A Physicist on Climate Change

Here are some bits from an essay on climate change in The American Scholar by Nobel prize-winning physicist Robert B. Laughlin.

Common sense tells us that damaging a thing this old is somewhat easier to imagine than it is to accomplish—like invading Russia. The earth has suffered mass volcanic explosions, floods, meteor impacts, mountain formation, and all manner of other abuses greater than anything people could inflict, and it’s still here. It’s a survivor. We don’t know exactly how the earth recovered from these devastations, because the rocks don’t say very much about that, but we do know that it did recover—the proof of it being that we are here.

Nonetheless, damaging the earth is precisely what’s concerning a lot of responsible people at the moment. Carbon dioxide from the human burning of fossil fuel is building up in the atmosphere at a frightening pace, enough to double the present concentration in a century. This buildup has the potential to raise average temperatures on the earth several degrees centigrade, enough to modify the weather and accelerate melting of the polar ice sheets. Governments around the world have become so alarmed at this prospect that they’ve taken significant, although ineffective, steps to slow the warming. These actions include legislating carbon caps, funding carbon sequestration research, subsidizing alternate energy technologies, and initiating at least one serious international treaty process to balance the necessary economic sacrifices across borders.

Unfortunately, this concern isn’t reciprocated. On the scales of time relevant to itself, the earth doesn’t care about any of these governments or their legislation. It doesn’t care whether you turn off your air conditioner, refrigerator, and television set. It doesn’t notice when you turn down your thermostat and drive a hybrid car. These actions simply spread the pain over a few centuries, the bat of an eyelash as far as the earth is concerned, and leave the end result exactly the same: all the fossil fuel that used to be in the ground is now in the air, and none is left to burn. The earth plans to dissolve the bulk of this carbon dioxide into its oceans in about a millennium, leaving the concentration in the atmosphere slightly higher than today’s. Over tens of millennia after that, or perhaps hundreds, it will then slowly transfer the excess carbon dioxide into its rocks, eventually returning levels in the sea and air to what they were before humans arrived on the scene. The process will take an eternity from the human perspective, but it will be only a brief instant of geologic time.

Some details of this particular carbon dioxide scenario are controversial, of course, since all forecasts are partly subjective, including those made by computer. You have to extrapolate from present-day facts and principles, and there are varying opinions about these. The time scale for man-made carbon dioxide to be absorbed by the ocean is set by the mixing rate of surface water with deep water in the sea, which is known only indirectly and might conceivably change during the thousand-year hot spell. The amount of carbon dioxide left in the atmosphere after equilibration varies from tolerable to alarming depending on how much industrial burning the model assumes. No one knows for sure how long it will take the excess carbon dioxide to turn into limestone and disappear into the rocks, or even the specific chemistry involved. The main reason for thinking it will disappear is that something, presumably a geologic regulatory process, fixed the world’s carbon dioxide levels before humans arrived on the scene. Some people argue that carbon dioxide has been locked to these values for millions of years, the grounds of the argument being that the photosynthetic machinery of plants seems optimized to them. But the overall picture of a thousand-year carbon dioxide pulse followed by glacially slow decay back to the precivilization situation is common to most models, even very pessimistic ones.

Global warming forecasts have the further difficulty that you can’t find much actual global warming in present-day weather observations. In principle, changes in climate should show up in rainfall statistics, hurricane frequency, temperature records, and so forth. As a practical matter they don’t, because weather patterns are dominated by large multi-year events in the oceans, such as the El Niño Southern Oscillation and the North Pacific Gyre Oscillation, which have nothing to do with climate change. In order to test the predictions, you’d have to separate these big effects from subtle, inexorable changes on scales of centuries, and nobody knows how to do that yet.

Humans can unquestionably do damage persisting for geologic time if you count their contribution to biodiversity loss. A considerable amount of evidence shows that humans are causing what biologists call the “sixth mass extinction,” an allusion to the five previous cases in the fossil record where huge numbers of species died out mysteriously in a flash of geologic time. A popular, and plausible, explanation for the last of these events, the one when the dinosaurs disappeared, is that an asteroid 10 kilometers in diameter, traveling 15 kilometers per second, struck the earth and exploded with the power of a million 100-megaton hydrogen warheads. The damage that human activity presently inflicts, many say, is comparable to this. Extinctions, unlike carbon dioxide excesses, are permanent. The earth didn’t replace the dinosaurs after they died, notwithstanding the improved weather conditions and 20,000 ages of Moses to make repairs. It just moved on and became something different than it had been before.

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The geologic record as we know it thus suggests that climate is a profoundly grander thing than energy. Energy procurement is a matter of engineering and keeping the lights on under circumstances that are likely to get more difficult as time progresses. Climate change, by contrast, is a matter of geologic time, something that the earth routinely does on its own without asking anyone’s permission or explaining itself. The earth doesn’t include the potentially catastrophic effects on civilization in its planning. Far from being responsible for damaging the earth’s climate, civilization might not be able to forestall any of these terrible changes once the earth has decided to make them. Were the earth determined to freeze Canada again, for example, it’s difficult to imagine doing anything except selling your real estate in Canada. If it decides to melt Greenland, it might be best to unload your property in Bangladesh. The geologic record suggests that climate ought not to concern us too much when we’re gazing into the energy future, not because it’s unimportant, but because it’s beyond our power to control.

Go read the whole article. It is a profoundly sensible presentation of facts and the limits of our current science. Laughlin is a good antidote to a lot of hysteria that is over-hyped by the catastrophist crowd.