scenario.txt ------------ p1k3.com/2013/5/6/scenario.txt Dave posed a question earlier tonight: What's actually the worst case scenario for climate change? I gave what I think was probably too simpleminded an answer: The worst case scenario is systemic collapse within a couple of centuries, mass die-offs, the human species extinct or reduced to stone-age levels of tech and population. There was some argument about this, especially after I said I give humans maybe a 50/50 shot of still existing in 200 years. People seem to view that as pretty pessimistic, which of course it is. So thinking about it, neither idea ("climate change might wipe us out" and "we might get wiped out soon") is exactly the stuff of informed professional analysis. It's the half-baked opinion of some guy who has read a handful of books and spent a bunch of time on the internet. My friends know I'm given to sweeping statements and hyperbole. (By definition, they've been able to stomach remaining my friends through all the sweeping statements. It's a rare sort of fortitude and I value it greatly.) I'm not a person who knows what the worst case scenario for climate change is. I may not even be a person who's qualified to figure out who DOES know that. But that's not to say that these opinions don't constitute a form of knowledge. Here's sort of a working model of the historical moment: [best case | way unlikely] . Nothing happens. The denialist / skeptic end of the spectrum is right, despite acting like a pack of assholes. Ditto anti-environmentalism, my uncle who keeps pointing out that petroleum is biodegradable, and Republicans generally. . . There's some bad stuff happening but we fix it. . . Shit gets pretty ugly for a long time. [pretty likely] . . . . . . . All die. Oh, the embarrassment! . [worst case | unlikely-ish] This probably isn't what a climatologist or a wildlife biologist or even a serious, widely-read layperson with crossdisciplinary interests and background in the sciences would tell you. Not that it wouldn't match factual claims, but that it's not even the same KIND of thing those people would tell you. It's a sketchy map of a territory half-glimpsed through fog. What occurred to me is just how many of my working assumptions and schemas are no more rigorous than this. Within a handful of very narrow domains, I'm an expert. Outside of those domains, nearly everything in my understanding is of this kind. In itself, that's a useful realization to have. Because it's not that this knowledge is useless. On the contrary, it's probably the only thing that permits me to function. The trick isn't that credible people won't form opinions of this kind; it's that they will usually know (or at least be capable of discovering under reflection) the continuum of their certainty. You have to _start_ with some kind of model or you'll never arrive at one you can use for anything. And yet you have to hold most of your models lightly, understand them as provisional, revise them without mercy, replace them willingly, subject them to the scrutiny of the things you know well - or you're doomed to something between trivial absurdity and devastating ignorance. -- bpb