Some of these species that are now no longer with us were killed off by a fungal disease that was moved around the planet by people.

The Earth is big. There are huge natural forces that have worked over geological time. But it turns out, when you look carefully at the geological time, you can't find anything like us.

You've got to do everything, everything's got to be pointing in the same direction and you've got to really turn this whole economic engine from one that's based on fossil fuels to one that isn't.

Several decades ago, a detachment of the American right cut itself loose from reason, and it has been drifting along happily ever since. If the birthers are more evidently kooky than the global-warming "skeptics" or the death-panellers or the supply-siders or the Swift Boat Veterans for Truth, they are, in their fundamental disregard for the facts, actually mainstream.

Increasingly developing countries are asking for aid to help deal with the consequences of climate change, which we don't want to give.

Mitochondrial DNA, which is a sort of abridged version of DNA, is passed directly from mother to child, so it's something that can be looked at to trace matrilineal descent.

It is estimated that one-third of all reef-building corals, a third of all fresh-water mollusks, a third of sharks and rays, a quarter of all mammals, a fifth of all reptiles, and a sixth of all birds are headed toward oblivion. The losses are occurring all over: in the South Pacific and in the North Atlantic, in the Arctic and the Sahel, in lakes and on islands, on mountaintops and in valleys.