Six Degrees

I've been seeing quite a bit of discussion on the issue of the dangers of climate change, so I thought I would throw my $.02 on the topic. I've been reading articles about carbon emission and climate change.... and the conventional wisdom seems about right. It is hard to know for sure how much C02 is required to get various levels of temperature change but most of the models seem sensible.

The next issue is what is the effect of that climate change. Mark Lynas' Six Degrees is an attempt to put together a series of "what if" scenarios regarding temperature change. The book is scientific but heavily biased towards disaster. This is unfortunate because the book is really unique in trying to put together a good picture of what long term climate change means and address issues of positive feedback. Positive feedback is one of the great dangers. An example is as the earth warms there is less ice which reduces the reflectivity of the earth which increases the tempature even further. But there are also additional sources of carbon that are released as the earth heats, many environmentalists are of the opinion that we can see cycles like:
3 degrees of warming causes the amazon to dry
The Amazon trees aren't designed to be dry so this causes massive forest fire, i.e. the forest burns to be replaced by different vegitation
That releases so much carbon that we hit 4 degrees.
At 4 degrees of warming the carbon under the permafrost is released which casues 5 degrees of warming
At 5 degrees of warming the ocean bottom warms and we get releases of hydrocarbons stored at the bottom of the ocean which gets us 6 degrees of warming

That is they believe there are no equilibrium points close to our current temperature. Lyons does a nice job of explaining these sorts of positive feedbacks and documenting them. He introduces one to the literature on environmental impact quite well.

Where I think he fails, is that he is generally pessmistic well beyond what is called for. For example he frequently talks about drought leading to crop loss, when describing changes in waterflow that humans have dealt with successfully for 6000 years. In a world with much more rain, more moderate tempatures and excellerated plant growth due to excess carbon he tries to make a case for famine and it implausible.

A perfect example of this is his description of why plants can't migrate north fast enough, not counting the fact that humans can move plants north, particularly crops as fast they need.

So I can recommend the book because it seems to be the best overview of the literature it feeds the very feeling many have that the environmentalist movement is screaming chicken. What we need is a version of six degrees which is written assuming aggressive adaption.