Intensive extraction, evaporation, and groundwater loss driven by increasing temperatures are causing freshwater to flow from continents into oceans. This poses a significant risk to water supply for a large portion of the global population and contributes to rising sea levels.

Jay Famiglietty from Arizona State University and his team utilized satellite gravity measurements to assess changes in the total volume of water stored on land. This encompasses all types of freshwater, including rivers, underground aquifers, glaciers, and ice sheets.

Their findings reveal an unexpected reduction in freshwater resources across many regions worldwide from 2002 to 2024. Surprisingly, even arid areas are not experiencing increased dryness; the anticipated effects of climate change are extending over 800,000 square kilometers annually.

The researchers pinpointed four major “mega-dry” zones where distinct areas of freshwater depletion converge, leading to widespread aridification. These regions include Northern Canada and Russia, where losses are exacerbated by glacier retreat, thawing permafrost, and diminished snowfall.

In the remaining two regions, groundwater depletion resulting from agriculture is the primary cause of water loss. These areas, which cover much of the Southwestern U.S. and Central America, extend from Western Europe and North Africa to northern India and China. Groundwater depletion is worsened by heat and drought, compelling increased water extraction, which accounts for 68% of the total decline in water reserves.

This extensive water redistribution has become a significant contributor to sea level rise, adding nearly a millimeter to ocean levels each year since 2015, with terrestrial water losses outpacing those from Antarctic and Greenland ice melt.

According to the researchers, these patterns “likely convey a troubling message regarding the earlier effects of climate change.” They argue that “the continent is drying, freshwater resources are diminishing, and sea level rise is accelerating.”

While previous studies have identified these arid trends in specific areas, Manoochehr Shirzaei of Virginia Tech emphasizes that the strength of this research lies in its global perspective. “We’re not generating or losing water; we’re merely redistributing it. Unfortunately, this redistribution isn’t favoring the right areas,” he notes.

“The next step involves conducting a thorough analysis to isolate the factors driving groundwater depletion,” adds Benjamin Cook from Columbia University in New York. “It’s necessary to clarify the distinctions between the narratives of climate change and groundwater depletion.”