Assessing Future Temperature and Precipitation Responses to Solar Radiation Management in Bangladesh: A Comparative Analysis with SSP Scenarios

Afifa Talukder, Mohammad Kamruzzaman, Syed Hafizur Rahman 

Bangladesh is among the most climate-vulnerable nations globally, facing compounding risks from rising temperatures, shifting precipitation patterns, and intensifying extreme events. This study assesses projected changes in precipitation, maximum temperature (Tmax), and minimum temperature (Tmin) over Bangladesh under two emission pathways — SSP2-4.5 and SSP5-8.5 — and two Solar Radiation Management (SRM) scenarios — G6Solar and G6Sulfur — using bias-corrected CMIP6 multi-model ensemble data for the period 2070–2099. Bias correction using the Quantile Delta Mapping method substantially improved model performance, with Nash-Sutcliffe Efficiency rising from −0.28 to 0.97 for precipitation and from −0.11 to 0.99 for temperature. Relative to the historical baseline (1985–2014), annual Tmax increases by 1.27°C under SSP2-4.5 and 2.36°C under SSP5-8.5, while Tmin increases by 1.71°C and 3.02°C, respectively. SRM scenarios substantially moderate warming, with Tmax increases of 1.33°C (G6Solar) and 1.45°C (G6Sulfur), and Tmin increases of 1.90°C (G6Solar) and 1.95°C (G6Sulfur). Warming is strongest in winter and weakest during the monsoon across all scenarios. Annual precipitation increases across all scenarios relative to historical levels, with the largest rise under SSP5-8.5; however, G6Solar produces 2.5% less precipitation than SSP2-4.5, raising concerns about seasonal drought risk, particularly during pre-monsoon and post-monsoon periods. Spatially, the southeastern and coastal regions experience the greatest increases in both temperature and precipitation, while northern Bangladesh shows comparatively smaller changes. Trend analysis using the Modified Mann-Kendall test reveals significant increasing temperature trends in all scenarios, strongest under SSP5-8.5 (Tmin: 0.47°C decade−1; Tmax: 0.38°C decade−1). The SRM scenarios partially offset high-emission warming but introduce precipitation uncertainties, underscoring that geoengineering should complement, not replace, greenhouse gas mitigation.