The Projected Response of the Water Cycle to Global Warming Over Drylands in East Asia

Abstract

AbstractClimate change exacerbates the threat of water scarcity over the drylands in East Asia (DEA), the world's most densely populated arid region. The water cycle continuously supplies water to support all life. Previous studies have focused on the change in individual hydrological components over DEA; however, how the projected water cycle changes under climate warming remains unclear. We demonstrate the projected response of the water cycle to global warming in different seasons utilizing the Coupled Model Intercomparison Project Phase 6. Winter in the DEA presents an intensification of the water cycle, reflected in coherent increases in evapotranspiration (E), precipitation (P), runoff, and surface soil moisture. In contrast, summer will experience a weakened water cycle in the northwestern DEA, while the southeastern part exhibits the opposite trend. From the surface and atmospheric water balance perspective, we further attribute the changes in E and P to gain a more comprehensive understanding. The increasing E is attributed to the combined effects of P and the vapor pressure deficit during summer, whereas it is dominated by P in winter. The increased P in summer is primarily attributed to the horizontal dynamic and vertical thermodynamic components associated with the strengthening and westward expansion of East Asia summer monsoon in the future. During winter, the increased P is mainly due to the vertical dynamic and horizontal thermodynamic components associated with the enhancement of vertical ascending motion and increased moisture.