How Humanity’s Dams are Reshaping Earth’s Magnetic Poles: The Surprising Impact of Water Management

Recent studies reveal that human activities are influencing Earth’s magnetic field in notable ways. While it’s common for the planet’s magnetic poles to shift gradually, new findings indicate that the significant amount of water stored behind major dams is partly to blame for these changes.

Researchers from Harvard, led by geophysicist Natasha Valencic, found that the mass of water in nearly 7,000 large dams has shifted Earth’s rotational axis by about one meter (or three feet). This shift has inadvertently led to a 21-millimeter drop in global sea levels.

“As we store water in dams, it changes not just sea levels but also how mass is distributed across the planet,” Valencic explains. This alteration affects the positions of Earth’s magnetic poles relative to the surface.

When weight is added to a spinning object, it can alter the axis around which that object rotates. In this case, added water changes the distribution of mass on Earth, which can impact the position of the spin axis. While the magnetic north hasn’t physically moved, the surface of the Earth has shifted around it. This phenomenon is known as true polar wander.

Valencic and her team found that over time, the North Pole has moved in two distinct phases. From 1835 to 1954, it shifted east toward Russia by about 20 centimeters (8 inches) due to the construction of dams in Europe and North America. Then, from 1954 to 2011, it moved west toward North America by an additional 57 centimeters, influenced by new dams built in Asia and East Africa.

The researchers estimate that human activities have so far captured a quarter of the sea level rise this century—approximately 1.2 millimeters annually—within these reservoirs. While this may seem beneficial in the context of rising sea levels due to climate change, experts caution that it also requires careful consideration for future projections.

Interestingly, these findings highlight a broader trend. As humans continue to manage water resources, we are unintentionally affecting various planetary systems. These changes could complicate predictions about future sea levels and their impacts on coastal regions.

Overall, while damming water may help control floods and provide hydroelectric power, it also brings unintended consequences for our planet’s geology and environment.

This research was published in Geophysical Research Letters. For more on the impacts of human activity on climate, check the NRDC.

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