A note on stratospheric aerosols, the cryosphere and future climate change....

Stratospheric sulfate aerosols, the cryosphere and climate change …

Recently in my search for literature on stratospheric sulfate aerosols, I came across a few pieces on stratospheric aerosols and the cryosphere and as a recent lecture highlighted the importance of the cryosphere and the seriousness of the changes that are taking place within it I thought I would include a post about the viability of stratospheric aerosol injections in alleviating the loss of ice and sea level rise.

Changes in the crysophere such as the loss of Arctic sea ice and the Greenland and Antarctic ice sheets in recent years have been more rapid than expected. Global warming effects are projected to be the largest in the polar regions, however, it is these regions where climatic responses to warming are most uncertain. The potential impacts of further changes have consequently raised the question of whether geo-engineering, or more specifically, stratospheric sulfate aerosols, can be used to alleviate the loss of ice and sea level rise.

Using the Community Climate System Model version 3, Bitz et al., (2010) imposed stratospheric sulfate aerosol loadings in a series of integrations with the model and found that aerosols can counter ‘many effects of greenhouse warming’ however perfect cancellation is not possible. Rather, when aerosols roughly cancel global average warming, temperature changes in the polar regions are still 20-50% of the changes in the warmed world (McCusker et al., 2011). The aerosols cause a southerly migration of the southern hemisphere jet (McCusker et al., 2011) and these atmospheric circulation changes cause the over-cooling in Arctic summers and residual warming during Arctic winters (McCusker et al., 2010).

The conclusion that arises is that aerosol geo-engineering can serve to counter some of the climate impacts of stratospheric ozone recovery and rising CO2 but not all. Having said that, projected responses to geo-engineering in polar regions have high levels of uncertainty due to the high levels of uncertainty that are present in projections for the polar regions in general. Consequently, the question of whether we can avoid polar climate emergencies is not certain. More robust depictions of a climate that has been geo-engineered are thus needed – a conclusion of more research being needed is yet again the case.