Wetland Loss Intensifies Regional Heat and Stress: Insights from the 2023 Southeast Asia Heatwave

Wetlands play a crucial role in regulating regional climate through their effects on surface energy balance and evapotranspiration. However, rapid wetland loss in Southeast Asia has raised concerns about its potential to intensify extreme weather events such as heatwaves. This study investigates the impact of wetland loss on regional temperature and human heat stress during the 2023 heatwave in the Cambodia Lower Mekong Delta (CLMD). Using the WRF model coupled with the Noah-MP land surface scheme, we conducted high-resolution ensemble simulations under three land cover scenarios: baseline, historical wetland extent, and current wetland extent. Additional simulations were performed using a Pseudo Global Warming (PGW) approach with future climate deltas derived from 30 CMIP6 global climate models under SSP2-4.5. Results show that wetlands reduce surface temperatures by 1 to 3°C on average, with broader cooling effects extending beyond wetland boundaries. Under future warming, these cooling effects persist, demonstrating the resilience of wetland-regulated climate moderation. The combined scenario of climate warming and wetland loss produces amplified heat exposure. Although the reduction in Wet Bulb Globe Temperature (WBGT) due to wetlands was modest (1–2°C), it has meaningful implications for heat stress mitigation. This study underscores the importance of wetlands as a natural defense against heat extremes and introduces a replicable framework for integrating wetland changes into regional climate modeling. These findings highlight the need to preserve and restore wetland ecosystems as part of climate adaptation strategies in heat-vulnerable regions.