I think the environmental movement is now so large and diverse that it's hard to talk of it as a single entity.

On almost every environmental issue I care about, in fact, I've been wrong at one point or another. I used to think that climate change was no big deal, that most environmental problems were massive exaggerations, that oil reserves were effectively unlimited, and more.

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

We have climate change caused by greenhouse gas emissions, mostly from human power and transportation infrastructure. At the same time, we have 2 billion people who live in energy poverty.

If you want to feed the planet and keep the forests we have, you need to be able to grow roughly twice as much food per acre around the world. How do you do that? New technology.

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.

I was much more of a naïve techno-optimist than I am now. I still believe that technology can help us come out of this situation with a richer humanity with less impact on the planet, but now I think it has to be paired with effective policy in order to achieve that.