Satellites reveal a sudden drop in global freshwater levels

None of us can live without freshwater. It is, arguably, the most crucial natural resource we have.

But recent findings have set off alarm bells around the world. Scientists are gravely concerned. Once abundant, our global freshwater levels are now at serious risk.

Earth’s total freshwater levels

An international group of scientists analyzed data from NASA-German satellites and discovered that Earth’s total freshwater levels experienced a sudden drop beginning in May 2014, with no signs of recovery since.

The researchers propose that this decline might indicate that Earth’s continents have shifted into an enduringly drier state.

Matthew Rodell is a hydrologist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

“The average amount of freshwater stored on land – that includes liquid surface water like lakes and rivers, plus water in aquifers underground – was 290 cubic miles (1,200 cubic km) lower than the average levels from 2002 through 2014,” said Rodell.

“That’s two and a half times the volume of Lake Erie lost.”

Satellite data exposed water loss

The team used observations from the Gravity Recovery and Climate Experiment (GRACE) satellites, a joint effort by NASA and the German Aerospace Center, to identify this significant global decrease in freshwater.

The GRACE satellites, which operated from 2002 to 2017, measured changes in Earth’s gravity monthly, unveiling the shifts in water mass on and beneath the surface. The mission was succeeded by the GRACE–Follow On (GRACE–FO) satellites, which have been operational since May 2018.

These satellites revealed that the drop in freshwater began with a severe drought in northern and central Brazil, quickly followed by major droughts in Australasia, South America, North America, Europe, and Africa.

Warmer ocean temperatures in the tropical Pacific during the 2014–2016 El Niño, one of the most intense since 1950, played a critical role in shifting atmospheric jet streams and altering global weather and rainfall patterns.

Freshwater levels did not rebound

However, the most troubling finding came after the El Niño event subsided: global freshwater levels did not rebound. Rodell noted that 13 of the world’s 30 most intense droughts observed by GRACE occurred since January 2015.

This pattern raises concerns about whether global warming could be contributing to the sustained freshwater depletion.

“Warming temperatures increase both the evaporation of water from the surface to the atmosphere and the water-holding capacity of the atmosphere, increasing the frequency and intensity of drought conditions,” said NASA meteorologist Michael Bosilovich.

Freshwater decline and global warming

The relationship between global warming and freshwater loss becomes clearer when considering the impact of extreme weather.

“Global warming leads the atmosphere to hold more water vapor, which results in more extreme precipitation,” Bosilovich explained.

Although annual rain and snowfall totals may not change significantly, the time between these intense precipitation events can grow, causing the soil to dry out and become compact.

“The problem when you have extreme precipitation is the water ends up running off,” Bosilovich added, meaning it doesn’t soak into the ground and replenish critical groundwater reserves.

This vicious cycle poses significant threats to agriculture, communities, and global stability. During prolonged droughts, the strain on water supplies forces cities and farms to rely heavily on groundwater, creating a loop of unsustainable extraction.

The resulting depletion impacts farmers and communities, exacerbating poverty, health risks, and potential conflicts.

A 2024 UN report on water stress highlights that people facing severe water shortages may resort to contaminated water sources, increasing the risk of disease and famine.

The future of our water resources

While scientists suspect global warming plays a significant role in these shifts, definitive links remain complex due to uncertainties in climate predictions and models.

Susanna Werth, a hydrologist and remote sensing scientist at Virginia Tech who was not involved in the study, noted: “There are uncertainties in climate predictions. Measurements and models always come with errors.”

This complexity highlights the challenge of forecasting future freshwater trends.

The pressing question remains: will global freshwater levels recover, stabilize, or continue to decline?

Nine of the warmest years in recorded history coincided with this sharp drop in freshwater. “We don’t think this is a coincidence, and it could be a harbinger of what’s to come,” said Rodell.

The data emphasizes the urgent need for action and adaptation strategies as we face a potentially drier future.

The study is published in the journal Surveys in Geophysics.

—–

Like what you read? Subscribe to our newsletter for engaging articles, exclusive content, and the latest updates. 

Check us out on EarthSnap, a free app brought to you by Eric Ralls and Earth.com.

—–