The problem with the Global Warming theory is that scientist don't know for sure if is normal for the planet to change drasticly it's weather paterns. Study from ice at the poles indicates that many changes occurred every 10,000 years or so. We are surely due for a drastic change if the studies are correct.
The good news is that many of us would most like not see it. It could take another couple hundreds of year for the real BIG changes to come our way.