Recent findings from an international team of scientists highlight a troubling shift in Earth’s freshwater availability. Using data from NASA-German satellites, the researchers discovered a significant decrease in the planet’s freshwater resources. This decrease has been persistent, beginning in May 2014. The drop, which has continued through 2023, may signal that Earth’s continents have entered a drier phase.
From 2015 to 2023, the total freshwater stored on land decreased significantly. This includes surface water such as lakes and rivers. It also includes underground water in aquifers. The amount was found to be 290 cubic miles (1,200 cubic km) lower than the average levels observed between 2002 and 2014. To put this into perspective, this loss is more than two and a half times the volume of Lake Erie. Matthew Rodell, a hydrologist at NASA’s Goddard Space Flight Center, provided this analysis. He is one of the study’s authors.
This sharp reduction in available freshwater is more than just an environmental issue. It has wide-reaching consequences for agriculture. It also impacts public health and global stability. During periods of drought, both cities and farms rely more on groundwater. This increased reliance, when excessive, worsens the depletion of underground water sources. If rain and snow do not replenish these resources, a dangerous cycle begins. Freshwater supplies continue to deplete. This depletion threatens food security, increases poverty, and heightens the risk of disease outbreaks from contaminated water sources.
A 2024 UN report on water stress further emphasizes the potential societal impacts of dwindling freshwater resources. It warns that long-term water scarcity could spark conflicts, worsen inequality, and lead to widespread suffering, especially in vulnerable regions.
UNDERSTANDING THE DECLINE: SATELLITE OBSERVATIONS AND CLIMATE SHIFTS
The team’s findings appeared in Surveys in Geophysics. They were based on data from the Gravity Recovery and Climate Experiment (GRACE) satellites. NASA and the German Aerospace Center operated these satellites. These satellites measure fluctuations in Earth’s gravity, which reveal changes in the mass of water on and below the surface.
The original GRACE satellites tracked water fluctuations across the globe from 2002 to 2017. They were followed by the GRACE-Follow On (GRACE-FO) satellites launched in 2018. The data revealed a sharp decline in freshwater. This decline began after a major drought in northern and central Brazil in 2014. Severe droughts quickly followed across Australasia, South America, and North America. They also struck Europe and Africa. The significant 2014-2016 El Niño event amplified these droughts.
Warmer ocean temperatures during this period caused shifts in atmospheric jet streams. These shifts disrupted global weather patterns. They also reduced rainfall in key regions. However, even after El Niño subsided, global freshwater levels did not recover. Rodell and his team noted a significant finding. They observed that 13 of the world’s 30 most intense droughts occurred since January 2015, as tracked by GRACE.
IS CLIMATE CHANGE TO BLAME?
The study raises concerns that global warming is playing a significant role in this ongoing depletion of freshwater. As the atmosphere warms, it can hold more water vapor, leading to more intense rainfall events. They also produce prolonged dry spells between these periods of heavy precipitation. While total annual rainfall might stay steady, the gaps between storms are extended. The soil dries out during these gaps. This reduction in moisture decreases its ability to absorb water when it does rain.
NASA’s Michael Bosilovich explains that this intensification of precipitation increases evaporation rates. More water evaporates back into the atmosphere, leaving less available to recharge groundwater supplies. As a result, more extreme weather events, including droughts, have become more frequent and severe.
There is evidence linking the decline in freshwater to global warming. But, some experts caution that it remains difficult to definitively prove the cause. “Climate predictions come with uncertainties,” says Susanna Werth. She is a hydrologist at Virginia Tech who was not involved in the study. “Measurements and models always come with errors, so it’s challenging to directly attribute the decline to climate change alone.”
THE FUTURE OF EARTH’S FRESHWATER RESOURCES
As scientists continue to monitor freshwater trends, the big question remains: Will global freshwater stores rebound to pre-2015 levels, stabilize, or continue to decline? The nine warmest years on record coincided with the steep decline in water resources. Rodell suggests the situation could be a harbinger of future conditions. It may possibly signal a long-term trend toward water scarcity.
Understanding and addressing the causes of freshwater loss is critical to mitigating its effects on both the environment and human populations. As climate change continues to affect weather patterns and water availability, global cooperation and effective water management will be essential in ensuring that freshwater resources remain available for future generations.
