Accelerated Transition Between Dry and Wet Periods in a Warming Climate

The consecutive occurrence of meteorological dry and wet extremes has been receiving increasing attention due to potentially larger social and environmental impacts than single extremes. However, the changing characteristics of transitions between dry and wet periods remain poorly understood. Here we investigate the dynamic evolution of dry-to-wet transitions in response to climate warming, using the Standardized Precipitation Evapotranspiration Index as well as observations and general circulation models for the periods of 1954–2014 and 2040–2100. We find that approximately three-fifths of global land area are projected to experience an accelerated dry-to-wet transition. Southern Asia has been experiencing the most severe dry-to-wet transitions and is projected to suffer more frequent, more intense, and accelerated dry-to-wet transitions. The increasing potential evapotranspiration (PET) variability plays an important role in accelerating the dry-to-wet transition in Southern Asia, while precipitation and PET variabilities contribute to the intensification of dry-to-wet transitions in Southern North America.