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.

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 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.

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.

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.

Often we need to use policy to level the playing field, or to be sure that a technology is managed in a responsible way.

You have to be willing to spend an awful lot in that R&D phase before you see the benefits. When you look at the companies that have really won customers over in technology - say, Apple and Google - you find that they spend billions of dollars on R&D each year, often spending that much on a product before they ever make a dime back in profits.