Recent Decline in Global Ocean Evaporation Due To Wind Stilling

Abstract

Ocean evaporation (E_o) is the major source of atmospheric water vapor and precipitation. While it is widely recognized that E_o may increase in a warming climate, recent studies have reported a diminished increase in the global water vapor since ∼2000s, raising doubts about recent changes in E_o. Using satellite observations, here we show that while global E_o strongly increased from 1988 to 2017, the upward trend reversed in the late 2000s. Since then, two-thirds of the ocean have experienced weakened evaporation, leading to a slight decreasing trend in global-averaged E_o during 2008–2017. This suggests that even with saturated surface, a warmer climate does not always result in increased evaporation. The reversal in E_o trend is primarily attributed to wind stilling, which is likely tied to the Northern Oscillation Index shifting from positive to negative phases. These findings offer crucial insights into diverse responses of global hydrological cycle to climate change.