Every time I slip into the ocean, it's like going home.

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.

It isn't too late to shift from the swift, sharp decline of ocean systems in recent decades to an era of steady recovery. There is time, and there is a growing awareness, which is the best way to counter indifference. People who know might care.

Fortunately, we know more about the problems that we have than in all preceding history. We know now the consequences of the things that we put into the air, into the water - of the way we treat life on Earth.

The very energy sources that have gotten us to where we are now are also, if we continue doing what we're doing, a shortcut to the end of all that we hold near and dear.

By the end of the 20th century, up to 90 percent of the sharks, tuna, swordfish, marlins, groupers, turtles, whales, and many other large creatures that prospered in the Gulf for millions of years had been depleted by overfishing.

The concept of 'peak oil' has penetrated the hearts and minds of people concerned about energy for the future. 'Peak fish' occurred around the end of the 1980s.