Will the water supply run out? NASA satellites show a dramatic drop in freshwater worldwide since 2014, which is attributed to climate change.

The amount of freshwater stored on land, including lakes, rivers, and groundwater, was 290 cubic miles (1,200 cubic kilometers) less from 2015 to 2023 than the average from 2002 to 2014, according to satellite data.

Earth's total freshwater supply started to drastically decrease in May 2014 and has remained at lower levels ever since, according to evidence discovered by an international team of scientists analyzing data from German and NASA satellites.

According to a study that was published in Surveys in Geophysics, this change may indicate that the continents of Earth are about to experience a protracted dry spell.

The amount of freshwater stored on land, including lakes, rivers, and groundwater, was 290 cubic miles (1,200 cubic kilometers) less from 2015 to 2023 than the average from 2002 to 2014, according to satellite data. This is the equivalent of losing 2.5 times the volume of Lake Erie, said Matthew Rodell, a NASA hydrologist and co-author of the study.

According to the report, farms and cities are depending more and more on groundwater during droughts, particularly as irrigated agriculture grows. This leads to a loop of diminishing water supplies: more groundwater is withdrawn, freshwater supplies run low, and rainfall and snowfall are unable to restore them.

According to a 2024 UN assessment on water stress, the ensuing water shortages can significantly strain communities and agriculture, increasing the danger of hunger, violence, poverty, and disease, particularly when people turn to contaminated water sources.

Using information from the Gravity Recovery and Climate Experiment (GRACE) satellites, a collaborative mission between NASA and the German Aerospace Center, the researchers monitored the global decline in freshwater.

Changes in the bulk of water on and below the surface are revealed by GRACE satellites, which track variations in Earth's gravity. The GRACE–Follow On (GRACE–FO) satellites, which were deployed in 2018, are still monitoring the planet's water levels, while the original GRACE satellites were in operation from 2002 to 2017.

Significant droughts in Australasia, South America, North America, Europe, and Africa followed the catastrophic drought that started the freshwater reduction in northern and central Brazil. A significant El Niño event from late 2014 to 2016 was influenced by abnormally warm tropical Pacific ocean temperatures, which were linked to these droughts. By altering atmospheric jet streams, this weather phenomena disturbed rainfall patterns all around the planet.

Even after the El Niño of 2015–2016 subsided, freshwater levels around the world did not rise again. Indeed, the analysis discovered that since 2015, 13 of the 30 most severe droughts identified by the GRACE satellites had taken place. Rodell and his associates believe that the continuous loss of freshwater might be caused by climate change.

More water vapor is held in the atmosphere as a result of global warming, which increases the frequency of extreme weather events like heavy rains. Longer dry periods in between intense downpours, however, limit soil's ability to absorb water, which makes it more difficult for groundwater to refill, according to NASA meteorologist Michael Bosilovich. Bosilovich continued, "Water tends to run off rather than soak into the ground when there is extreme precipitation." This indicates that even though there is still more moisture in the atmosphere, less water is filling up subterranean reservoirs.

"Drought conditions are exacerbated by warming temperatures because they increase water evaporation and the atmosphere's capacity to retain moisture," Bosilovich said.

According to Susanna Werth, a hydrologist at Virginia Tech who was not involved in the study, there are signs that the loss of freshwater may be directly related to global warming, but it is difficult to make the connection. "Climate models and measurements have uncertainties," she clarified.

Whether global freshwater levels will stabilize, drop more, or return to pre-2015 levels is still up in the air. Rodell thinks the trend could be related to global warming because the beginning of the freshwater reduction coincides with the nine warmest years on record. We believe this to be a sign rather than a coincidence.