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.

I've spent thousands of hours under water. And even in the deepest dive I have ever made, 2.5 miles (about 4 kilometers) down, I saw trash and other tangible evidence of our presence.

Use your power to do whatever it takes to secure for humankind an enduring place on this little blue speck in the universe - our only hope.

It's mainly the high-end luxury market now that drives much of the fishing in the sea. It's not feeding the starving millions. It's feeding a luxury market.

We still have 10 percent of the sharks. We still have half of the coral reefs. However, if we wait another 50 years, opportunities might well be gone.

It's an appreciation for life generally, every bit of life, the smallest creature that lives in the intestines of termites that make termite life possible - to the leaves that turn out oxygen and grab carbon dioxide and with water make simple sugars that feed much of the world. I mean, these are everyday miracles.

No creature on Earth ever has organized themselves in ways that we have, with the capacity to alter the nature of nature the way we have.