Li-Ling Chang, Ruiqiang Yuan, Hoshin V. Gupta, C.L. Winter, and Guo-Yue Niu
In a warming climate, the global water cycle fed with more atmospheric water vapor is expected to intensify, causing dry regions to become drier and wet regions wetter. This “dry gets drier, wet gets wetter” (DDWW) paradigm is robustly supported by evidence over the oceans but remains uncertain over land when using evaluations based on precipitation, evapotranspiration and soil moisture data, suffering from limited coverage and accuracy. Here we use terrestrial water storage (TWS) anomaly data from the Gravity Recovery and Climate Experiment (GRACE) satellites to assess the DDWW paradigm regarding changes in areal extent and water depth over the period 2003 to 2016. Excluding cold regions, our analysis indicates that 45% of the global land area follows the DDWW paradigm, while only 35% shows an opposite pattern. Dry regions lost ~12.6 mm of water over the period 2003–2016, a loss rate comparable to the warming-induced melt of ice observed in cold regions (excluding Antarctic and Greenland). Meanwhile, wet regions gained ~3.1 mm. Further, when compared with local annual amplitudes, TWS trends are more readily apparent in dry regions than in wet regions, supporting the “dry gets drier” (DD) part of the paradigm.