Want to spend a few evenings hiding under the covers in abject fear? Might we suggest the new nonfiction book about global warming, Six Degrees: Our Future on a Hotter Planet, released last week by National Geographic Books.

Author Mark Lynas starts with the Intergovernmental Panel on Climate Change's official estimate – that the Earth's average temperature will rise by up to 6 degrees Celsius (10.8 degrees Fahrenheit) by the year 2100 – and explains what the world will look like if the temperature rises 1 degree, 2 degrees and up through 6 degrees Celsius (1.8, 3.6 and 10.8 degrees Fahrenheit; all subsequent references in degrees Celsius). It's based entirely on peer-reviewed science; Lynas spent several years combing through academic journals in search of relevant articles, and then put the pieces together for this planet-wide view.

Wired News spoke with Lynas about alarm bells and alarmism, what needs to happen to forestall civilization's doom and why his research didn't turn him into a pessimist.

Wired News: It's really striking – with just 1 degree of warming, the world is a much sadder and more desperate place, with "megadroughts" across the American west, dying coral reefs and stronger hurricanes. When you put together that picture of a 1-degree-warmer world, were you surprised at how dramatic it was?

Mark Lynas: Well, we're mainly talking about the continuation of current trends – we're already seeing the first signs of these things. The United States is already much drier; there's an extended drought going on at the moment, and has been for many years. Coral reefs are already dying. It's a world that we're going to have to get used to, because it's pretty much unavoidable even as we speak.

WN: You write that one paper published in the scientific journal Nature in 2000 helped convince you that this book needed writing. Can you briefly explain what that paper was, and why you reacted so strongly to it?

Lynas: It was a paper publishing the outputs of a computer climate model. What was so striking about this particular model was it simulated the dieback of the Amazon rain forest. Not all models of the Amazon show this – some don't show it at all. But if this becomes a reality, we would lose the most precious biosystem on the planet, and an ecosystem that drives the world's weather. And I thought this was something that the world should be more aware of, not buried in an academic journal, even a journal as prestigious as Nature. It should be driving the priorities of politicians. It should be the top of everyone's priority list.

WN: Obviously you care deeply about this issue, and are dedicated to waking up the public to this common threat we're all facing. Did that dedication nudge you towards lingering on the worst-case scenarios, or playing up dangers even when the science on a particular issue isn't yet settled?

Lynas: That's something I was very aware of trying to avoid. Particularly given my background as a campaigner and environmentalist, it would be very easy for me to be accused of hype or alarmism. With that in mind, I wanted to stick very closely to the science. And I have not had any scientists complain about how I represented the science. I've had a very positive response.

Having said that, people do focus on the worst-case scenarios. And I think people are entitled to understand the worst-case scenario. In the same way you're entitled to buying fire insurance on your house, without worrying every day that your house is going to burn down.

WN: To stick with that example of the possible collapse of the Amazon rain forest, you write later that the modeling results about the Amazon are inconclusive – one study found that only six out of 11 models predicted a drastic reduction in rainfall in the Amazon. Do you think it's fair to spend so much time describing that potential collapse, when the chance of that happening currently seems to be about 50-50?

Lynas: But a 50-50 chance of an impact like that is quite high. If they told you there's a 50-50 chance that you're going to die on an airplane, you probably wouldn't get on it. The chances that people are willing to accept when it comes losing their lives is something like one in a million. But they'll ignore the fact that there's a 50-50 chance of losing the world's biggest and most precious ecosystem.

WN: So you're saying that we can't wait until the science is settled to act on this.

Lynas: The science will only be settled when you can look, and say whether the Amazon has died or not. And obviously, by then it's far too late.

WN: By the time you get to a 3-degree-warmer world, we're talking massive crop failures across the globe, and mass migrations. Since you stick to the science, you only briefly speculate on what the societal impacts would be – but do you think war, upheaval and chaos would be inevitable?

Lynas: No, it's possible we could have a very positive, philosophical approach where we all come together and try to get through this the best we can. There's no precedent for humans working together on a global scale, but this could be the first. I'm not necessarily pessimistic about this.

WN: When you get to the chapter on what life would be like on a planet that is 6 degrees warmer, you write that it gets harder to find scientific studies that make predictions. It seems almost like we humans just can't comprehend planetary changes on that scale. Is it a failure of imagination?

Lynas: Slightly. But it's also the conservative nature of the scientific community. I don't think scientists want to be accused of being alarmist either, so they're very careful to remain on the cautious side of things. Six degrees – that's on the worst-case scenario end of the scale predicted by the IPCC. But if it's on the scale at all, it's worth looking at. That's why I have to wind the clock back tens of millions of years to warmer periods in the planet's history, to try to get an idea of what it would be like.

WN: In the last chapter, called "Choosing Our Future," you talk about how, if we alter our behavior, we can aim for a "safe landing" in a 1- or 2-degree-warmer world. What action did you determine needs to be taken?

Lynas: We need to see greenhouse gas emissions peak in the next decade or so, preferably by the year 2015, and emissions reduced by 85 percent by 2050.

WN: You wrote in the introduction that you were surprised to discover that some people find this subject matter incredibly depressing. You don't get depressed by this?

Lynas: Everything from 2, 3 degrees upwards is a "what if" scenario. When people come to me and say that they stopped reading at 4 or 5 degrees because it was getting too depressing, I say, "But you shouldn't be depressed, because that may never happen. There's still something you can do about it!"

Whether you get depressed depends on how likely you think this is to happen. It comes down to your view of humankind. If you think humans are innately selfish, that they don't care about the future and just care about driving flashy cars, then you're going to get depressed. If your view of humanity is that we're an intelligent species, that we can come together on an international basis and find solutions to this problem that include all the world's people, then you'll have more hope. It depends on your personality, and on your politics.