Mass Extinction #6
One of these days I should go back and take a look at the details of the first 5 mass extinctions. The last one was 65 million years ago, and the evidence for it being caused by a large impactor is pretty solid. The other ones are less clear, as far as I know. The sixth one is currently underway, and the cause is pretty clear. Joe Romm has a nice post about it [LINK]. Whenever reading Romm, one must remember that he's always presenting the worst case scenario (and as if it is inevitable), but even when one scales his arguments by 50% or so, it's not a pleasant picture. If anyone wants to skip the commentary and read the source material, it is a special issue of Phil. Trans. [LINK].