China’s Mega-Dam Alters Earth’s Spin: Scientists Divided Over Planetary Consequences

China built a dam so massive it actually slowed down the planet. The Three Gorges Dam, stretching across the Yangtze River in Hubei province, holds 40 billion cubic metres of water. That’s enough liquid to mess with Earth’s rotation, according to NASA scientists who apparently have nothing better to do than measure microseconds.

The dam slowed Earth’s spin by 0.06 microseconds. Not exactly apocalyptic, but still. It’s the first time humans built something that actually changed how fast the planet spins. The physics behind it sounds like something from a high school textbook. When you redistribute mass across Earth’s surface, you change its moment of inertia. Think of an ice skater pulling their arms in to spin faster, except backwards and with billions of tons of water.

NASA scientist Benjamin Fong Chao confirmed the effect back in 2005. The water accumulating behind the dam shifted weight distribution across the planet. Mass moved toward the equator slows rotation. Mass toward the poles speeds it up. Simple enough, right? The same mass redistribution also shifted Earth’s pole position by approximately 2 centimeters.

The engineering specs are ridiculous. Standing 185 metres tall and spanning over 2 kilometres, this concrete beast generates 22,500 megawatts of electricity. In 2020, it cranked out 112 terawatt-hours, more power than some entire countries produce. The dam remains the largest hydroelectric project on Earth, dwarfing other power generation facilities worldwide.

The dam draws water from three gorges with names that sound like someone sneezed: Qutangxia, Wuxia, and Xilingxia.

For perspective, the 2004 Indian Ocean earthquake shortened Earth’s day by 2.68 microseconds through tectonic movement. The dam’s effect is smaller, but that was nature doing its thing. This is humans literally altering planetary physics with concrete and water.

Some reports claim the effect increases daylight by 0.06 milliseconds, though that’s probably stretching the significance. Modern instruments can detect these tiny changes, but you won’t notice your day getting longer.

The real story isn’t about time. It’s about scale. Humans built something so massive it affects how the planet spins. That’s either terrifying or impressive, depending on your perspective.