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Editor’s summary

As climate has warmed, precipitation and evapotranspiration changes have affected land surface water fluxes. What impact has that had on terrestrial water storage, the amount of water stored on and in the land? Seo et al. combined soil moisture data from satellites, measurements of sea level, and observations of polar motion to estimate terrestrial water storage over the past four decades, which revealed a dramatic decline (see the Perspective by Samaniego). During the interval from 2000 to 2002, terrestrial water storage decreased by nearly twice as much as Greenland ice mass loss over the same period. —Jesse Smith

Abstract

Rising atmospheric and ocean temperatures have caused substantial changes in terrestrial water circulation and land surface water fluxes, such as precipitation and evapotranspiration, potentially leading to abrupt shifts in terrestrial water storage. The European Centre for Medium-Range Weather Forecasts (ECMWF) Reanalysis v5 (ERA5) soil moisture (SM) product reveals a sharp depletion during the early 21st century. During the period 2000 to 2002, soil moisture declined by approximately 1614 gigatonnes, much larger than Greenland’s ice loss of about 900 gigatonnes (2002–2006). From 2003 to 2016, SM depletion continued, with an additional 1009-gigatonne loss. This depletion is supported by two independent observations of global mean sea level rise (~4.4 millimeters) and Earth’s pole shift (~45 centimeters). Precipitation deficits and stable evapotranspiration likely caused this decline, and SM has not recovered as of 2021, with future recovery unlikely under present climate conditions.