Krugman's long article is worth the time, and I urge you to read it. The Master's is on TV today and provides a perfect backdrop for this important article. Krugman's other significant "scenario" is a less well understood situation in western Atlantic. The possibility of the Gulf Stream dissipating has been talked about for a long time. We just do not know what the increase in sea water temperatures at the surface off the Bahamas and the Antilles will do to the Stream. There is a possibility that it will strengthen the Stream and contribute to warmer temps across the northern Atlantic and on into western Europe and over the top of Scandinavia. The further north such a warming went the faster the process of releasing methane from permafrost would be, accelerating global warming and increasing chaos in relatively contemporary climates and ecosystems. Of course, if the Stream dissipates, then the UK and northwest Europe will become increasingly untenable.
So, the problem that Krugman discusses is how to galvanize politics and "special interests" into a coherent and maximally effective "social" plan to combat our own climate-changing effluents. Krugman says he is most in favor of a "big bang" approach, but I am not sure he has convinced me that that is the best way, or the most plausible politically. On the other hand, I am quite certain that the idea of loving future generations will be a non-starter, that we are about as hyped on the concept of global warming as we will ever be ... short of really chaotic and destructive weather focusing our attention on climate change.
In my generation the problem is almost completely a non-starter. In suburban Tucson new SUVs are a plague, though happily driven by aging citizens whose sense of impending senescence leads them to believe they are safer in these behemoths. Human nature is to take short term actions that protect the self and family over long term actions that protect the neighbors. Human beings of all ages live by the illusion of survival by the "skin of our teeth."
You have seen the House of Representatives pass a "cap and trade" bill that will not go through the Senate. It will not pass the 60 vote test because the GOP is playing a different game, a game of "chicken" founded on the belief that the mid-term elections this fall will significantly reduce the Democratic majorities, perhaps even deliver the Senate into GOP hands. The Tea-Party folks who feel slighted by the Bush-Obama policy to direct recovery efforts down from Wall Street will vote mindlessly for candidates whose understanding of global warming is sketchy at best and predominately disbelieving. As a prediction, then, I feel confident that almost nothing serious will be done by Congress for the next ten years. Of course the green will fade to yellow during this time and our descendants will have a hell of a time recovering from our self-centered behavior.