Not too long ago I was watching a show on Discovery or National Geographic or one of those other nerdy stations I used to watch when I had cable TV.
The show was talking about how the evolution of human intelligence can be explained via climate change. To simplify and summarize, every time the climate changes, the smart ones survive. You can read a pretty good description of it on wikipedia's "Evolution of Human Intelligence".
For example: About 2.6 million years ago, the earth entered an ice age. This caused the forests in North Africa to die out and be replaced by grasslands. The smart primates vacated the dying trees in order to survive. Some even learned to walk on two legs. There are several more examples. You can read the link above.
Most recently, it has come to my attention that we, intelligently evolved primates, are actually causing, to some extent, the climate to change.
Thus, if you look at the silver lining, we are killing off the stupid ones so the smart ones can evolve. God bless Al Gore.