When I write a scientific treatise, I might reach 100 people. When the 'National Geographic' covers a project, it communicates about plants and fish and underwater technology to more than 10 million people.

There's plenty of water in the universe without life, but nowhere is there life without water.

Globally sharks have been killed for their fins, for their cartilage, for their livers, for their meat. But mostly what has driven some species of sharks to near extinction - including the hammerhead shark - is the new luxury taste for shark fin soup.

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.

In the past few decades, Earth's natural systems have endured more pressure than in all preceding human history.

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 personally have stopped eating seafood.