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.

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

Today, our incentives aren't set up well - you can make a lot of money burning fossil fuels, digging up wetlands, pumping fossil water out of aquifers that will take 10,000 years to recharge, overfishing species in international waters that are close to collapse, and so on.

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.

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.

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.

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.