NASA researchers say people now leave a clear mark on where fresh water sits on the continents, and a pair of gravity-sensing satellite missions has shown where it is strongest. If you live near heavily irrigated farmland, that mark may be under your feet.
The study used measurements from GRACE and GRACE-FO, each a pair of satellites flying in tandem. When the lead satellite passes over an area with more mass, including heavy water and ice, gravity tugs on it slightly, and instruments track the changing distance between the two craft. The team covered April 2002 to November 2025.
A note on sourcing: this story rests on NASA's published summary of the work, not on the full paper. We could not confirm the journal, publication date or DOI, so the details below are preliminary.
What the researchers found
Beyond natural climate swings, the scientists identified 40 regions where storage changes also lined up with human activity such as irrigation, reservoir filling and land-use change. Those links showed up on every nonpolar continent except Australia.
In four continental regions, a human factor explained the trend better than any climate variable did, said Mary Michael O'Neill, a hydrologist at NASA's Goddard Space Flight Center and the study's lead author. Some farming and water management appears to have had the opposite effect, though the source text doesn't spell out where.
Where the groundwater is going
Across several continents, farmland watered from underground was strongly tied to falling storage. In North America that includes California's Central Valley, the southern High Plains and Chihuahua, Mexico, where long droughts have pushed farmers toward pumping.
Northern India stands out. The sharper analysis showed a steeper decline than earlier estimates, and retreating Himalayan glaciers explain only 15 percent of it, in line with earlier findings.
Why this map is sharper
GRACE data is usually turned into monthly maps showing broad patterns. Here, the team combined every pass over two decades to map long-term trends with five to 10 times more spatial detail than earlier analyses. The cost was losing detail in time. Statistical methods then weighed human and climate factors.
Matthew Rodell, a Goddard co-author, said the finer detail exposed human impacts not previously detected, and showed some known trends were stronger than realized.
What is still unknown
NASA's summary doesn't list all 40 regions, give storage losses in volume, or say how confident the human attribution is region by region. Those details are expected to come with the full paper. An association is also not proof of cause, which is why the researchers describe where activities "may have contributed."
The next step is the full paper, which should carry the complete regional list, storage volumes and region-by-region confidence ranges. We could not find a release date for it, and we will update this story with the journal citation and numbers once it is out.
Sources
- 1.The Human Fingerprint on Earth’s Water Cycle - NASA Science · NASA Science
Reported by the WattsUpNext desk from the sources linked below. Spot an error? Tell us at corrections@wattsupnext.com.
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