Meat reared on land matures relatively quickly, and it takes only a few pounds of plants to produce a pound of meat.

It's taken us a short time to change the nature of nature. In my lifetime, more change than during all preceding human history put together.

I hope that someday we will find evidence that there is intelligent life among humans on this planet.

Ice ages have come and gone. Coral reefs have persisted.

Any astronaut can tell you you've got to do everything you can to learn about your life support system and then do everything you can to take care of it.

Ignorance is the biggest problem of all for the ocean - and for many other things as well.

For humans, the Arctic is a harshly inhospitable place, but the conditions there are precisely what polar bears require to survive - and thrive. 'Harsh' to us is 'home' for them. Take away the ice and snow, increase the temperature by even a little, and the realm that makes their lives possible literally melts away.