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The Revenge of Gaia by James Lovelock

(I've incorporated a few facts from the first chapter of another book I've been having a look at, The Last Generation by Fred Pearce

The first part of the Revenge of Gaia describes how global warming comes about and the seriousness of the situation; it then goes on to suggest measures which could make its impact slightly less catastrophic. However for now I only want to focus on the first part of the book - the mechanism of global warming.

James Lovelock is a scientist I respect because he is a maverick - he is not afraid to challenge accepted ways of thinking.

The book is based on the Gaia theory - the earth studied as a living organism (without any implication that it is conscious) because it operates as a system of feedback loops to maintain the conditions necessary for life. He was heavily attacked for putting forward this theory about 30 years ago, but has demonstrated the scientific validity of his claim, which is now accepted by the scientific community.

The set of conditions to which the system returns via feedback loops is known to mathematicians as an attractor. However if the system is pushed far away from this set of conditions it may not return to this attractor, but to a different one, with a different set of conditions, not so conducive to life. This is what is happening now, through global warming. (Attractors are part of the mathematical theory known as chaos, and I waffle on about them in a half-baked way in my review of another book, Fritjof Capra's The Web of Life)

I'm glad I got that off my chest

The problem with global warming is this: it is a positive feedback process. By this I mean that as temperature increases by a few degrees Centigrade globally, it has effects which cause a further temperature increase. It's like a fire feeding itself.

For example, a lot of plant life, which is the primary absorber of Carbon Dioxide, (the most important Greenhouse gas) will die, particularly algae in the oceans and also the tropical rainforest. At the moment the concentration of Carbon Dioxide in the atmosphere is 380 ppm (parts per million) having increased from 280 ppm at the end of the last ice age (most of that increase was during the last 30-40 years). When the concentration reaches 500 ppm (which won't take long, temperature increase changes from gradual type 1 climate change, to dramatic type 2 climate change, (a "tipping point") where there is an immediate jump of several degrees centigrade, and basically, we're screwed.

Ocean Algae
Although plant life can survive in temperatures up to 50 degrees centigrade, in the oceans nutrients are supplied to the plant-rich surface layer by mixing with the nutrient-rich deeper layers, up to 10 degrees centigrade. If the ocean temperature increases to 12 degrees centigrade, this mixing process stops, and the ocean plant life dies. This is why the oceans in tropical areas are a desert. With a small increase in global temperature, the area of ocean below 10 degrees centigrade will be pushed further North and South, and cover a reduced area, absorbing less Carbon Dioxide.

In the preface to the Fred Pearce book, he describes how the global circulation of the oceans, called the ocean conveyor is breaking down, due to the disappearance of "convection chimneys" in the Greenland Sea, and elsewhere. These are massive whirlpools where warm water from the Gulf Stream has cooled rapidly in the Arctic and sinks to the bottom where it is cycled South. There used to be 12 in this area - in 2003 only one - now I don't know.

Tropical Forest
Above 25 degrees centigrade evaporation is so rapid that soil dries out and land becomes a desert. Richard Betts of the Hadley Centre in Exeter has shown that rainforests have overcome this limitation by sustaining clouds and rain above the rainforest canopy, but a 4 degrees centigrade temperature rise would destroy the rainforest which currently absorbs a lot of Carbon Dioxide.

Melting of the Polar Ice Caps
A third major source of positive feedback is the melting of the polar ice caps. This is because the polar ice caps, being white, reflect most of the suns rays. When it all melts, the earth will absorb this heat energy, instead of reflecting it. There is a wonderful lady in her 60s called Liz who cuts my hair in the Passage Day Centre - when she war a youngster she wrote travel books, but now in her grand old age she just travels. Well, yes, last time she cut my hair, she'd just come back from a visit to Greenland - she told me all kinds of interesting things - like the local people can't live off seals and whales anymore, because they're polluted with stuff carried from the U.S. by ocean currents, but they've all got camera phones and take millions of photos of themselves fishing; also about dog society in what fundamentally is a town run by dogs in which humans are sort of tolerated. But (reluctantly) getting back to the point, she said you can just see the glaciers melting - it's that obvious - vast streams of water coming off them. A statistician would call that anecdotal evidence, and be skeptical of it, but I like it!

Melting of Permafrost
In "The Last Generation", Fred Pearce refers to the melting of the permafrost layer in Siberia, which will release billions of tons of greenhouse gases

How am I going to finish this - well, it seemed to be a very good analysis, written in clear, simple English (no rubbish about attractors by the way)- he goes on to say all these things we should be doing, which I don't think will happen, but won't get into all that now as am going for soup at the Manna Centre - excellent book - read it!