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.

In 2003... the White House conspired with an oil-company funded think tank to block a major government scientific report that sought to spell out the dangers of climate change to Americans.

If the politics of inaction and delay that have triumphed in this country continues for another decade, then Planetary Purgatory in the likely future facing our country before midcentury - probably in your own lifetime.

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

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.

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 moral grounds, I think that if you believe a certain outcome is a very possible outcome, you have an obligation to tell people that. With global warming, the probability of a bad outcome if we stay on our current emission trends is incredibly high. If you know a bad outcome is likely to happen, what right do you have not to communicate that? You go into a doctor's office, what are they going to do - not tell you the diagnosis?