The most serious result of global warming would be winter not depositing enough glacial mountain ice, and summer melting it off too quickly to last year-round. This would cause severe summer droughts, which in turn cause famine and violence over remaining freshwater.
As an example we've been directly observing for a while, Pakistan and India are getting hit by this really hard. Dwindling Himalayan glaciers supply a good deal of both countries' water supply, and they really don't need any more reasons to be at each other's throats. In addition, polar melt causes a lot of Pakistani lowland to be submerged (avg. ~80 acres a day in Sindh), displacing a lot of residents and agriculture.
The problem is "self-solving" in a really horrible and sociopathic way, in that humans will effectively cull their own population and demand by warring over dwindling resources. Note, though, that rich industry magnates would be on top of that catastrophe, and thus have no incentive to stop causing the problem. The fact that it isn't
an extinction-level problem is in many ways worse than if it was and everyone on the planet had a personally compelling reason to cut it out.
edited 17th Dec '13 8:28:37 PM by Pykrete