America's political system has evolved over the last 50 years in ways that have enhanced the power of business lobbies.

We can't negotiate the facts. We can't negotiate the truth about the situation. And for those who are too fearful to finish, it can be done and must be done. Make sure we succeed, . . . It is wrong for this generation to destroy the habitability of our planet and ruin the prospects of every future generation.

The entire North Polar ice cap is disappearing before our very eyes. It's been the size of the continental United States for the last 3 million years and now 40 percent is gone and the rest of it is going.

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.

I'm sorry I ever invented the Electoral College.

The cumulative amount of man-made global pollution that's in the atmosphere now traps as much extra heat energy every day as would be released by 400,000 Hiroshima-class atomic bombs exploding every day. It's a big planet, but that's an awful lot of energy.

When it comes to climate, we can all make a big difference.