Earth’s rotation is not perfectly stable, and scientists have long known that mass redistribution—like melting glaciers—can affect the way our planet spins. But a new study published in Geophysical Research Letters has pinpointed a more immediate trigger: the enormous volumes of groundwater being removed for irrigation and urban use, especially in certain midlatitude regions. Between 1993 and 2010, an estimated 2,150 gigatons of groundwater were pumped, eventually making their way into the oceans.
The consequences are twofold: not only does this contribute to global sea-level rise—about 0.24 inches over the period studied—but it also alters the Earth’s rotational pole, the axis around which the planet spins. This shift, while imperceptible to us day to day, is a stark example of how deeply human activity is entwined with the mechanics of the planet itself.
Pumping Groundwater Pushes the Planet off Balance
The study, led by Ki-Weon Seo, a geophysicist at Seoul National University, provides the most precise estimate to date of how human water use affects the Earth’s axis. Speaking about the findings, Seo explained that “among climate-related causes, the redistribution of groundwater actually has the largest impact on the drift of the rotational pole.” His team used observational data between 1993 and 2010 to simulate water movement and its effects on Earth’s spin.
The only model that matched the observed drift was the one that factored in the 2,150 gigatons of extracted groundwater, confirming that water removal was the primary driver of the shift. This redistribution of mass acts similarly to adjusting weight on a spinning top: “the Earth spins a little differently as water is moved around,” the study authors note.
These findings build on previous research from NASA in 2016, which had already demonstrated that water distribution can affect Earth’s rotation. But Seo’s study quantifies that effect with hard numbers, turning a previously observed trend into a clearly measurable outcome.
Sea-Level Rise and Groundwater Loss Are Now Inseparable
Once pumped from aquifers and used for agriculture or human consumption, groundwater doesn’t disappear—it ends up in the ocean, adding to rising sea levels. The study calculated this contribution at 0.24 inches over the 17-year period. While this might seem small, it’s part of a complex, accelerating pattern that amplifies global climate impacts.
According to NASA’s Surendra Adhikari, who contributed to the earlier 2016 study, this new research is significant because “they’ve quantified the role of groundwater pumping on polar motion, and it’s pretty significant.” It also provides a rare look into how terrestrial water storage changes translate into global environmental consequences.
Critically, the impact depends heavily on where the water is being moved from. The redistribution from midlatitude areas—especially western North America and northwestern India—was found to have the most influence on the shift in Earth’s axis, due to the geographical positioning and volume of extraction.
Tracking Earth’s Pole Movement Offers a Window Into Water Use
Observing how Earth’s pole moves is no longer just a geophysical curiosity—it’s a practical tool for understanding water storage changes on a continental scale. “Observing changes in Earth’s rotational pole is useful,” Seo stated, “for understanding continent-scale water storage variations.”
This approach opens the door for historical analysis, allowing researchers to dig deeper into decades of data and trace how human activity has steadily influenced the planet’s orientation. It could also enhance future water management strategies by showing where withdrawals are having the greatest planetary impact.