than previous work and supersedes this. In this case one can’t blame the media, since the authors’ press release cites Schmittner saying that “the effect of CO2 on climate is less than previously thought”. It would have been more appropriate to say something like “our estimate of the effect is less than many previous estimates”.

Well, it's hard to see how that last suggestion would have made that much difference, but still, it seems to me the authors could have been more careful.