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climate change speed
Climate change is one of those (many) phrases that every reader/listener interprets in their own way. James Annan has interpretted it in one way in a discussion which I'll summarise as "the a priori1 position that climate change would be detrimental has no scientific/logical underpinning". (Well, actually I think he's really expressing the converse: "that no change is the best possible outcome, is not necessarily wrong"; but it amounts to the same thing.)
Put in yet another way: Given that it's unlikely that some cosmic conspiracy has put us a maximum of some sort of climate-ecosystem-human-society efficiency, it's hard to argue a priori that change would be a bad thing, as it might take us somewhere better. (The metric of exactly what is better is irrelevant to the argument, but I was disappointed that James' arguments were all pretty western hemisphere-acious.)
However, I think there's a fatal flaw in this argument. I think one can argue a priori that the speed of climate change could be detrimental, even if the place one ended up was some how "better" (always assuming we reached an equilibrium before economic/ecosystem meltdown). It seems quite clear that neither existing human societies, nor natural ecosystems (if such still exist) can respond to a rapidly changing environment without detrimental impact.
So, my point is that climate change is a problem both in terms of magnitude and rate of change. Some of us are as much worried about the speed of change as we are of the eventual magnitude. (James does allude to the issue of rapid climate change in passing, but I think misses it's importance in discussing whether the status quo may or may not be better than the result of climate change).
Given that the speed of change is at least as important (if not more so at some point) than the magnitude of the change, then arguments about our ability to adapt being relevant need to be taken with a grain of salt. The first question should not be whether we (or our ecosystems) can adapt enough, but whether they can adapt as quickly as things are going to be changing.
I think we now know that the speed of change is going to be a problem, but I would argue that actually the most likely a priori position would have been to expect just that: Anthropogenic climate change is most likely to be detrimental - if only because of the speed! And unlike James, I do think this is a logical position!
Two degrees of Warming (from "Bryan's Blog" on Friday 09 January, 2009)