Summary
This research examines how strategies for Solar Radiation Modification (SRM) affect water flow in the tropical Kelantan River Basin (KRB) in Malaysia. Using climate models, the study confirms that SRM methods effectively limit temperature increases, keeping warming much closer to moderate emission goals than to the severe SSP5-8.5 scenario. However, the findings highlight risks to the hydrological cycle: Increased monthly precipitation from November to January is projected to intensify flood risks in the mid-21st century. The G6sulfur SRM scenario is specifically projected to decrease streamflow during dry months in the middle and upper basin, potentially making existing water shortages worse.
Abstract
Solar radiation modification (SRM) is a potential strategy to rapidly mitigate global warming by reflecting more sunlight into space. However, its impact on tropical hydrological cycles remains underexplored. This study investigates the potential effects of SRM on streamflow in the Kelantan River Basin (KRB) by incorporating climate projections from the Geoengineering Model Intercomparison Project Phase 6 (GeoMIP6) into the Soil and Water Assessment Tool plus (SWAT+) model. Results indicate that UKESM1-0-LL and MPI-ESM1-2-LR exhibit higher uncertainty in representing KRB’s climate compared to CNRM-ESM2-1 and IPSL-CM6A-LR. Under SSP5-8.5, maximum and minimum temperatures are projected to increase by up to 3.52 °C by the late 21st century, while SRM scenarios may limit warming to 1.72-2.33 °C, similar to 1.96-2.22 °C under SSP2-4.5. The multi-model ensemble mean projected an inverse V-shaped trend in annual precipitation, with a peak in the mid-21st century before declining, except for G6sulfur, which exhibits a steady decrease. Increases in monthly precipitation from November to January during the 2045-2064 period under all evaluated scenarios may intensify flooding in the KRB. Meanwhile, decreases in streamflow during dry months are projected for the periods 2045-2064 and 2065-2085 under G6sulfur, particularly in the middle and upper basins
