New CBO paper on climate change

It is here and a short summary is here.  It is a good overview, noting that it does not cover the parts of the world most likely to be severely hit.  The paper is especially good at discussing the policy implications of scientific uncertainty.  This passage outlines a key issue and, in bureaucratese, asks how much it is possible to do:

Those insights have spurred some researchers who are particularly worried about low-probability but high impact outcomes to call for limiting long-term warming to no more than 3°F to 5°F with a high degree of certainty. However, since about 1.4°F of warming has already occurred, and past emissions have made a substantial amount of further warming inevitable, limiting long-term warming to such levels with a substantial degree of certainty would probably require very dramatic and potentially very expensive curtailment of expected future emissions. There is a large difference in costs between a policy that leaves a 50 percent risk of warming exceeding 5°F and a policy that virtually eliminates that risk. In moving along the continuum of risk from the former to the latter, each increment of risk reduction is likely to come at an increasing price.

I was taken by Paul Collier's earlier discussion of the ethics of climate change.  Using different terminology, given that "probabilistic aggression" against people in the poorer countries is problematic, concern for climate change is (or rather should be) the libertarian point of view.

I also found useful the dialogue "The Big Heat" in the June issue of Discover magazine (not yet on-line).  It's the best discussion I've seen of why the climate change skeptics clutch at a few pieces of (supposedly) favorable evidence but don't think about the issue at the very deep level or require that their scientific theories cohere as a whole or predict a wide range of climate-related data.

That all said, I come to the Waxman-Markey climate change bill.  Here is one estimate that the impact of that bill on global temperature will be very small.  I am not at all endorsing that estimate, but as someone concerned with the issue as a whole, I would like to know: what is the highest quasi-credible estimate for how much good that bill will do?

I would like to know.


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