Less reliable water availability predicted in 21st century

A study published in the journal Earth’s Future finds water availability will be less reliable in the 21st century with predicted changes to global climate. The reduced reliability depends largely on expected increases to evapotranspiration, authors say.

Evapotranspiration is the sum of water evaporated from water bodies and transpired by plants. Even though precipitation is expected to increase in some regions, researchers found that warmer temperatures will impact humidity more, which could increase evapotranspiration. Study authors say these results mean that wet seasons will be wetter and dry seasons will be drier.

Researchers based their findings on an index that accounts for seasonal changes in precipitation and evapotranspiration that they applied to global regions. They note that the index, built around the results of 20 climate models, doesn’t account for predicted gains in human populations, which will likely increase demands on water resources worldwide.

Scientists from George Mason University, the National Center for Atmospheric Research and Princeton University contributed to the study.