Very skeptical about global warming, and as an Earth Sciences graduate this short-term view (less than about a million years) becomes a bit irrelevant to the world. Nature will recover, evolve to take advantage of the new environment when I am long gone. So minimize our impact (Americans - get real! Each yank preoduces three times the carbon dioxide of each European) but don't panic. We are in an ice age, won't harm the planet to come out of it. May harm some people - environmentalism is not necessarily altruistic.
Anyway, many of the forcast effects of global warming are uncertain - less ice due to melting, or more evaporation, so more snow, so more ice. Maybe that would trigger a new glacial period (high albedo on ice reflects sunlight, cooling the planet).