Harvard study reveals human engineering shifts Earth’s North Pole

A new study led by researchers at Harvard University, and published in Geophysical Research Letters, reveals that the construction of around 7,000 dams between 1835 and 2011 has altered the Earth’s rotation.

By holding vast quantities of water behind concrete walls, these megastructures have redistributed mass on the planet’s surface, nudging the poles by about three feet (or 0.91 metres) through a phenomenon known as true polar wander.

To visualise it, picture spinning a basketball with a lump of clay stuck to one side. The ball shifts ever so slightly to compensate—and so does Earth, when water is locked away inland rather than flowing freely across its oceans.

A planet tilted by progress

Lead researcher and Harvard PhD student Natasha Valencic explains: “As we trap water behind dams, not only does it remove water from the oceans, thus leading to a global sea level fall, it also distributes mass in a different way around the world.”

Though the shift isn’t catastrophic—certainly not on a scale to cause ice ages or climate collapse—it’s not trivial either. The study estimates that dam-building has lowered global sea levels by approximately 0.83 inches (2.1 cm) due to the water held inland.

What’s striking is how closely this shift in the poles tracks with human industrialisation. From the 19th century through to the mid-20th, most dams were built in North America and Europe, which nudged the North Pole about 8 inches (20 cm) towards the 103rd meridian east. Later, as Asia and East Africa ramped up dam construction, the poles veered back 22 inches (56 cm) toward the 117th meridian west.

The three gorges example

Among the most influential structures is China’s Three Gorges Dam, the largest in the world. In 2005, NASA scientist Benjamin Fong Chao calculated that when filled to capacity, the dam alone slowed the Earth’s rotation by 0.06 microseconds—that’s 60 billionths of a second. Minuscule to humans, but not to a planet.

Of course, dams aren’t the only anthropogenic forces at play. A separate 2023 study estimated that pumping groundwater—particularly from underground aquifers—led to a loss of 2 trillion tonnes of water between 1993 and 2010. That alone caused the poles to shift 4.36 centimetres annually.

A planet we can tilt

Humanity’s capacity to reshape the planet has long been evident in atmospheric, geological, and ecological terms. But this research underscores a startling reality: we can now physically shift the axis of the Earth. That makes dam-building—often celebrated as a symbol of human ingenuity—both a marvel and a cautionary tale.

As we continue to understand the consequences of our infrastructural ambition, the hope is that future planning will more carefully consider not just the immediate benefits of controlling water—but the subtle, planetary consequences of doing so.

By Aghakazim Guliyev