Sunday, December 19, 2010

Climate notes from all over

Yes, it's cold in England and much of Europe, and climate change skeptics are poking fun at those who in the last decade predicted the virtual end of winter snow for those countries currently under a lot of it.

Yet, Real Climate has a post about the ways that it may indeed be all related to AGW, and in particular to do with sea ice over Canada way. But it's all very complicated and no one knows for sure.

Now, 2010 is bound to be high on global average temperatures, but it does seem a year most notable for sudden extremes in all aspects of weather - the Russian heatwave, the Pakistan floods, the one in a 1000 year flood of Tennessee. And now England and Europe being unusually cold.

Given the slow but (on the longer scale) steady progress of global temperatures (Tamino has an excellent post showing how all the temperature data sets collected and calculated in different ways are still all following the same path,) it will be interesting to see whether the public over the next year or two becomes convinced of global warming not so much due to high local temperatures, but more because of erratic weather swings.

Meanwhile, Judith Curry's blog continues to be a big puzzle. As someone commented somewhere, it's like she decided to rebuild climate science from the ground up. On the positive side, she doesn't dispute the very, very basics of CO2 as a greenhouse gas, but when she gets into anything else, it's actually very hard to tell where she is going. (In fact, some posts, talking about science generally, give the impression she is seeking to rebuild science itself from the ground up.) She seems to find many things "interesting" and worthy of her looking into further, but at this rate is seems she will come to some conclusion by about 2020.

None of her mainstream climate critics have said much about her lately, a bit to my surprise, but Judith went to the AGU meeting last week in San Francisco, and her post showing her slides ends with these two:

Slide 14

In conclusion: The drive to reduce scientific uncertainty in support of precautionary and optimal decision making strategies regarding CO2 mitigation has arguably resulted in:

  • unwarranted high confidence in assessments of climate change attribution, sensitivity and projections
  • relative neglect of defining and understanding the plausible and possible worst case scenarios
  • relative neglect of decadal and longer scale modes of natural climate variability
  • and conflicting “certainties” that result in policy inaction

Slide 15

A way forward is the decision analytic framework of robust decision making under deep uncertainty, which emphasizes scenario discovery and uncertainty analysis and identifying a broad range of robust decision strategies.

Implications of such a strategy for climate research are an increased emphasis on:

  • exploring and understanding the full range of uncertainty
  • scenario discovery using a broader range of approaches
  • natural climate variability, abrupt climate change, and regional climate variability
Clear? No, it wasn't to me either.

But - I am happy to see that James Annan, who was strongly critical of Curry's "Italian flag" post several weeks ago (I don't think she has finished talking about them yet) saw her AGU talk, and has this to say about it:
He also emphasised the importance of only speaking in areas where you had earnt credibility based on your published record, which formed an interesting backdrop to Judith Curry's talk later that day. She devoted her time to accusing the IPCC of ignoring the tails of the pdfs of climate sensitivity that were clearly presented in the very figure that she repeatedly referred to and explicitly emphasised in the summary ("values substantially higher than 4.5C cannot be excluded"), then read out a few cartoons and finally, literally out of nowhere, concluded that therefore they had underestimated the magnitude of decadal variability and that their detection and attribution results were unsound! Really, I'm not making this up, it was actually how it happened. These latter topics were first introduced on her concluding slide and there was no hint of supporting argument. She also talked about the "modal falsification" of Betz 2009, (which I haven't read but just googled now, is there a free version somewhere?) so I asked if and how this "falsification" (and she used the scare quotes herself) was distinct from assigning a low posterior probability in a Bayesian sense. She replied that it could be considered the same, at which point some of the audience were shaking their heads and others were nodding in agreement. From which I conclude that nobody, including Judith, knows what Judith means. Unfortunately, she didn't seem to be anywhere to be found at the end of the session and I didn't see her at any of the other relevant sessions where people actually dealing with these sorts of issues were actually presenting concrete results.
So, I am not alone in not being able to make head nor tail of Curry, and my lack of science qualifications are not the reason why. Romm's description of her as a "confusionist" seems as apt as ever.

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