Groundwater Pumping Shifted Earth's Rotational Pole by 31.5 Inches — What That Means

Key finding: A new study in Geophysical Research Letters shows that large-scale extraction of groundwater between 1993 and 2010 redistributed roughly 2,150 gigatons of water and produced about 31.5 inches of polar shift — equivalent to roughly 0.24 inches of global sea-level rise.

How pumping groundwater alters Earth's spin

The redistribution of mass on Earth changes its rotation. The study’s authors compare the effect to adding a small weight to a spinning top: shifting water from continents to the oceans subtly changes how the planet wobbles and where its rotational pole sits.

“Earth’s rotational pole actually changes a lot,” says Ki‑Weon Seo, the study’s lead author and a geophysicist at Seoul National University. “Among climate-related causes, the redistribution of groundwater has the largest impact on the drift of the rotational pole.”

What the researchers did

The team analyzed observational data from 1993 through 2010 and tested multiple models of polar motion and water movement. Only models that included a redistribution of about 2,150 gigatons of groundwater — mainly withdrawn for irrigation and human use and later transported to the oceans — matched the observed pole drift.

Surendra Adhikari, a NASA Jet Propulsion Laboratory research scientist involved in earlier work on hydrologic effects on rotation, notes that the new study is important because it provides a quantified link between groundwater loss and polar motion.

Where the water came from — and why location matters

Mass moved from different latitudes has different effects on polar drift. The study finds that groundwater losses in the midlatitudes had a disproportionately large influence. In particular, heavy pumping in western North America and northwestern India helped drive much of the observed shift.

Implications for sea level and climate monitoring

Although the calculated contribution to global sea-level rise is small on its own (~0.24 inches), the finding matters for two reasons: it identifies a measurable human-driven component of polar motion, and it underscores how continental water use feeds into broader climate signals. Tracking polar motion can therefore help researchers monitor continent-scale changes in water storage.

The authors recommend combining modern observations with historical records to better understand long-term trends and to inform conservation strategies aimed at limiting further sea-level rise and other impacts of water redistribution.

Takeaway

Industrial-scale groundwater extraction has a detectable, quantifiable effect on Earth’s rotation and contributes modestly to sea-level rise. The study adds a clear, previously unexplained piece to the puzzle of polar drift and highlights the value of integrating hydrology and geophysics in climate monitoring.