'Global warming' isn't really a good term anyway. It's really 'climate change'. Warming is an overall effect when looked at globally, but that could make it colder in some places, hotter in others, because it can affect atmospheric and oceanic patterns, and many local weather conditions are driven or heavily influenced by those patterns.

We here in the Silicon Valley area have our wonderful climate because there's a cold ocean current that comes up from the bottom just off the coast. So basically we have a huge air conditioner sitting on the beach. If that were to change, I bet that it would become pure dessert here and people would bail out at a rapid pace. I'm not sure if that current is one that would be in danger of being influenced by current trends or not. Hopefully not.