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.

Sometimes it's hard to take everyday concerns seriously when you think about vanished ecosystems that existed 300 million years ago and were eradicated by giant explosions. My goals haven't changed, because my goal has always been to save the 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.

We have converted huge swaths of land and ocean into human habitats where we live and grow food and harvest energy. But there's been a sea change in the past century.

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.

So science alone cannot solve this problem [mass extinction of humans]. It's something that we can only tackle by bringing science together with culture, economics, and even politics.

I disagree that we need to contemplate eliminating ourselves in order to move forward. Sure, I think a good dystopian story can serve to steer us on the right path toward a better world. But we also need stories that offer solutions to our problems that are realistic, and workable today.