Tropical hydro-climatic responses to global warming and solar radiation modification in the Kelantan River Basin, Malaysia

ABSTRACT

Solar radiation modification (SRM) has been discussed as 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 impacts of SRM on streamflow of 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. The findings reveal that UKESM1-0-LL and MPI-ESM1-2-LR exhibit greater uncertainty in representing the climate of the KRB compared to CNRM-ESM2-1 and IPSL-CM6A-LR. Maximum and minimum temperatures under SSP5-8.5 are projected to increase by up to 3.52 °C by the end of the 21st century, while these increases could be limited to between 1.72 and 2.33 °C under SRM scenarios, corresponding to 1.96 to 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 during the 2045–2064 period 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.