There are a lot of things that we could do to minimize what we're doing, but we're not getting back those frogs that I saw that no longer exist.

Most of the world's major waterways have been diverted or dammed or otherwise manipulated - in the United States, only two per cent of rivers run unimpeded - and people now use half the world's readily accessible freshwater runoff.

Though it might be nice to imagine there once was a time when man lived in harmony with nature, it’s not clear that he ever really did.

Letting things slide is always the easiest thing to do, in parenting no less than in banking, public education, and environmental protection. A lack of discipline is apparent these days in just about every aspect of American society. Why? This should be is a much larger question, one to ponder as we take out the garbage and tie our kids' shoes.

When you drive to the grocery store, your intention is not to change the world, it just happens to have that impact. So we've done a lot of things without even realizing it, and yes, just being unusual, as you say, does not put you above, in a sense, any of the other organisms with whom we share this planet.

One of the reasons that people, many people, many environmentalists are critical of President [Barack] Obama's policies towards global warming is on the one hand he says the right things and he says he's committed to trying to reduce our current emissions.

Humans will eventually become extinct. People treat that as a radical thing to say. But the fossil record shows us that everything eventually becomes extinct. It depends what "eventually" means. But the idea that were going to be around for the rest of global history...I don't think there's any scientist who would suggest that is true. It could be millions of years from now. We may leave descendants that are humanlike.