Science has published a major new study, “The Sensitivity of Polar Ozone Depletion to Proposed Geoengineering Schemes” ($ub. req’d). The study finds:
The large burden of sulfate aerosols injected into the stratosphere by the eruption of Mount Pinatubo in 1991 cooled Earth and enhanced the destruction of polar ozone in the subsequent few years. The continuous injection of sulfur into the stratosphere has been suggested as a “geoengineering” scheme to counteract global warming. We use an empirical relationship between ozone depletion and chlorine activation to estimate how this approach might influence polar ozone. An injection of sulfur large enough to compensate for surface warming caused by the doubling of atmospheric CO2 would strongly increase the extent of Arctic ozone depletion during the present century for cold winters and would cause a considerable delay, between 30 and 70 years, in the expected recovery of the Antarctic ozone hole.
Pumping sulphur particles into the atmosphere to mimic the cooling effect of a large volcanic eruption has been proposed as a last-ditch solution to combating climate change — but doing so would cause problems of its own, including potentially catastrophic drought, say researchers.
And if we pursued the sulphur strategy but then found out, say, a decade later, the drought prediction was correct, we’d be stuck, since if we discontinued injecting the sulphur shield, global temperatures would rebound rapidly, potentially triggering catastrophic effects. (And, of course, this shield does nothing to stop catastrophic ocean acidification.)