I try to be realistic and pragmatic. I have a lot of hope for humanity as a species, but obviously as individuals we can be extremely flawed. We may have to go through some very terrible times in the near future, even if we ultimately survive as Homo sapiens.

Even though I now know that it's likely the Earth will suffer through mega-volcanoes or meteor strikes that could take out millions or billions of people, I feel less anxious about it because I actually understand what the threats are. There's nothing like researching something exhaustively to make it less terrifying.

I think that humans are also set up to survive. We're not as small as rats, but we make up for that by being intelligent enough to make our own hiding places and to adapt to new habitats, even if they are changing very quickly. We have an enormous population, and can afford to lose billions of people without suffering very much as a species. Indeed, some would say losing five billion people would be good for the planet - I disagree with them, but can't deny that we would do just fine if there were two billion of us or even one billion.

A lot of environmental and biological science depends on technology to progress. Partly I'm talking about massive server farms that help people crunch genetic data - or atmospheric data. But I also mean the scientific collaborations that the Internet makes possible, where scientists in India and Africa can work with people in Europe and the Americas to come up with solutions to what are, after all, global problems.

Humans are a great survivor species but our survival will be pretty grim if all of the plants and animals we depend on die out. That's why any human survival strategy has to include a plan to maintain our environment roughly in the state that it's in now.

Obviously it depends on how you define a word like "evolution," because of course we have been evolving - both biologically and culturally - in relation to the natural world for hundreds of thousands of years.

The fact that we have been able to perturb the carbon cycle with our industrial revolution is evidence of how vulnerable we are - because when we destroy our environments, we destroy our food and energy supplies. In short, we destroy ourselves.