From Eugene Robinson no less:

That’s a lot of numbers, a lot of assumptions, a lot of scenarios. But even if the Copenhagen summit is wildly successful, the concentration of heat-trapping carbon in the atmosphere will continue to rise. This doesn’t mean the whole exercise is futile, it just means that Copenhagen won’t provide any definitive solution to what so many scientists say is an urgent problem.
It’s also true that even if all greenhouse emissions could magically be halted tomorrow, the elevated levels of carbon dioxide in the atmosphere — higher than at any time in the past 800,000 years, according to researchers who study Antarctic ice-core samples — would take many decades to decline to historical levels.
If the planet is warm now because of human-generated greenhouse gases, it’s going to get warmer. If the low-lying Maldives disappear beneath the Indian Ocean because the sea level rises, that will be a disaster. If “extreme” weather events such as major hurricanes do become more frequent, that will increase the potential for catastrophe in coastal cities around the world.
But if there’s a longer growing season in the higher latitudes? If cross-polar shipping slashes transportation costs? If winters are milder — more pleasant, even — in Chicago, Moscow and Beijing? We may all be in this together, but there are going to be winners and losers. That’s something they should talk about in Copenhagen, too.

Cue the boys from Minnesotans for Global Warming.