Projected effects of climate change on meteorological droughts over China: A study based on high-resolution NEX-GDDP data Journal of Hydrometeorology

While historical observations reveal increases in meteorological drought frequency across China during 1960-2021, future drought characteristics at the regional scale are uncertain. We evaluate historic and 21st century-projected dryness changes using the NASA Earth Exchange Global Daily Downscaled Projections (NEX-GDDP) 0.25deg resolution dataset for representation concentration pathway (RCP) 4.5 and 8.5. The 20 model NEX-GDDP ensemble mean precipitation and derived potential evapotranspiration, which is calculated by utilizing Thornthwaite approach, are consistent with gridded station data over China from 1961 to 2005. Results show that the projections of occurrence frequency of moderate drought based on standardized precipitation evapotranspiration index (SPEI) increase remarkably under RCP4.5 scenario, and the significant increasing frequency is seen for severe drought under RCP8.5 scenario, while few extreme dryness occurs during the 21st century under both emission scenarios. More moderate drought projections are found over northwestern, northern, and southeastern regions under RCP4.5 scenario, but the entire China will face severe droughts for RCP8.5. The areas affected by moderate droughts begin to extend rapidly around 2030s at both national and regional scales for RCP4.5 scenario, and the substantial increases in drying area extension for RCP 8.5 appears around 2050s. Particularly, the severe drought areas are found to grow much sharply after the 2070s under RCP 8.5 scenario, implying that the occurrences of severe droughts over China are more sensitive to greenhouse gas emissions.