I decided five years ago that I wanted to truly understand, for myself, what the state of the planet was, and when I dug into it, what I found was quite different than I'd imagined.

You have to be able to generate usable energy without greenhouse gas emissions and you have to be able to do it cheaply if you want people to choose that approach.

There are really two kinds of optimism. There's the complacent, Pollyanna optimism that says "don't worry - everything will be just fine" and that allows one to just lay back and do nothing about the problems around you. Then there's what we call dynamic optimism. That's an optimism based on action.

Ozone and climate are global issues, and it's hard to find a way in which the benefits of shutting down carbon emissions are going to pay for themselves for any given power-plant, say.

In the food case in particular, one of the technologies that could help there - genetic technologies that could create better crops with higher yields and less need for water and fertilizer - is tremendously feared. Very little of that fear is scientifically grounded.

Just like you could dump oil into the Cuyahoga in the 60s and let someone else foot the bill, today you can pump CO2 into the atmosphere and let the whole world foot the bill.

Often an idea has impact far larger than the person who originated it.