We've got to alter our fossil fuel dependence and go to other energy sources.

If you think the ocean isn't important, imagine Earth without it. Mars comes to mind. No ocean, no life support system.

Since I began exploring the ocean in the 1950s, 90 percent of the big fish have been stripped away. Tuna, sharks, swordfish, cod, halibut, you name it, the numbers have just collapsed. Also, about half of the coral reefs are gone, globally, from where they were just a few decades ago.

Earth as an ecosystem stands out in the all of the universe. There's no place that we know about that can support life as we know it, not even our sister planet, Mars, where we might set up housekeeping someday, but at great effort and trouble we have to recreate the things we take for granted here.

Most of life on Earth has a deep past, much deeper than ours. And we have benefited from the distillation of all preceding history, call it evolutionary history if you will.

What we put into the atmosphere in terms of burning fuel is unprecedented.

We have an atmosphere that is roughly 21% oxygen. The rest of it is largely nitrogen. There's just enough carbon dioxide (CO2) to drive photosynthesis. That has been, throughout the history of our species, pretty stable. Until recently.