Carbon-negative volcanism
April 18, 2010, 8:57 pm
Filed under: Uncategorized

The excellent Michael Tobis points to this infographic from Information is Beautiful which compares the CO2 emitted by Eyjafjallajokull to the amount of carbon not being emitted by the planes now grounded in Europe, and asks if this is the first carbon-negative eruption.

The answer is surely no: other volcanoes have done much more on the carbon front. There’s a fairly clear flattening in the Keeling Curve in the early 1990s which is equivalent to about 2 gigatonnes of carbon missing. It’s associated with Pinatubo temporally, and there are two separate global mechanisms with which to explain it. The first is that it because Pinatubo reduced the temperature it reduced soil respiration, a major source of CO2. The second is that plants like diffuse light, and the stratospheric sulphate veil produced by Pinatubo provided it. As a result the plants sucked down more CO2 while the bugs beneath them were  producing less.

The importance of the two different effects is debated. The diffuse light effect is now widely accepted as real, but how much of the Pinatubo effect it accounts for is not fully agreed. It’s also a little hard to get rid of the effects of the El Nino happening at the same time (there are a lot of climate scientists who would really like a Pinatubo without an El Nino in order to isolate the influence of the volcano). Here’s a very good post by Tamino that lays the arguments out.

Either way, Pinatubo is a big time carbon-negative winner.

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