We are undergoing unprecedented loss of freshwater across the planet

The pumping, evaporation and intensive merger of groundwater due to the increase in global temperatures have changed an increasing quantity of freshwater from continents to the oceans. This threatens water availability for most of the world’s population and adds to the elevation of sea level.

Jay Famiglietti on Arizona State University and its colleagues used satellite gravity measurements to estimate changes in the total amount of water mass stored on continents. This includes all forms of fresh water, rivers and underground aquifers with glaciers and ice caps.

These measures show that there have been alarming freshwater reductions in many regions of the world between 2002 and 2024. Researchers have found that dry regions are not only dry – an expected trend with climate change – they also develop by more than 800,000 square kilometers per year, an area of the size of the United Kingdom and combined France.

The team has identified four regions of “mega-scagging” where areas separated from freshwater loss have now been connected to create a drying strip. These include northern Canada and Russia, where the loss is driven by the melting of glaciers, permafrost and reduced snow.

In the other two regions, the loss of water is dominated by the exhaustion of groundwater, mainly pumping for irrigation. It is the American Southwest, a large part of Central America and a region that extends from Western Europe and North Africa to north of India and China. They found a depletion of groundwater, which can be exacerbated by heat and drought encouraging people to pump more, represents 68% of the drop in overall water storage.

This mass transfer is so great that it has become a major contributor to the elevation of sea level. They have found that since 2015, the water loss of continents has caused a greater increase in the sea level than the cast iron water from the glacial calculations of Antarctica or Greenland, increasing the oceans by just under one millimeter per year.

These trends together “perhaps send the most recent message on the impact of climate change to date”, the researchers write in their report. “Continents dry, the availability of fresh water shrinks and the elevation of sea level is accelerating.”

We already knew these drying trends in many individual regions, explains Manoochehr Shirzaei at the Virginia Polytechnic Institute and State University. But he says that the power of this research comes from his global vision of the problem. “We do not produce water or destroy water. We are only redistributing water. But the redistribution is not going in the right direction, ”he says.

“The next step is really to make the detailed diagnosis to really separate what stimulates the depletion of groundwater,” said Benjamin Cook at Columbia University in New York. “It would take a little more details to separate history from climate change from the history of depletion of groundwater.”