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.

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

When it comes to trying to manage how our entire planet-wide market and all the people and businesses in it deal with nature and our natural resources - we first and foremost need to change the incentives.

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.

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.

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.