Massive Dams Have Shifted Earth’s Geographic Poles, Study Finds

Arecent scientific study has revealed that the construction of thousands of dams over the past two centuries has caused a measurable shift in Earth’s geographic poles — by approximately one meter. The findings offer a striking example of how human activity is altering planetary dynamics.

According to researchers publishing in Geophysical Research Letters, the redistribution of massive volumes of water stored in artificial reservoirs has changed Earth’s mass balance. This shift in mass has altered the orientation of the planet’s rotation axis relative to the Earth’s crust.

To illustrate the phenomenon, the researchers offered a simple analogy: if you stick a small piece of modeling clay on a spinning basketball, the ball will tilt slightly to preserve its angular momentum — even if its spin axis stays in place. Similarly, “any shift in mass inside or on the surface of Earth affects the position of the rotation axis in relation to the crust,” the team explained.

The study relied on a global database of over 7,000 reservoirs, whose combined water volume would be enough to raise global sea levels by 21 millimeters if released. Calculations indicate that between 1825 and 2011, the geographic poles moved by 113 centimeters — with 104 of those centimeters occurring during the 20th century alone, a time of massive dam-building projects worldwide.

These results suggest that dams must be factored into future projections for sea level rise, alongside climate change. The authors warn that the pooling of freshwater inland has significant and previously underappreciated consequences for Earth’s orientation.

Other natural phenomena also contribute to polar drift, such as mantle and core motion, the rebound of land previously compressed by ancient glaciers, and large earthquakes.

However, human influence is becoming increasingly dominant. A 2016 study showed that the melting of Greenland’s ice sheets — driven by global warming — shifted the poles by several meters. Another study in 2023 found that the large-scale pumping of groundwater moved the poles by 80 centimeters between 1993 and 2010.