Guwahati: The construction of thousands of dams around the world since the 19th century has caused Earth’s poles to shift by more than 3.7 feet, according to new research published in the journal Geophysical Research Letters.
The study suggests that dams, which store massive volumes of water, have redistributed the planet’s mass enough to affect the orientation of Earth’s rotation axis—a phenomenon known as “true polar wander.” This occurs when the position of the Earth’s crust shifts relative to the mantle, causing the poles to move.
Ready for a challenge? Click here to take our quiz and show off your knowledge!
Researchers examined the impact of 6,862 dams built between 1835 and 2011. They found that storing water behind these dams not only led to a measurable decrease in global sea levels—by 0.9 inches (23 mm)—but also contributed to a significant drift in the geographic poles.
According to the study, the polar movement happened in two distinct phases. Between 1835 and 1954, major dam construction in North America and Europe pushed the North Pole around 8 inches (20 cm) closer to the 103rd meridian east, which passes through Russia, Mongolia, and China.
From 1954 to 2011, increased dam-building activity in East Africa and Asia led to a 22-inch (57 cm) shift of the North Pole toward the 117th meridian west, which cuts through western North America and the South Pacific.
Ready for a challenge? Click here to take our quiz and show off your knowledge!
Lead author Natasha Valencic, a graduate student at Harvard University, explained that while the pole’s movement is not likely to cause dramatic changes in the Earth’s systems, the impact of dams on sea levels is more significant. “We’re not going to drop into a new ice age, because the pole moved by about a meter in total, but it does have implications for sea level,” she said.
The researchers emphasize the need to factor in the role of dams in future sea level rise projections. Global sea levels rose by approximately 12 to 17 centimeters during the 20th century, and dams are estimated to have held back about a quarter of that water.
Valencic noted that while the pole’s migration follows a wobbly, non-linear path, the cumulative effect of dam-induced water storage on sea level and polar motion is considerable. “That’s another thing we need to consider, because these changes can be pretty large, pretty significant,” she added.