How much would SPICE really damage the OZONE layer?

And how much of the Ozone layer would we really lose? This 2008 study suggests that it wouldn’t be the total destruction of the Ozone layer at all.

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.

Also, this study says suggests the whole field is still in its infancy:

Some areas of research remain unexplored. Although ozone may be depleted, with a consequent increase to solar ultraviolet-B (UVB) energy reaching the surface and a potential impact on health and biological populations, the aerosols will also scatter and attenuate this part of the energy spectrum, and this may compensate the UVB enhancement associated with ozone depletion. The aerosol will also change the ratio of diffuse to direct energy reaching the surface, and this may influence ecosystems. The impact of geoengineering on these components of the Earth system has not yet been studied. Representations for the formation, evolution and removal of aerosol and distribution of particle size are still very crude, and more work will be needed to gain confidence in our understanding of the deliberate production of this class of aerosols and their role in the climate system.

Indeed, the conclusions of this JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 113, D16101, doi:10.1029/2008JD010050, 2008, says on page 13 of their PDF

[31] Mitigation (reducing emissions of greenhouse gases) will reduce global warming, but is only now being seriously addressed by the planet. Whether we should use geoengineering as a temporary measure to avoid the most serious consequences of global warming requires a detailed evaluation of the benefits, costs, and dangers of different options. MacCracken [2006], Bengtsson [2006], Cicerone [2006], Kiehl [2006], and Lawrence [2006] all express concern about geoengineering. Robock [2008b] lists 20 reasons that argue against the implementation of this kind of geoengineering. The work here helps to document some benefits of geoengineering (global cooling and preservation of Arctic sea ice), but also the possible side effects on regional climate, item 1 on that list.

The side-effects of the decreased Ozone layer cannot be too bad, when one considers who is pushing the sulphur shield.

Professor Paul Crutzen, winner of the 1995 Nobel Prize for his work on the Antarctic ozone hole, has proposed an emergency geoengineering solution to cool off the planet: dump huge quantities of sulfur particles into the stratosphere to reflect sunlight. His paper, “Albedo Enhancement by Stratospheric Sulfur Injections: A Contribution to Resolve a Policy Dilemma?” was published in the August 2006 issue of the journal Climatic Change. A recent editorial in the New York Times by Ken Caldeira called for more research into geoengineering schemes like this to cool the planet, proposing that 1% of the $3 billion federal Climate Change Technology Program should be spent thusly.

If Paul Crutzen is advising the sulphur shield as an emergency stop-gap, then it cannot be too bad for the Ozone layer.

It’s an interesting area of study. For now we should seal this scheme behind a glass door that reads “Break only in case of emergency”. Sadly, with the world’s inaction on climate change and suspicion of nuclear power, it seems like we are rapidly approaching one!

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