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.

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.

In fact, the early demographer Thomas Malthus believes that the only way the human population would ever check itself was by running headlong into a disaster, like a pandemic or famine. Sometimes we get so frustrated with the slowness of human political processes that we wish a giant flaming rock would solve the problem for us.

One reason that we're so adaptable is that humans are excellent tool users and homebuilders. When our environment doesn't provide us with something that we need, we try to make it ourselves out of whatever is available, whether that's rock or wood or ore or DNA.

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.

think we're still stuck in that agricultural mindset, where we imagine that we can shape the Earth. Sure, we can do that. But the Earth has the power to shape us much more powerfully. To survive climate change, we'll have to realize how dependent we are on our ecosystems for our own survival.

To be fair, if we are having a mass extinction, we're in the early stages of it. I think it's knowing facts like that which has made me less fearful about the future. Mass extinction is a long, complicated process that we are just now beginning to understand - and likewise, we are just beginning to understand how we might prevent one.