Dec 29, 2006

Revenge of Gaia

I first discovered James Lovelock's writing a decade ago when I read his brilliant "Ages of Gaia" which lays out his model of geological history. In brief, he set out to answer a conundrum in Earth Science. It is known from astrophysics that the sun is getter steadily hotter, a 25% gain since the beginning of life in the Precambrian. And yet, it is also known from geology that the mean temperature of the Earth has varied up and down within a range of a few degrees of Celsius. How can these facts be reconciled?

Lovelock's answer is the Gaia hypothesis. He proposes that the geo-chemistry and the living organisms work together as a closed system in negative feedback to regulate the Earth's climate. Negative feedback is a term from engineering; it means that if the temperature (or other variable) goes up, the system works to bring it down and vice-versa. Think of a thermostat. He names this earth regulatory mechanism "Gaia" after the Greek goddess of the Earth.

One if the chief mechanism of adjustment in the Gaia system is the carbon dioxide level in the atmosphere. In the earlier earth, when the sun was weaker, life needed more heat and the atmosphere had more CO2. Plants have been sucking it back since then to keep the greenhouse effect at precisely the desired level. If the level falls too low, the earth gets colder, vegetation dies back and CO2 builds up again. If the level gets too high, plants flourish and their action reduces the level again.

Everything nice and cozy on the old mudball until a random mutation in some apes comes along. One of these apes eventually builds a steam engine and the rest is history. The neat regulatory system of Gaia is all messed up with choking fumes.

I've just finished Lovelock's new book, Revenge of Gaia, and it's a sobering read. The short version; there's not much time left. In fact it may already be too late. Our heedless production of CO2 and our destruction of the natural environment may already have a passed a critical tipping point where global heating cannot be reversed. For example, the permafrost in the Canadian and Siberian arctic is melting, releasing methane and speeding up the process; Gaia has shifted into a dangerous positive feedback. Think of a faulty thermostat that turns the furnace on when the temperature goes up.

The future he paints is bleak. If he is right the earth system will jump into a new hotter equilibrium state. All the ice will melt, sea-levels will rise several meters. And most of the earth's remaining land surface will be semi-desert. The only habitable real-estate will be around the poles. Lovelock says this happened once before, at the start of the Eocene 55 million years ago, after what was probably a huge volcanic upsurge. This coming to a land-scape near you sometime before 2100.

Lovelock also has some critical things to say about the Green movement, which he sees as being too romantic and insufficiently guided by hard science. His critique of so-called bio-fuels is not suprising; they are basically a crock. For one thing, with current farming practises it takes about twice the fossil fuel input to grow the corn for a gallon of ethonal than if we just burnt the gas directly. For another, if all the arable land in the United States was devoted to corn production for ethanol, it would just barely meet the current consumption demand.

More surprising to some environmentalists may be his advocacy of nuclear energy. His chapter on energy sources is a very soundly argued from science. I won't reprise it all here, but it does lead to the strong conclusion that nuclear is our greenest option with present technologies. However, I was very glad to see that he put energy reduction forefront. He says that we should forget about "sustainable development" and start thinking in terms of a "sustainable retreat."

One fascinating chapter deals with potential mega-engineering projects to regulate the climate directly. Most promising may be an adjustable sun-shade in space. Some engineering type has done the maths and figures it needs to be seven miles in diameter and could be stationed at one of the Lagrange points between the earth and the sun. Lovelock says this isn't a cure for Gaia, we still need to clean up our act, but it could buy us a few decades.

This set me to a bit of speculation of my own. From Lovelock's model, it is apparent that the earth system even without human meddling is getting near the end of it's life-span. The natural CO2 level is almost as low as it can go; the adjustment knob is almost all the way to the end.

So what if Gaia "knew" this and somehow threw up that so-called random mutation in the first place. If the old gal thought in human terms she might of seen the end coming and figured she needed some high-tech fix to keep the gig going. "I need me some clever monkeys who can build me a new thermostat."

Of course, Lovelock is always careful to say that Gaia acts "as if" it were a living entity. I don't have to be so careful.

LINKS - A brief article by Lovelock about his doomsday scenario
A semi-critical scientific analysis of Lovelock's work

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