Afro-Asian Climate Response to Future Solar Radiation Management

[Geoengineering News]

https://www.sciencedirect.com/science/article/pii/S2210670725006985

Authors: Tolulope E. Adeliyi, Akintomide A. Akinsanola, Thierry N. Taguela

https://doi.org/10.1016/j.scs.2025.106825

16 September 2025

Highlights

•SRM reduces JJAS temperatures by up to 3°C across monsoon regions.

•Heatwave frequency, duration, and intensity reduce significantly with SRM.

•SRM-induced cooling is driven by reduced net downward radiation.

•Population exposure to heatwaves is reduced, especially in the far-future.

Abstract

Rising global temperatures due to greenhouse gas emissions are increasingly exposing billions across the densely populated Afro-Asian monsoon regions to extreme heat stress. This study assesses the potential of solar radiation management (SRM), using stratospheric aerosol injection (G6Sulfur) and solar radiation dimming (G6Solar), to mitigate future changes in temperature and heatwave characteristics during the boreal summer monsoon season (June to September) over the mid-future (2040-2069) and far-future (2070-2099), based on simulations from the Geoengineering Model Intercomparison Project (GeoMIP) under CMIP6. Compared to the high-emission SSP5-8.5 scenario, both G6Solar and G6Sulfur substantially reduce projected increases in mean, maximum, and minimum temperatures across the South Asian, East Asian, and West African monsoon regions, with cooling exceeding 3°C in some areas by the far-future. The frequency, duration, and intensity of all heatwave characteristics are also significantly reduced, by over 20 days, 10 days, and 1.0°C, respectively. Surface energy budget diagnostics reveal that the temperature reduction is driven primarily by reduced net downward surface radiation, largely due to decreased clear-sky downward longwave radiation associated with reduced atmospheric water vapor. Moisture budget diagnostics further show that reduced atmospheric water vapor convergence is modulated by decreased thermodynamic processes, particularly specific humidity. Finally, both SRM methods lead to substantial reductions in population exposure to all heatwave types, especially in the far-future. These findings suggest that SRM could help alleviate future heat-related health risks and reduce pressure on urban infrastructure across the Afro-Asian monsoon regions.

Source: ScienceDirect