Reduced Poleward Transport Due to Stratospheric Heating Under
Stratospheric Aerosols Geoengineering
Abstract
By injecting SO2 into the stratosphere at four latitudes (30°, 15° N/S),
it might be possible not only to reduce global mean surface temperature
but also to minimize changes in the equator-to-pole and
inter-hemispheric gradients of temperature, further reducing some of the
impacts arising from climate change relative to equatorial injection.
This can happen only if the aerosols are transported to higher latitudes
by the stratospheric circulation, ensuring that a greater part of the
solar radiation is reflected back to space at higher latitudes,
compensating for the reduced sunlight. However, the stratospheric
heating produced by these aerosols modifies the circulation and
strengthens the stratospheric polar vortex which acts as a barrier to
the transport of air toward the poles. We show how the heating results
in a feedback where increasing injection rates lead to stronger
high-latitudinal transport barriers. This implies a potential limitation
in the high-latitude aerosol burden and subsequent cooling.