THE GLOBAL IMPACTS OF POLAR GEOENGINEERING

The Arctic is warming two to four times faster than the global average (Jacobs et al., 2021), (Masson-Delmotte et al., 2021), and has lost three quarters of its late summer sea ice volume in 40 years (Notz & Stroeve, 2018). The sea-ice albedo feedback and release of greenhouse gases from thawing permafrost mean these changes add to the burden of global warming, and the loss of polar ice sheets is the largest contributor to long-term sea level rise. Solar geoengineering describes a set of proposals to cool the Earth by reflecting away sunlight. While most research has focused on global applications, the Arctic is an obvious regional target. In this project I will assess the potential for solar geoengineering to arrest Arctic changes, especially sea-ice loss, and the implications of such interventions for the global climate, in particular on mid-latitude weather extremes and the modes of variability that drive them. The Met Office's Hadley Centre climate models will be used to simulate the effects of stratospheric aerosol geoengineering, marine cloud brightening, and sea-ice albedo modification. These simulations will then be compared with observations and simulations of the climate response to historical volcanic eruptions, a natural analogue for geoengineering.