Well-established theories collapse under the weight of new facts and observations which cannot be explained, and then accumulate to the point where the once useful theory is clearly obsolete.

The truth is that we're at a critical juncture in the history of our species and if we don't act soon, we could inhabit a world we don't recognize anymore. But the most important truth is that we are capable of stopping climate change before the worst of its consequences are locked in. The solutions exist - all we need is the will to do something about it.

Every day we put another 110 million tons of global warming pollution into the sky as if it's an open sewer, and it's still building up. And the scientists tell us it's a race against time. We've stabilized emissions globally now for the last three years, but they need to start coming down quickly. We've got the momentum, we've got the wind in our sails, we're gonna win this.

When you're going through an emotional experience and you're focussed completely on what's happening, you can't even spare any attention that the camera's there.

The global warming deniers persist in this air of unreality. After all, the entire north polar icecap, which has been there for most of the last 3 million years, is disappearing before our eyes. Forty percent is already gone. The rest is expected to go completely within the next decade. What do they think is causing this?

The Congress is virtually incapable of passing any reforms unless they first get permission from the powerful special interests who are most affected by the proposal.

I've learned the importance of changing people's minds at the grassroots level so that whoever does run will have a much better chance of encountering public opinion that reaches a critical mass and brings about a change not only in White House policies but in the Congress and in the state legislatures and all around the world.