You must become a climate champion, a single-issue voter. You must take whatever action you can. You must use whatever influence you have wherever it would make a difference, even if it is only to educate the people around you.

By the end of the third decade of this century, all of American life - politics, international relations, our homes, our jobs, our industries, the kind of cars we drive - will be forever transformed by the climate and energy challenge.

Some 3 million years ago, when the earth was a little more than 3°C warmer than preindustrial levels (about 2.2°C warmer than today), Antarctica had far less ice and sea levels were a stunning 25 meters higher than today. If we stay on our current emissions path, the planet will almost certainly be that warm by the century's end.

I've always believed that you should stick as closely to the science as possible. And my biggest advice to reporters has been, if you're doing a climate story, talk to climate scientists. The best climate stories are done by the people who talk to climate scientists.

The first few feet of sea-level rise alone will displace more than 100 million people worldwide and turn all our major Gulf and Atlantic coast cities into pre- Katrina New Orleans - below sea level and facing super-hurricanes.

Do believe that if we fail to act in time, it will be the single biggest regret any of us has at the end of our lives.

Time is short. We have at most a decade to sharply reverse course.