How Close to Catastrophe?

[This piece, which appears in the November 16, 2006 issue of the New York Review of Books, is posted here with the kind permission of the editors of that magazine.]

James Lovelock is among the planet's most interesting and productive scientists. His invention of an electron capture device that was able to detect tiny amounts of chemicals enabled other scientists both to understand the dangers of DDT to the eggshells of birds and to figure out the ways in which chlorofluorocarbons (CFCs) were eroding the ozone layer. He's best known, though, not for a gadget but for a metaphor: the idea that the earth might usefully be considered as a single organism (for which he used the name of the Greek earth goddess Gaia) struggling to keep itself stable

In fact, his so-called Gaia hypothesis was at first less clear than that -- "hardly anyone, and that included me for the first ten years after the concept was born, seems to know what Gaia is," he has written. But the hypothesis has turned into a theory, still not fully accepted by other scientists but not scorned either. It holds that the earth is "a self-regulating system made up from the totality of organisms, the surface rocks, the ocean and the atmosphere tightly coupled as an evolving system" and striving to "regulate surface conditions so as always to be as favourable as possible for contemporary life."

Putting aside questions of planetary consciousness and will (beloved as they were by an early wave of New Age Gaia acolytes), the theory may help us understand how the earth has managed to remain hospitable for life over billions of years even as the sun, because of its own stellar evolution, has become significantly hotter. Through a series of processes involving, among others, ice ages, ocean algae, and weathering rock, the earth has managed to keep the amount of heat-trapping carbon dioxide in the atmosphere, and hence the temperature, at a relatively stable level.

This homeostasis is now being disrupted by our brief binge of fossil fuel consumption, which has released a huge amount of carbon dioxide into the atmosphere. Indeed, at one point Lovelock predicts -- more gloomily than any other competent observer I am aware of -- that we have already pushed the planet over the brink, and that we will soon see remarkably rapid rises in temperature, well beyond those envisioned in most of the computer models now in use – themselves quite dire. He argues that because the earth is already struggling to keep itself cool, our extra increment of heat is particularly dangerous, and he predicts that we will soon see the confluence of several phenomena: the death of ocean algae in ever-warmer ocean waters, reducing the rate at which these small plants can remove carbon from the atmosphere; the death of tropical forests as a result of higher temperatures and the higher rates of evaporation they cause; sharp changes in the earth's "albedo," or reflectivity, as white ice that reflects sunlight back out into space is replaced with the absorptive blue of seawater or the dark green of high-latitude boreal forests; and the release of large amounts of methane, itself a greenhouse gas, held in ice crystals in the frozen north or beneath the sea.

Some or all of these processes will be enough, Lovelock estimates, to tip the earth into a catastrophically hotter state, perhaps eight degrees centigrade warmer in temperate regions like ours, over the course of a very few decades, and that heat will in turn make life as we know it nearly impossible in many places. Indeed, in the photo section of the book there is one picture of a red desert captioned simply "Mars now -- and what the earth will look like eventually." Human beings, a hardy species, will not perish entirely, he says; in interviews during his book tour, Lovelock has predicted that about 200 million people, or about one thirtieth of the current world population, will survive if competent leaders make a new home for us near the present-day Arctic. There may also be other survivable spots, like the British Isles, though he notes that rising sea levels will render them more an archipelago. In any event, he predicts that "teeming billions" will perish.