Tuesday morning has at least 4 sessions I could have been interested in. Leave EPICA for later and start off (cos I happen to pass the room) with Latif on MOC; which to me provides more evidence not to worry about it. Thence into the climate sensitivity session, which is packed.
Matt Collins talks about the Hadley work on perturbed-physics models for climate sensitivity, and shows that by and large QUMP spans the parameter space of the AR4 models. So we only need HadCM3 :-) (note: some of this stuff is my interpolation into peoples talks, so you’ll have to be careful what you read). Knutti tries to use the seasonal cycle to constrain climate sensitivity. I *thought* this was going to be about throwing away those CP.net models that have an unreasonable cycle, and discovering that the long tail of high sensitivity goes away. It wasn’t, quite, though it may have been roughly equivalent. The seasonal cycle is some measure of how the model responds to changes in forcing; and using this in combination with the obs, I think K was scaling the CP.net results somewhat; and this definitely reduced the long tail, though the details escape me. Kriegler was trying to use the expert-estimation method for trying to say interesting things about probabilities of climate change and tipping points; but probably the most interesting bit was an expert comment “tipping points are likely to exist but little of substance can be said about them”.
Lastly Dave Frame, on more theoretical stuff. Some clashes with the JA/JH work; and much of it over my head; but there seem to be interesting theoretical problems with deciding in some sensible way what your Bayesian priors should be. But you want James Empty Blog for that.
Coffee; brief hello to sci.env’s Raymond Arritt, who is chairing the next session; stop in it for the first few talks, esp Richard Jones who looks very suave.
Lunch with Gavin and josh him about his NYT piece :-). The Pielkes only had nature :-)) His apple seems to cope better with the wild DNS swings of the EGU network than my windoze, as we both look over his NYT piece and giggle at some blog comment(er)s. Mentioning no names.
Currently in EGU Hans Oeschger Medal Lecture by Bernhard Stauffer about ice cores, the long forgotten history. When CO2 was first measured in ice cores they got quite implausible values – up to 1000 ppmv. Which turns out to be due to a variety of problems, mostly lab contamination (but every now and then the septics discover the old contaminated measurements and say, aha!). Notes (sort-of as Ruddiman did, but interprets differently) that there is20 ppmv variation in CO2 over the Holocene. Must plot this out on a scale where I can see it sometime; you can’t see it on the usual pics).