A newly published scientific study in the journal Geophysical Research Letters has revealed a shocking truth: Thousands of giant dams built by humans over the past nearly 200 years are shifting the Earth's poles.
The study said that the huge amount of water accumulated behind dams has caused the Earth to "float to the poles" - a scientific phenomenon called true polar wander. The north pole of the Earth has shifted a total of 1.1m from 1835 to 2011 due to the influence of hydroelectric works and man-made reservoirs.
The mechanism is simple but unbelievable: When water is retained in huge reservoirs, this volume creates redistribution of matter on the planet's surface. The Earth's crust, which is located on a flexible coating below, will move slightly from the rotation axis. And over time, this phenomenon changes the relative position of the poles.
The team analyzed 6,862 dams globally, from the 19th century to the present, with enough water storage to fill the Grand Canyon canyons twice. This water level also caused global sea levels to drop by 2.3cm - an impact that is less mentioned when discussing climate change.
Of which, the Three Gorges Dam in China is one of the most influential projects. Considered the largest hydroelectric dam in the world, the Three Gorges Dam is over 2,300m long, 181m high, and the reservoir has a capacity of 39.3 billion m3 of water, equivalent to more than 15 million Olympic swimming lakes.
The extreme flow process is divided into two distinct stages: In 1835-54, the northernmost point moved 20cm east, due to the dam being concentrated in Europe and North America.
In the period of 1954-2011, the cucum continued to deviate by 57cm to the west, due to a series of large dams springing up in Asia and Africa.
Although the shift to the poles does not cause immediate danger, according to the research team, the impact on sea levels is worrying. In the 20th century, sea levels increased by 12-17cm, but about 25% of the water that should have flowed into the ocean is now retained behind dams. This could distort climate change forecast models if not taken into account.
We are not in the ice age just because of a 1m radius shift, but it is clear that this is a major impact that humans have on the planet, said Natasha Valencic, lead author of the study.
From water retention to the rotation of the earth's axis, super dams such as the Three Gorges Dam are proving one thing: human works are not only changing the landscape, but are also re-writing the geographical map of the Earth itself.
