Monday, May 18, 2009

Geoengineering and Scalability

I have colleagues who are volcanologists. Volcanoes dump a lot of sulfur into the stratosphere when they explode. My colleagues claim these explosions provide empirical confirmation for our climate models. And so they claim we can rely on these models to predict, including what would happen if we put sulfur dioxide into the stratosphere to decrease the amount of sunlight reaching the Earth. Rely on them how much? This seems to me like a crucial question. For otherwise, all we have to go on would be the results of experiments we might conduct at low rates of insertion from which might try to extrapolate to high rates of insertion. But extrapolate on what basis? Using what model? Volcanic explosion have the virtue of being really big. So they approach the scale of insertion we would need – but they are of short duration. Extrapolating to what would happen with insertion of long duration is what we seek. But here too we are faced with the same dilemma – on what basis? Using what model?

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