Real Climate, a commentary website on climate science by working climate scientists for the interested public, has commented on James Lovelock‘s new book Revenge of Gaia: Why the earth is fighting back – and how we can still save humanity.
Lovelock recently wrote a melodramatic article in the Independent, The Earth is about to catch a morbid fever that may last as long as 100,000 years, based upon his book.
This article is the most difficult I have written and for the same reasons. My Gaia theory sees the Earth behaving as if it were alive, and clearly anything alive can enjoy good health, or suffer disease. Gaia has made me a planetary physician and I take my profession seriously, and now I, too, have to bring bad news.
Our planet has kept itself healthy and fit for life, just like an animal does, for most of the more than three billion years of its existence. It was ill luck that we started polluting at a time when the sun is too hot for comfort. We have given Gaia a fever and soon her condition will worsen to a state like a coma. She has been there before and recovered, but it took more than 100,000 years. We are responsible and will suffer the consequences: as the century progresses, the temperature will rise 8 degrees centigrade in temperate regions and 5 degrees in the tropics.
We are in a fool’s climate, accidentally kept cool by smoke, and before this century is over billions of us will die and the few breeding pairs of people that survive will be in the Arctic where the climate remains tolerable.
The Real Climate post by David Archer comments on the entire book:
The argument for approaching doom is made by analogy. (Again I feel compelled to editorialize. Argument by analogy is a powerful rhetorical tool, at which Lovelock is a master. Reasoning by analogy however is not a reliable divining rod for scientific discovery. “As above, so below” was a central tenet of the alchemists. We don’t do that anymore.) The analogy is to the failure of natural regulation of a human body, requiring artificial intervention. If the kidneys fail, a doctor has to take over regulation of blood chemistry using dialysis. If the pancreas fails, the patient requires manual regulation of sugar metabolism by insulin injection. It is generally bad news when the doctor tells you that your body’s natural regulation mechanisms are failing, because artificial, technological fixes are typically not as reliable as the natural ones. There is no doubt that mankind is taking over the reins of global geochemical balance. Industrial production of fixed nitrogen for fertilizer now matches the natural rate of nitrogen fixation on the planet. Rates of fossil-fuel CO2 emission dwarf the natural rate of CO2 release in volcanic gases. Lovelock’s conclusion, by analogy, is that the biosphere of the Earth will soon be beset by all manner of unanticipated complications.
This does not seem to me an unreasonable conclusion, I must admit. Consider Biosphere II. This was a sealed greenhouse in the Arizona desert, an attempt to create a managed, self-contained biosphere. A very humbling effort it turned out to be, all in all. Biological control proved to be completely out of reach. Several species of birds were introduced into the system, based on rational design of ecological balance, and all of them went extinct. The only birds that flourished in BII were a local species that invaded the structure while it was under construction that they never managed to eradicate. Ants and cockroaches became so abundant in BII that the biospherians took to sucking them up into vacuum cleaners and feeding them to their domesticated chickens. Geochemically, the oxygen concentration plummeted and nitrous oxide rose, until the structure became uninhabitable.
Based on the experiences of the Biospherians, I would imagine that the wildest instabilities might be biological. We can cope with bacteria, at least better than humankind could back in the days of the Black Death in Europe, but bacteria are adept at evolving defenses to our chemical weapons, and viruses are much more difficult to attack. A new plague would spread globally, much faster than it did in the middle ages. A biological collapse might be attributable to human overpopulation, or monoculture agriculture, perhaps more so than to climate change.
Geochemically, I could imagine the chemistry of the atmosphere shifting to a new equilibrium, in which (say) carbon monoxide could suddenly rise up to harmful levels. The oxidation chemistry of the atmosphere has been altered in all different directions by human emissions of organic compounds, nitrogen compounds, and methane. No one understands why the lifetime of methane in the atmosphere is as stable as it appears to been over the past decades. Surprises could lurk here.
Methane hydrates seem dangerous, because there is so much methane. If all of the hydrates were to melt within a few years, we would have a methane spike in the atmosphere that would be catastrophic, because methane is such a powerful greenhouse gas. But it seems more likely that the hydrates would melt slowly, over centuries and millennia. If that is the case, the climate impact might be comparable to fossil fuel CO2 combustion. It could double the human climate impact, but probably not make it 10 times worse or anything like that.
Physically, there have been abrupt climate changes in the past, which we are just beginning to figure out. Transitions between stable climate states may be sudden. Some transitions are driven by sharp changes in physical properties of substances like water. There is a sharp boundary between a stable and a runaway greenhouse effect, because of the sharp phase boundary between water vapor and liquid. Abrupt climate changes in the glacial North Atlantic may have been amplified by freezing of sea ice. Dynamical systems may also change states quickly. Ocean circulation seems to have multiple configurations, also apparently generating abrupt glacial North Atlantic climate changes. The dynamical balance in hurricanes on earth is between latent heat and wind friction with the ground, but if the pressure dropped low enough, ground friction fails as a regulator and a new beast, called a “hypercane”, could arise [Emanuel et al., 1995]. No one is suggesting that hypercanes will arise on Earth, but this is an example of a sharp transition in a dynamical system. It would be extremely difficult to forecast abrupt climate changes such as this for the future.
The Earth has existed in hot-house configuration before, and contrary to Lovelock’s vision, I don’t know of anything intrinsic to the hot-house Earth which would preclude human life. The transition from present-day climate to a radically new climate could be catastrophic from the point of view of human civilization however, especially given that Earth is loaded with so many people already. Past climate transitions often drove extinctions and eventually new speciation. Past societies, such as the Classic Mayans, apparently vanished from the face of the earth, leaving behind mute relics of past social structure. These societal collapses were regional, often triggered by regional climate changes. The world today is globalized to an extent that was never a factor in the past, and climate is poised to change in a global way such as civilized humanity has not before witnessed.
We should be very clear. No one, not Lovelock or anyone else, has proposed a specific, quantitative scenario for a climate-driven, all out, blow the doors off, civilization ending catastrophe. Mr. Lovelock has a feeling in his gut that something terrible is going to happen. He could be right, but for what it’s worth, there aren’t any models that explode as catastrophically as this. We can never say that it’s impossible that something might fall out of balance, something we haven’t thought of. But I think in general the consensus gut feeling among small-minded working scientists like me is that the odds of such a catastrophe are low.
Low odds of catastrophe does not imply negligible. Nordhaus  considered the possibility of catastrophe in his analysis of the economics of climate change. He defined catastrophe as comparable to the Great Depression, a 25% decrease in global economic activity that lasts for a long time. The probability of such an event he estimated by polling the gut instincts of a group of climate scientists; for what it’s worth, they came up with probabilities of a few percent. Economically, Nordhaus found that this possibility imposed the largest cost of adapting to climate change, greater than the costs of sea level rise, potential change in storminess, and so on. My own belief is that economics is a flawed tool for managing global climate, because it neglects issues of fairness, and reduces the value of the natural world to units of money. The point is that, within this framework, a small possibility of a large catastrophe looms large as a practical issue.