James Lovelock’s Gloomy Vision

At this point in the book, about half-way through, Lovelock diverts from the question of our impending doom into various other, much smaller issues like whether nitrates in food are really bad for you. It felt surreal, like the serving staff on the Titanic arguing about whether a time card had been properly punched or not. Lovelock uses this material to make the point that people worry about all the wrong stuff. OK, that’s a legitimate point, but I was left wishing for some discussion of what shape the catastrophe might take.

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.

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