Climate change has increased global evaporative demand except in South Asia
S. Karimzadeh (University of California, TU Delft - Team Koty McAllister, Aalto University)
Arman Ahmadi (University of California)
Dennis Baldocchi (University of California)
Joshua B. Fisher (Chapman University)
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Abstract
Climate change alters how strongly the atmosphere draws water from the land, yet a consistent global assessment of this evaporative demand has been lacking. Here, we analyze 45 years of climate data and global models to quantify trends in the key drivers—air temperature, humidity, radiation, wind speed, and cloud cover—that determine the atmosphere’s drying power. We find that evaporative demand has increased worldwide, indicating a stronger atmospheric thirst, except in South Asia, where it has declined. There, widespread irrigation has increased soil and air moisture, enhanced cloud formation, and reduced sunlight reaching the surface, counteracting the global signal. These contrasting trends reveal how human water use can locally reshape the climate’s influence on the water cycle.
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