|I think the main cause of hurricanes is that warm moist sea air rises,
|causing an inflow of surrounding air. The heat differential that
|supplies the energy is vertical, the difference between ground level
|and stratospheric air. The effects of global warming on this
|differential is definitely non-trivial.
You need to have lots of warm sea water (>27 degress C) to get a hurricane. Therefore hurricanes only appear in places north or south of the equator which do have direct sea access to the equator. A hurricane tend to blow away :-) when it hits higher ground.
So... global warning would mean more warm sea water, and thus extended hurricane belts.