https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2024EF004422
*Authors* Jun Wang, Liyun Zhao, John C. Moore *First published*: *15 July 2024* https://doi.org/10.1029/2024EF004422 *Abstract* Beijing is undergoing multiple challenges including urbanization, warming and aging. The Beijing megalopolis of 20 million people now suffers more cold-related than heat-related deaths. Stratospheric aerosol injection (SAI) geoengineering is designed to lower surface temperatures, so if SAI were ever done, it may reduce future heat-related mortality, while also increasing cold-related mortality. Here we use four Earth System Models (ESM) downscaled to 10 km resolution with the Weather Research and Forecasting (WRF) system to capture urban temperature, humidity and wind speeds. Temperature-related mortality risk were calculated using a distributed lag nonlinear model (DLNM) of the elderly (over 65s) under the dynamically downscaled moderate (RCP4.5) and extreme (RCP8.5) greenhouse gas, and the G4 SAI scenarios. We used population demographics for all five shared socioeconomic pathways (SSP) and various adaptation measures. Heat-related excess deaths under G4 are 630∼3,160 per year fewer than RCP4.5, while cold-related deaths are 370∼1,990 more than RCP4.5 during 2060–2069, with a marginally significant net reduction. G4 significantly reduces the excess deaths relative to RCP8.5. Both heat-related and cold-related mortality will increase by 240∼490% when the aging population is accounted for, and decrease by 11%, 23% and 44% under low, medium and high adaptation relative to a no adaptation scenario. Dynamical downscaling produces better quality climate simulations than commonly used statistical approaches, and in the case of Beijing, significantly fewer heat-related deaths. The marginal health benefits of modest future SAI in Beijing may be representative of the population impacts in the extra-tropics where deaths due to cold are more than those caused by heat. *Key Points* Stratospheric aerosol injection (SAI) geoengineering on both heat-related and cold-related mortality for the elderly in Beijing was simulated GeoMIP G4 SAI reduces heat-related excess deaths, but also increases cold-related excess deaths, with little net negative differences from RCP4.5 Dynamical downscaling significantly reduces projecting future heat-related excess deaths relative to statistical methods *Plain Language Summary* Climate warming has increased the intensity and frequency of extreme weather has consequences for human health in the 21st century. Stratospheric aerosol injection (SAI) geoengineering can, to some extent, slow down global warming, but its impact on human health is unclear. Beijing is one of the most populous and developed cities in China and is undergoing dual challenges of warming and aging which amplify the health risks to the elderly population. It is therefore of both local significance and wider relevance for developing world cities to explore the impact of SAI geoengineering on the mortality of elderly people in Beijing. We project heat-related and cold-related excess deaths under different climate, population and adaptation scenarios in Beijing during the 2060s. SAI geoengineering could reduce approximately 630∼3,160 heat-related excess deaths, but it could also increase 370∼1,990 cold-related excess deaths. There are large uncertainties in projection of excess deaths under different shared socioeconomic pathways. *Source: AGU* -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/geoengineering/CAHJsh98Y33HM5LQes0813WZgqhn0vyXxtx_8gSY42117tnf_nQ%40mail.gmail.com.
