Slashdot | Astronaut: 'Single-Planet Species Don't Last'
Slashdot thread on a John Glenn article. The article references are good, the Slashdot commentary is feeble (I think the rise of blogs has killed Slashdot's commentary quality). The Economist had a good issue on this years ago -- they came to the same conclusion about the probability of a meteor annihilation vs. airplane crash.
Glenn exaggerates a bit. Sharks, for example, have been around a long time. Humans are pretty resilient rats and might survive a lot of harm. Our civilization, however, would not.
On the other hand, we have much bigger problems than meteors ahead in the next forty years.