reality has a well known depressing bent just now.

Via the BBC, I noticed this article in Nature Geoscience by Zeebe & Caldeira.

They’ve absolutely nailed down a carbon cycle some mouthbreathers were hoping didn’t explain much. Volcanoes spew vast quantities of greenhouse gases into the air, so their thinking — the mouthbreathers’ thinking, not the volcanoes — was that greenhouse gases are natural and couldn’t possibly be a problem. Mother Nature would take care of everything. Thus it ever was. Thus it ever shall be. (No, I’m not being fair to the scientists, as opposed to the politicians, who held the contrarian point of view. It’s way more complicated than that. But it’s still just as wrong.)

The evidence pointed toward a cycle in which the atmospheric carbon is eventually fixated into rocks. Corals, for instance, fix CO2 when they form calcium carbonate which makes limestone. Sedimentary rocks trap carbonates as they pile up. (That’s what the BBC means when they write that carbon is “removed from the air by rock weathering,” which, as written, doesn’t make any sense.) Then, by the processes of tectonic movement, the rock containing all that carbon moves toward subduction zones and is eventually forced down under the crust. The volatiles in those rocks, including some containing carbon, rise and force their way up through the volcanoes that run with the subduction zones.

If you’re sitting there thinking, “But, my God, that’s got to take nonillions of years!” that’s exactly the point. It takes over a hundred million years for the whole cycle, and during all that time the carbon is not in the atmosphere and not greenhousing.

So far, so good. We’ve known about this (well, some of us have known about this) for decades. The shocking thing to me about their research was the data on how much long term variation in atmospheric carbon there has been. This is data from ice cores. This is not a guess, or a pessimistic estimate, or a liberal fantasy to make the Republicans look bad. This is data.

The mean long term variation in atmospheric carbon has been 22 parts per million. Individual measurements have varied more than that, but overall, for the last 610,000 years, that’s been the variation.

Except for the last 200 years. We’ve already upped the concentration by 100 ppm. We’re going to increase it by another couple of hundred before we have any chance of stopping it. The big argument is whether we need to bother stopping it then, or whether another few hundred on top of that will really make any difference. Why ding the GDP a percentage point or two when there’s no need?

The mind boggles.

Twenty two parts per million has been the extent of the real variation for longer than modern humans have existed. But some of us can’t figure out that shoveling on way, way more than that will have any impact.

I hereby rename our species Homo stupidens.

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