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.

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.

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.

People still do not understand that a live fish is more valuable than a dead one, and that destructive fishing techniques are taking a wrecking ball to biodiversity.

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.

The Arctic is an ocean. The southern pole is a continent surrounded by ocean. The North Pole is an ocean, or northern waters. It's an ocean surrounded by land, basically.

Some experts look at global warming, increased world temperature, as the critical tipping point that is causing a crash in coral reef health around the world. And there's no question that it is a factor, but it's preceded by the loss of resilience and degradation.