In a startling revelation, scientists have found that the construction of nearly 7,000 dams worldwide has caused Earth’s geographic poles to shift by almost one metre. This massive redistribution of water once stored in oceans, now trapped behind concrete has led to what scientists call a “true polar wander,” subtly altering the planet orientation.
Published in the Geophysical Research Letters, the study analysed the impact of 6,862 dams built between 1835 and 2011. Researchers noted that as water was stored on land, particularly in large reservoirs, it changed the distribution of mass on Earth surface enough to influence the planet’s spin axis. Between 1835 and 1954, the North Pole moved 20 cm east towards Russia due to dam construction in Europe and North America. Then between 1954 and 2011, as dam-building intensified in Asia and East Africa, the pole shifted 57 cm westward toward North America.
Lead author Natasha Valencic from Harvard University explained that this mass movement has even caused a 21-millimetre drop in global sea levels a significant offset, considering the average 1.2 millimetre rise per year in the 20th century. She stressed that while the shift won’t plunge the world into a new ice age, it does highlight how human infrastructure is now influencing Earth’s planetary mechanics.
“Every time we trap water behind a dam, we’re not just changing rivers we’re changing the Earth itself,” Valencic said. The findings add to the growing list of human-induced planetary shifts, from sea level changes and atmospheric alterations to disruptions in ocean circulation.
This research is a sobering reminder of the planetary-scale consequences of human activity, and why such effects must be factored into climate models and global sea level predictions moving forward.