I would want us to start our quest to survive mass extinction by rethinking how we build cities. Cities should be commonplaces of production, rather than consumption - they should be producing food, and fuel.

GMO agriculture will probably save the world in this century. But in the developed world, where few people are haunted by the specter of famine, people are free to fetishize heirloom tomatoes and worry about the provenance of what sits on their dinner tables.

Cities should function more like ecosystems, or even metabolisms. When we build, we should be thinking about how we can integrate into the ecosystems around us, but without sacrificing all the niceties of civilization like good restaurants, concert halls, and high-speed Internet access. I'm saying that partly tongue-in-cheek, but I'm also deadly serious. The future of technology is sustainable ecology.

Part of what I wanted to do in my book was point out that we have almost reached the point where we can prevent a mass extinction with the science and technology we have today. We can build carbon neutral cities.

I would want us to start our quest to survive mass extinction by rethinking how we build cities. Cities should be commonplaces of production, rather than consumption - they should be producing food, and fuel.

Some time ago we discovered the carbon cycle - a long-term set of chemical reactions that govern climates based on how much carbon is free in the atmosphere. At that point, it became clear that humans were affecting our environments far more profoundly than we realized. By releasing so much carbon and greenhouse gas into the environment, we're making long-term changes to every aspect of the natural world.

Survivor species tend to have huge populations, so they can afford to lose many individuals and still survive as a species. They also tend to be small. If you're small, you need less food - which is great in a situation where famine is everywhere.