UC Irvine

A question of water supplyAn acceleration of the global hydrological cycle, evapotranspiration included, is regarded as a key indicator of the impact of global warming on Earth's system. Evapotranspiration refers to the water that moves from Earth's land surface to the atmosphere through the combined effects of evaporation and plant transpiration. Martin Jung and colleagues use a data-driven machine-learning technique and a suite of process-based models to show that, between 1982 and 1997, evapotranspiration increased steadily with global warming. But since 1998, the increasing trend has flattened, probably as a result of limitations in soil-moisture supply in the Southern Hemisphere — particularly Africa and Australia. It remains to be seen whether this is part of a natural climate variation or a climate-change signal in which land evapotranspiration becomes more supply-limited in the long term.