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Identifying climate impacts from different Stratospheric Aerosol Injection strategies in UKESM1
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  • Alice Florence Wells,
  • Matthew Henry,
  • Ewa M. Bednarz,
  • Douglas G MacMartin,
  • Andy Jones,
  • Mohit Dalvi,
  • Jim M. Haywood
Alice Florence Wells
Exeter University

Corresponding Author:[email protected]

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Matthew Henry
University of Exeter
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Ewa M. Bednarz
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Douglas G MacMartin
Cornell University
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Andy Jones
Met Office
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Mohit Dalvi
Met Office
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Jim M. Haywood
Met Office
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Stratospheric Aerosol Injection (SAI) is a proposed method of climate intervention aiming to reduce the impacts of human-induced global warming by reflecting a portion of incoming solar radiation. Many studies have demonstrated that SAI would successfully reduce global-mean surface air temperatures, however the vast array of potential scenarios and strategies for deployment result in a diverse range of climate impacts. Here we compare two SAI strategies - a quasi- equatorial injection and a multi-latitude off-equatorial injection - simulated with the UK Earth System Model (UKESM1), both aiming to reduce the global-mean surface temperature from that of a high-end emissions scenario to that of a moderate emissions scenario. Both strategies effectively reduce global mean surface air temperatures by around 3°C by the end of the century; however, there are significant differences in the resulting regional temperature and precipitation patterns. We compare changes in the surface and stratospheric climate under each strategy to determine how the climate response depends on the injection location. In agreement with previous studies, an equatorial injection results in a tropospheric overcooling in the tropics and a residual warming in the polar regions, with substantial changes to stratospheric temperatures, water vapour and circulation. However, we demonstrate that by utilising a feedback controller in an off-equatorial injection strategy, regional surface temperature and precipitation changes relative to the target can be minimised. We conclude that moving the injection away from the equator minimises unfavourable changes to the climate, calling for a new series of inter-model SAI comparisons using an off-equatorial strategy.
14 Dec 2023Submitted to ESS Open Archive
27 Dec 2023Published in ESS Open Archive