Increasing precipitation variability on daily-to-multiyear timescales in a warmer world

Abstract

The hydrological cycle intensifies under global warming with precipitation increases. How the increased precipitation varies temporally at a given location has vital implications for regional climates and ecosystem services. Based on ensemble climate model projections under a high emission scenario, here we show that approximately two-thirds of land on Earth will face a “wetter and more variable” hydroclimate on daily to multiyear timescales. This means wider swings between wet and dry extremes. Such an amplification of precipitation variability is particularly prominent over climatologically wet regions, with percentage increases in variability more than twice those in mean precipitation. Thermodynamic effects, linked to increased moisture availability, increase precipitation variability uniformly everywhere. It is the dynamic effects (negative) linked to weakened circulation variability that make precipitation variability changes strongly region dependent. The increase in precipitation variability poses a new challenge to the climate resilience of infrastructures and human society.