New research reveals a startling global water shift: as soil dries out, massive volumes of land water are flowing into the oceans, silently accelerating sea level rise.
Key Points at a Glance
- PolyU-led study finds a dramatic global drop in soil moisture over four decades.
- Depleted land water is migrating into oceans, causing significant sea level rise.
- Between 2000 and 2002, 1,614 billion tons of land water entered the oceans.
- Climate-driven rainfall shifts and warming oceans identified as key culprits.
- Findings call for improved water models and global drought mitigation strategies.
For decades, scientists have sounded the alarm about melting glaciers and ice sheets as major contributors to rising seas. But a new study from The Hong Kong Polytechnic University (PolyU) adds a surprising twist to the story: the drying of the Earth itself—specifically its soil—is accelerating sea level rise in a way we’ve barely begun to grasp.
According to a global-scale study led by Professor Jianli Chen and a team of international researchers, the planet’s terrestrial water storage—water held in soil, groundwater, and vegetation—has experienced a sharp and sustained decline over the past 40 years. This hidden hydrological shift is responsible for releasing vast amounts of land-stored water into the oceans, significantly elevating sea levels.
The research, published in Science, harnessed cutting-edge space geodetic technologies—including data from satellite missions like GRACE and GRACE Follow-On—to measure variations in terrestrial water storage on a continental scale. These insights were cross-referenced with sea level data and even polar motion—how Earth’s axis of rotation subtly shifts in response to mass redistribution. The result? A clear, measurable global signal of water migrating from land to sea.
Between 2000 and 2002 alone, the team estimates that 1,614 billion tons of water left the soil and flowed into the oceans—causing a sea level rise of approximately 4.5 millimeters. That’s more than double the annual contribution from Greenland’s ice sheet during the same period. Alarmingly, since that sharp drop, the trend has continued steadily, showing no signs of recovery.
“This research reveals that we are literally draining our continents,” said Prof. Chen. “The drying of soil on a planetary scale is reshaping how water moves through Earth’s systems—and it’s showing up in our oceans.”
The underlying causes include a mix of natural variability and climate-driven forces: shifting rainfall patterns, rising global temperatures, and increasingly erratic evapotranspiration—the process by which water evaporates from soil and transpires through plants. These dynamics have created large-scale precipitation deficits that outpace water replenishment, especially in agricultural and semi-arid regions.
The study notes significant losses in soil moisture across Asia, Europe, Africa, and South America. In Asia, for instance, depletion expanded from northeastern areas to include much of East and Central Asia. In Europe, localized losses evolved into continent-wide dryness.
One striking piece of evidence came from Earth’s own wobble. From 2003 to 2011, the geographic North Pole shifted 58 centimeters toward 93° East—a clear signal that water mass was redistributing from land to sea.
Beyond the scientific intrigue, these findings carry enormous practical implications. Water resource management, agricultural planning, and climate mitigation efforts all depend on understanding how much water remains on land. With growing demand for irrigation in regions like northeast China and the western U.S., and widespread “global greening” driven by elevated CO₂ levels, the risk of continued moisture loss looms large.
To address this, the researchers advocate for more advanced land surface models that integrate not only climate data but also human impacts like irrigation and land use change. Without these enhancements, current climate models may dramatically underestimate how soil moisture decline contributes to sea level rise and long-term drought risk.
“This is about more than water—it’s about mass, movement, and the future of Earth’s balance,” Prof. Chen said. “With the right tools and data, we can track these shifts in real time and use that knowledge to build resilience against climate threats.”
As our oceans silently swell, the Earth’s soil is telling a quieter but no less urgent story. And with this new lens on global water loss, the challenge of protecting life on land becomes ever more deeply tied to the state of what lies beneath our feet.”
Source: The Hong Kong Polytechnic University
Enjoying our articles?
We don’t show ads — so you can focus entirely on the story, without pop-ups or distractions. We don’t do sponsored content either, because we want to stay objective and only write about what truly fascinates us. If you’d like to help us keep going — buy us a coffee. It’s a small gesture that means a lot. Click here – Thank You!
