They already did global warming twenty years ago in SimEarth.
They also did it in the first SimCity, in which one of the scenarios was a future Rio where you had to deal with floods generated by rising water levels due to polar ice cap melting. (Also included were historical--San Francisco earthquake response--and wholly fictional--rebuild Tokyo after a "monster" that looked suspiciously like Godzilla rampaged through it.)
I'd start negotiating limbs for a new OS X version of SimEarth.
I'll have to buy it just so I can build a low-tax, high-pollution metropolis to tick off my virtual neighbors.
Would any publishers want to offer me a book contract for "A Year of Simulated History," where I spend an entire year writing about the process and results of doing nothing but playing the various iterations of SimCity, SimEarth, Civilization, and Axis and Allies? (I started this out tongue in cheek, but I see a really solid book proposal in here. And if any of you steal it from me, I'll simulate some really terrible fate in a computer simulation game!)