We have been getting rich by depleting all our natural stocks - water, hydrocarbons, forests, rivers, fish and arable land - and not by generating renewable flows.

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.

The United States could dramatically reduce its carbon emissions per kilowatt-hour without raising its overall energy bill.

When people ask me what they should do, I reply, "Get informed, get outraged, and then get political."

Protecting dozens of major coastal cities from future flooding will be challenging enough-rebuilding major coastal cities destroyed by super-hurricanes will be an almost impossible task.

On our current path, all our great Gulf and Atlantic coast cities are at risk of meeting the same fate as New Orleans.