Impacts of climate change and solar geoengineering on the local climate of a megacity: A case study of Buenos Aires, Argentina

Buenos Aires, Argentina, is one of the world’s megacities. The metropolitan area of Buenos Aires extends for around 4000 km2 and has 14 million inhabitants. As climate change intensifies, local existing social and environmental challenges exacerbate the need for an updated portfolio that considers all climate change strategies, including solar geoengineering or Solar Radiation Modification (SRM), which consists of ideas aimed at slowing or halting global warming by reflecting a small portion of sunlight away from the Earth. This study explores the potential risks and benefits that SRM in the form of stratospheric aerosol injection (SAI) would bring to the urban climate of Buenos Aires in comparison with the risks and benefits of ongoing and projected local climate change. This solar geoengineering technique introduces changes in atmospheric conditions that are quantified and evaluated at the urban scale through the bias correction and statistical downscaling (BC) of the ARISE-SAI-1.5 climate simulations designed to be policy relevant as they aim to maintain global surface temperatures at ∼1.5°C above pre-industrial levels. We evaluate the potential impacts of SAI at local scale compared to the impacts under the intermediate SSP2–4.5 scenario. Quantitative information on changes in daily mean and extreme precipitation and temperature for Buenos Aires under SAI and the SSP2–4.5 scenarios were computed for different future time slices. Results indicate that the avoided warming for Buenos Aires varies based on the BC method used when comparing the SAI and non-SAI scenarios. For the period 2035-2049, the maximum and minimum temperature reductions range from 0.3°C to 0.4°C. In 2055-2069, the reduction in temperature increases to between 1.3°C and 1.4°C. Additionally, the non-SAI scenario is projected to be wetter than the SAI scenario, with increases in rainfall of 1.1% to 1.7% for 2035-2049 and 3.8% to 5.4% for 2055-2069.