Michael Tobis wrote: > Opitmizing is what James does, and as a possibly incurable dabbler I > have done some of it too. I think he is more asking for precision of > language than arguing that large and rapid changes are likely to make > us better off. >
That's just about right, although I would like to emphasise that this is not just some quibble about the precision of language. I see terms like "optimal climate" or "optimally adapted" as playing the role of though-stopping appeals to some authority of logic or analysis, which in reality does not exist (even if it is not be the deliberate intention of the authors to pull this trick). Even if one is prepared to frame the problem as purely one of maximising utility, then there is still a whole lot of work (and many assumptions and estimates) required to reach any conclusions at all. Most of the credible (IMO) analysis comes down on the side of taking modest but significant action now, but it's nowhere near as trivial as simply saying something along the lines of "change is bad, so we should try to stop it". Parables about water mills running dry trivialise the debate. There are lots of non-functioning water mills in the UK, but that's not because the rivers have moved! > On the other hand the flavor of the argument remains convincing to me. > The likelihood that any substantial change in climate will be > beneficial in the net is quite small, because the adaptations we have > set up are local and costly. It's a matter of rate of change, as well as magnitude. It may be that aiming for no more than 0.1C/decade (say) of forced response is a more meaningful target than any specific equilibrium CO2 level. > My expectation that interannual oscillatory behavior in response to > strong forcing will increase is sufficiently strong and the evidence > of such behavior in GCMs sufficiently weak that it causes me to > suspect that GCMs have a sort of near-equilibrium bias. That is, I > suspect GCMs filter out forced transient variance on interannual to > decadal time scales. I have no sensible ideas as to how to investigate > this hunch, and it would likely be a more expensive proposition than I > can muster anyway, but I'd welcome speculation by others on the topic. It's an interesting idea, and it certainly seems plausible that some/many GCMs underestimate natural variability in various ways. One main goal of this workshop was to think of ways to compare observed and modelled variability, but the data are really pretty poor once one goes back beyond a century or so. http://www.astr.ucl.ac.be/index.php?page=Wokshop_assim James --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups Global Change ("globalchange") newsgroup. Global Change is a public, moderated venue for discussion of science, technology, economics and policy dimensions of global environmental change. Posts will be admitted to the list if and only if any moderator finds the submission to be constructive and/or interesting, on topic, and not gratuitously rude. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/globalchange -~----------~----~----~----~------~----~------~--~---
