Ocean acidification - the excess carbon dioxide in the atmosphere that is turning the oceans increasingly acid - is a slow but accelerating impact with consequences that will greatly overshadow all the oil spills put together. The warming trend that is CO2-related will overshadow all the oil spills that have ever occurred put together.

When I arrived on the planet, there were only two billion. Wildlife was more abundant, we were less so; now the situation is reversed.

The Exxon Valdez spill triggered a swift and strong response that changed policies about shipping, about double-hulled construction. A number of laws came into place.

Success underwater depends mostly on how you conduct yourself. Diving can be the most relaxing experience in the world. Your weight seems to disappear. Space travel will be available only to a few individuals for some time, but the oceans are available to almost everyone - now.

Historically, girls have not been encouraged to be scientists, to be explorers, and there's a social kind of constraint, of course. Having the responsibility, a disproportionate part of the responsibility, for caring for families, caring for children. I know this challenge from firsthand experience because I have three children and four grandsons.And some of the time I have spent as a scientist and as an explorer has meant choosing to not be with my children and grandchildren as much as I might otherwise have done had I not been a scientist, an explorer.

This is a living planet. Look around. Mars, Venus, Jupiter. Look beyond our solar system. Where else is there a place that works, that is just right for the likes of us? It has not happened just instantly. It is vulnerable to our actions. But it's the result of four and a half billion years of evolution, of change over time. And it changes every day, all the time. It would be in our interest to try to maintain a certain level of stability that has enabled us to prosper, to not wreck the very systems that give us life.

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.