Six degrees: our future on a hotter planet

Global Warming is much in the news nowadays and so it should be - most of the other problems we have pale into insignificance compared to what global warming might bring. In this book Mark Lynas tells the reader just how bad it might get.

The book is divided into chapters from 1° to 6°, each describing what is likely to happen with that degree of warming. A rise of 1 degree celsius doesn't seem much, but it means that many mountain glaciers will shrink, leading to water shortages around the rivers they feed. Fragile ecosystems, such as that of the Queensland Wet Tropics rainforest, are also likely to be hit badly. The circulation of Atlantic might also be disturbed enough to greatly change the climate in the UK. 2° will mean that the heatwaves in Europe which occured in 2003, and which were responsible for a large number of deaths, will come to be thought of as normal. Also there will be significant shrinkage of the ice caps. In fact this temperature would probably mean that they would disappear altogether over thousands of years - and they'll go much quicker it it's any warmer. I'll jump ahead in the book a bit here, and point out that even if we go ahead with most of the plans to limit global warming, we're still likely to have a temperature rise of 1-2 degrees. And it gets worse. 3° means the destruction of the Amazon rainforest, as well as rivers such as the Indus drying up for much of the year. There'll also be more devastating storms, which, combined with the increase in sea level is likely to require an endless struggle to keep floods out of cities near the coasts. This temperature rise will also mean it will be harder to grow the food we need.

Four degrees of warming will lead to the huge sea level rise we've seen in the movies, and to the desertification of areas such as Southern Europe. At 5° many places will become uninhabitable, but then if it gets that bad then it's not likely to stop there. Positive feedback mechanisms such as the release of methane hydrates will mean the temperature will go on increasing. This brings us to 6°, which may well lead to a mass extinction - worse than that at the end of the Permian, since it will happen so much quicker. Humans are adaptable creatures, and would be likely to survive, but probably only as small, disconnected groups.

In the final chapter Lynas looks at what we can do to avoid the worst excesses of global warming (It looks like we're almost certain to have a 1-2° rise in temperature). Dealing with the car culture is an obvious choice - as Lynas points out it causes many other problems apart from global warming. Interestingly, some people have seen this as a way to dismiss it. If (and it's a big if) there was a way to get our energy from non-carbon sources, would Lynas then fully embrace our consumer culture? No? Then global warming can't be so important. So what this seems to be saying is that since there are several reasons not to drive, rather than just one, then you can ignore all of them and continue your love affair with the car. This certainly looks like clutching at non-existent straws.

That said, I did feel that Lynas was overly dismissive of techno-fixes for global warming. Of course we don't want to pin our hopes on fantasies (My idea would be giant solar powered refrigeration units in Antarctica converting the CO₂ into dry ice), but Lynas seems to have his doubts about tested technologies as well. Nuclear power is 'controversial', and even solar power seem to have its problems . Lynas says that there are shortages of the silicon components needed to build solar panels. Now it's true that production of solar panels has lagged behind demand in the last few years (it's now catching up), but this is hardly a 'resource constraint' as Lynas says. I mean, what is our planet made of - the Earth's crust is mostly silicon dioxide.

I didn't feel, though, that Lynas was trying to push a hidden political agenda, rather that the chapter didn't have much of an agenda at all. It's true that he does have a table relating time of peak oil use to probable warming, and he gives details of Socolow and Papala's wedge strategy, but overall I found the vagueness of the last chapter a bit of a let down after the precision of the first six. I had similar misgivings about last year's entry for the Royal Society Prize, The Rough Guide to Climate Change. I suppose what I'm looking for is a book which goes into much more detail about what the options are and what effect each would have. For example, should I think of giving up gas central heating? Maybe one of the books entered for the 2009 Royal Society Prize will have the answer.

I guess, though, that I shouldn't criticise Six degrees for not being a different book. It wouldn't be my choice to win the 2008 Royal Society Science Book Prize (in fact it was the judges choice), but it does have plenty going for it. Certainly Lynas emphasises that business as usual is simply not an option and that we are not powerless to tackle the problem. One of the things I liked about this book was the way that Lynas packed in a great amount of detail, which can't just be dismissed with a few platitudes, but did so in a way that kept the readers interest. Hence I feel that this is likely to be an important book in spreading the message of what we are likely to be in for.