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.

The science is crystal clear: we humans are the primary cause of global warming, and we face a bleak future if we fail to act quickly.

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.

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.

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.

Replacing half of the U.S. ground-transport fuels with hydrogen from wind power by 2050, for example, might require 1,400 gigawatts of advanced wind turbines or more... replacing those fuels with electricity might require less than 400 GW.

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