Regional climate impacts of stabilizing global warming at 1.5 K using solar geoengineering

This is the author accepted manuscript. The final version is available from Wiley via the DOI in this recordThe 2015 Paris Agreement aims to limit global warming to well below 2 K above pre-industrial levels, and to pursue efforts to limit global warming to 1.5 K, in order to avert dangerous climate change. However, current greenhouse gas emissions targets are more compatible with scenarios exhibiting end-of-century global warming of 2.6 - 3.1 K, in clear contradiction to the 1.5 K target. In this study, we use a global climate model to investigate the climatic impacts of using solar geoengineering by stratospheric aerosol injection to stabilize global-mean temperature at 1.5 K for the duration of the 21st century against 3 scenarios spanning the range of plausible greenhouse gas mitigation pathways (RCP2.6, RCP4.5, RCP8.5). In addition to stabilizing global mean temperature and offsetting both Arctic sea-ice loss and thermosteric sea-level rise, we find that solar geoengineering could effectively counteract enhancements to the frequency of extreme storms in the North Atlantic and heatwaves in Europe, but would be less effective at counteracting hydrological changes in the Amazon basin and North Atlantic storm track displacement. In summary, solar geoengineering may reduce global mean impacts but is an imperfect solution at the regional level, where the effects of climate change are experienced. Our results should galvanize research into the regionality of climate responses to solar geoengineering.CJ is supported by the Natural Environmental Research Council via the CLoud-Aerosol-Radiation Interactions and Forcing: Year 2016 (CLARIFY-2016) project (CLARIFY, NE/L013797/1). MKH and JMH were supported by the Natural Environment Research Council/Department for International Development via the Future Climates for Africa (FCFA) funded project ’Improving Model Processes for African Climate’ (IMPALA, NE/M017265/1). JMH and AJ were supported by the Joint UK BEIS/Defra Met Office Hadley Centre Climate Programme (GA01101). XG and JM were supported by the National Basic Research Program of China (Grant 2015CB953600)