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.

I love music of all kinds, but there's no greater music than the sound of my grandchildren laughing; my kids, too.

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

When you think about the real cost of so-called cheap energy that has driven our prosperity to unprecedented levels, for some of us, to our horror, we've realized that this has the potential for burning brightly and then snuffing out.

We are depleting this immense diversity and abundance of life, and it matters tremendously for the future of the planet.

When I was 12, we moved from New Jersey to Florida. The Gulf of Mexico was literally my backyard. Every day, I could see the ocean. At low tide I went out and played in seagrass meadows that used to come right up to the shore, filled with tiny seahorses, pipefish and soft corals. There was so much life! But then I witnessed the change, the loss of the shoreline, the loss of the mangrove trees, the loss of the seagrass meadows. Shallow bay areas were turned into parking lots.