Groundwater pumping appears to have nudged Earth’s rotational pole by about 31.5 inches between 1993 and 2010, according to a 2023 study that matched observed drift far better when it added human water loss to the model. The estimate also tied that underground depletion to 6.24 millimeters of global sea-level rise.
The finding is drawing attention now because it gives a number to something long suspected but never pinned down this clearly: that water moved from land to ocean can alter Earth’s spin. Earth’s rotational pole is not fixed in place, and it drifts and wobbles as mass shifts around the planet. A 2016 NASA description compared the effect to adding weight to one part of a spinning top, and that is close to what the researchers modeled here, using data from 1993 through 2010.
Ki-Weon Seo said the result answered a puzzle he had wanted to solve. He said he was glad to identify the cause of the rotation pole drift, and described groundwater redistribution as the climate-related factor with the biggest effect on the drift. The study estimated that humans depleted about 2,150 gigatons of groundwater over the period, much of it for irrigation and other human use, with the stored water eventually making its way to the oceans. Surendra Adhikari said the work quantified the role of groundwater pumping on polar motion, and said the impact was significant.
The model that best matched the observed drift pointed especially to heavy groundwater depletion in western North America and northwestern India. Those regions helped the estimate line up with the measured pole movement, but the fit was not a simple before-and-after picture of pumps yanking the planet off balance. The study was a model of observed changes, not a direct experiment, and the groundwater-loss scenario was only the best match among the climate-related causes considered.
That leaves the larger question open: how much of the pole drift over longer periods comes from groundwater depletion, and how much comes from other changes in terrestrial water storage? A 2026 reappraisal using the WaterGAP hydrological model found that terrestrial water storage matters for polar motion across different timescales, reinforcing the idea that shifting water — not just ice and air — can move the planet in measurable ways. Seo said he was concerned to see that pumping groundwater is also another source of sea-level rise, and the study’s answer is hard to ignore: human water use is now large enough to leave a trace in Earth’s rotation.
