A good question:
Would global warming be so bad? - CSMonitor.com: "What has always troubled me the most with the view that we needs to stop 'climate change' in the form of 'global warming' is the idea that it would be bad if the Earth became warmer.
Sure, that could be negative in some areas for some reasons, but it would also be beneficial in other areas for other reasons. Suppose for example that Antarctica, or at least parts of it, would become habitable due to a warmer climate, wouldn't that be a good thing that could possibly outweigh possible problems elsewhere?"