The age of printed pamphlets and political essays has long since been replaced by television, a distracting and absorbing medium which seems determined to entertain itself more than it informs and educates.

There's such a wide variation in tax systems around the world, it's difficult to imagine a harmonized CO2 tax that every country agrees to. That's not in the cards in the near term. But the countries that are doing the best job, like Sweden, are already doing both of these. I think that eventually we'll use both of them but we need to get started right away and the cap-and-trade is a proven and effective tool.

We the human species, are confronting a planetary emergency-a threat to the survival of our civilization that is gathering ominous and destructive potential...the earth has a fever. And the fever is rising...Indeed, without realizing it, we have begun to wage war on earth itself.

I drive a hybrid, and we've changed our light bulbs and windows and installed solar panels and geothermal ground source heat pumps and most everything else.

The planet has a fever. If your baby has a fever, you go to the doctor. If the doctor says you need to intervene here, you don't say, `Well, I read a science fiction novel that told me it's not a problem.'... You take action.

Where solar energy is concerned - and wind energy and battery storage and electric vehicles and efficiency technologies - that is what we are now seeing. So, yes, I'm very optimistic, but anyone who works on the climate crisis has an internal struggle between hope and despair. I won't deny that, but hope has always prevailed in my outlook.

What we take for granted might not be here for our children.