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

The image of Earth from space transformed our view of ourselves. It is maybe the most important image that exists - because we can see ourselves in context in a way that otherwise would be really hard to explain. It should inspire us to wonder about it, to want to know everything we can about it and do everything we can to take care of it.

Humans have always wondered the big questions, "Who am I? Where have I come from? Where am I going?" It's part of human nature. It's perhaps the underpinnings of religion.

We are not only warming the ocean and the planet as a whole, but we are also acidifying the ocean and changing its chemistry.

Ten percent of the big fish still remain. There are still some blue whales. There are still some krill in Antarctica. There are a few oysters in Chesapeake Bay. Half the coral reefs are still in pretty good shape, a jeweled belt around the middle of the planet. There's still time, but not a lot, to turn things around.

The sudden release of five million barrels of oil, enormous quantities of methane and two million gallons of toxic dispersants into an already greatly stressed Gulf of Mexico will permanently alter the nature of the area.

There's a vested interest in trying to keep people smoking cigarettes.