Scientists never stop asking. They're little kids who never grew up.

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.

The ocean is dying, and we have no place to escape to if this experiment doesn't go in our favor.

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

We couldn't go to the moon on whale oil. We don't have the capacity yet to consider doing such things as harnessing current sunlight. We're burning ancient sunlight in order to get us to where we now are. But it's costly.

If you make the choice to just go with the flow, that is a choice to make a difference in a negative way.

We've got to alter our fossil fuel dependence and go to other energy sources.