I’ve been travelling and so haven’t really had much chance to keep up with what’s going on. I have, however, finally managed to watch the Congressional Hearing on Climate Science: Assumptions, Policy Implications and the Scientific Method. It was all rather predictable and this Washington Post article pretty much nailed it in advance.
Judith Curry played the uncertainty card and then suggested that the inability to definitively attribute periods of warming in the past, suggested that we can’t make strong attribution claims about recent warming periods. Well, this is silly, since we clearly have much more information about the recent past than we do about the distant past. The whole attribution issue has also been covered extensively, both here and on Realclimate. Ideally, Judith should recognise that just because she is uncertain about this, does not mean that everyone is uncertain.
John Christy played the lack of a hotspot card and also promoted his model-observation comparison, that he claims illustrates that the models have failed. There is an interesting Climate Dialogue discussion about the tropical hotspot, in particular the contribution by Steven Sherwood. I was pleased that, during the hearing, Michael Mann pointed out that if the troposphere has indeed warmed less than we expected, that that would imply that our climate is more sensitive than we expect, not less, since the tropical hotspot is indicative of a negative feedback. John Christy’s model-observation comparison is also discussed in this Realclimate post and it’s clear that there are a number of issues to consider, such as how you baseline the datasets, the model spread, and the structural uncertainty in the observations. It seems clear that the discrepancy between the models and the observations is nowhere near as large as his comparison suggests.
Roger Pielke Jr’s presentation was more interesting, in that I found some of what he said quite reasonable. He brought up a carbon tax, mentioned that we were unlikely to be able to substantially reduce our uncertainty prior to needing to make policy decisions, and even mentioned that, in many cases, we would not necessarily expect a trend in extreme events to have emerged, even if we would expect it to emerge were we to continue emitting CO2 into the atmosphere. On the other hand, he stills seems to blur the distinction between not detecting a trend, and there being no trend. He seems to ignore that, in many cases, we’re interested in whether or not there is an increase in the intensity and frequency of the most extreme events, rather than simply an increase in these events overall. He seems to fail to properly distinguish between detection and attribution, and he often focuses on damage/cost without making it all that clear that a lack of a trend in these does not necessarily imply anything about physical climatology.
I think this is a bit unfortunate, because these are important and interesting issues, and it would be good if he could be more careful in how he presents his information. It should be possible to do so in a way that is consistent with the evidence, allows for more meaningful discussion, and makes it harder for others to criticise what he says (which he appears to particularly dislike). On the other hand, one can’t discount that this is a feature, rather than a bug.
You’ll notice that there are two things I haven’t really mentioned. One is Mike Mann’s testimony, which was pretty much mainstream science (or, more correctly, science), and the other is how the hearing focussed somewhat on various conflicts in the public climate debate. Well, the latter just seems rather irrelevant to me, even though I do think that we should avoid attacking those who present alternative views; I’m all for an improved public dialogue about this topic, even if I don’t think it is actually possible. On the other hand, I see nothing wrong with publicly criticising what others choose to say. Even though I’m all for better dialogue, I’m certainly not in favour of not criticising what others say when it’s clear that what they’re presenting is not consistent with the best evidence available today. My rather cynical impression is that the complaints about tone is motivated more by a desire to reduce criticism of what is said, than a desire to actually improve the public dialogue.
A post by Stoat, to whom I forgot to link 😉 .