Manzi replies to Ezra Klein:
When thinking about time after 2100, we have, in cartoon terms, two choices: (i) simply treat it as unknowable fog, or (ii) attempt to guess. I think that if we take the first choice, then we simply try to forecast through the next century, and let future generations worry about the world beyond 2100 (though I’ll point out that it is a very unusual political debate in which we call trying to manage the entire world for about the next 100 years as “short-termism”).
If we take the second approach, how far out do we try to guess? The Nordhaus economic calculations that I cited in my post as formal attempts to compare odds-adjusted costs versus benefits actually extend out for 250 years. That is, they consider expected costs and benefits to about 2250. Therefore, Klein’s point is really about potential damages beyond 2250,not 2100. That’s a long way off.
This doesn’t mean that I don’t care about problems that might occur hundreds of years from now, just that I don’t care much about current predictions about those problems.