Viral Claim About China’s Three Gorges Dam Shifting Earth’s Axis Is Misleading

A viral social media post claims that the US space agency NASA confirmed the Three Gorges Dam in China shifted the Earth’s rotation axis and made each day shorter. This has circulated widely on platforms. However, our investigation finds the claim is misleading.

Social Media Posts

Screenshots of posts show captions like: “NASA confirms a giant dam shifted Earth’s axis and made days shorter.” These posts have gained traction across social media platforms, with many users expressing concern about the dam’s alleged environmental impact.

Source | Archive

Source | Archive

Fact Check

What the scientific sources actually say

NASA’s Jet Propulsion Laboratory explains that moving large amounts of mass on Earth, whether through major earthquakes or by filling huge reservoirs with water, affects the planet’s moment of inertia, which in turn alters its rotation. In a 2005 JPL note, NASA scientists used the Three Gorges reservoir as an example for their calculations: if the reservoir were completely filled with its roughly 40 cubic kilometers of water, it would slightly increase the length of each day by about 0.06 microseconds and shift Earth’s rotational pole by approximately 2 centimeters. This is a theoretical estimate based on mathematical models, not a measured observation of an actual change caused by the dam.

Science Focus, who reference the same NASA calculation clarify the direction and magnitude: Chao’s estimate suggests a day becomes longer by approximately 0.06 microseconds, around 60 billionths of a second, an amount far below everyday detectability. These sources present the NASA modelling and note how small the effect is.

What the claim gets wrong

The viral posts claim that NASA “confirmed” the Three Gorges Dam shifted Earth’s axis and made days shorter. In reality, NASA provided a theoretical calculation, not an observational confirmation. According to NASA’s model, filling the dam’s reservoir would make days slightly longer, not shorter, by about 0.06 microseconds (60 billionths of a second) and shift Earth’s rotational pole by roughly 2 centimeters.

The earthquake comparison clarifies this misunderstanding. Major earthquakes like the 2011 Tōhoku and 2004 Sumatra events actually made days shorter by about 1.8 and 2.68 microseconds respectively, because they redistributed Earth’s mass inward. The Three Gorges Dam does the opposite, spreading mass outward in the reservoir, which would make days marginally longer instead. The viral claim not only misrepresents NASA’s theoretical work as confirmed fact, but also gets the direction of the effect backward.

Earth’s axis is an imaginary line running through the planet’s center from the North Pole to the South Pole, around which Earth rotates. The “rotational pole” is where this line meets Earth’s surface at the poles. When mass shifts on Earth (such as water filling a reservoir, ice melting, or tectonic plates moving), the rotational pole can move slightly, which can be described as a wobble, without the entire axis dramatically tilting. When scientists predict a ~2-cm shift of the pole, they are describing a small movement of that surface point, not the axis flipping or tilting in a major way.

This distinction matters when evaluating claims about large dams “moving Earth’s axis.” What scientists actually measure are very small adjustments in the rotational pole’s position or changes in Earth’s moment of inertia, not a dramatic reorientation of how Earth spins. (Source)

Additional context and scale

To put this in perspective, NASA’s recent research on climate-related mass shifts (like melting ice sheets) shows these effects can alter Earth’s rotation by milliseconds per century, much larger than any single dam could achieve, yet still too small to notice in everyday life. These changes only matter for highly precise timekeeping systems. By comparison, the Three Gorges Dam’s effect is thousands of times smaller than these climate-driven changes.

To put it simply, NASA did not confirm through observation that China’s dam shortened the day or significantly shifted Earth’s axis. Instead, NASA scientists performed a theoretical calculation showing that the dam’s reservoir would make days very slightly longer (by about 0.06 microseconds) and shift the pole by roughly 2 centimeters. These changes are far too small to affect anything beyond specialized scientific measurements.

Conclusion

The viral claim that NASA confirmed the Three Gorges Dam in China shortened Earth’s rotation and shifted its axis is misleading. NASA’s theoretical calculations indicate that the dam’s reservoir would actually make days slightly longer by approximately 0.06 microseconds and shift the rotational pole by about 2 centimeters, effects far too small to be observable in daily life.