The great political tragedy of our time is that conservative leaders in America have chosen to use their superior messaging and political skills to thwart serious action on global warming.

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.

Ideology trumps rationality. Most conservatives cannot abide the solution to global warming - strong government regulations and a government-led effort to accelerate clean-energy technologies in the market.

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.

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.

Would PBS go so far as to give air time to an even more extreme kind of disinformer, a Holocaust denier?

The entire western Siberian sub-Arctic region is melting, and it has all happened in the last three or four years.