I expect these points to change with the evidence, but here is where I am right now...
1. It is by now pointless to deny that global warming is man-made to a considerable degree.
2. It is a very real problem. If you don’t believe me, go visit the deltas of East Bengal or Bangladesh and think about it again. Sweden I am not worried about and Greenland may become valuable, but where do we put the losers and no this isn’t just a few small islands in the Pacific.
3. I can imagine Manhattan and other major cities taking protective action against rising water levels, much as the Dutch do today. I recall reading that the Dutch spend about as a high a percentage of their gdp defending themselves from water as the U.S. does on national defense. That is quite a burden, but it is better than forsaking economic growth.
4. Like Arnold Kling, I do not much trust climate models. Perhaps I have spent too much time doing macro, and the experience carries over. Nonetheless uncertainty about final effects gives us more to worry about, not less. It is the worst-case scenarios for global warming which worry me, not the middling scenarios. Variance is our enemy in this matter.
5. I don’t have a good plan for what to do. Imagine passing and extending Kyoto and turning 2/3 of the U.S. energy supply into nuclear, wind, and solar power. Heroic achievements, to be sure. But if China and India continue to industrialize, global warming will likely continue and perhaps accelerate, as I understand current knowledge.
6. I have yet to see a real plan which recognizes three points: a) without continued economic growth the world will probably fall apart, b) the problem is real and significant, c) any good preventive solution would require an enormous amount of concerted action across both time and across nations.
7. How much does the framing of the problem contribute to our political views on the matter? How much would we spend, or how intensively would we organize global action, if a typhoon were headed right for Bangladesh? An earthquake? A war? A much slower set of changes, not fully our fault? An out-of-control American nuclear weapon? Should it matter?
8. If we could relocate all the losers-to-be into freer and richer countries, should we consider this a satisfactory solution? Or are we still massive and unjustified aggressors if they are crying to us: "Don’t let it happen, don’t let it happen!"?