NASA scientists have confirmed that China’s colossal Three Gorges Dam has had a measurable impact on the Earth’s rotation and axial tilt, making it the first known instance of a human-made structure influencing the planet’s geophysical parameters.
According to a report from NASA’s Earth Science Division, the mass displacement caused by the dam’s reservoir — which holds over 40 billion cubic meters of water — has slightly slowed Earth’s rotation and shifted its axis by approximately 2.5 centimeters.
The phenomenon has led to a minute increase in the length of a day, by about 0.06 microseconds, a change that is undetectable in daily life but observable through high-precision satellite measurements.
“The redistribution of mass near the equator increases Earth’s moment of inertia, which results in a slower rotation,” NASA researchers explained. “It’s comparable to a figure skater extending their arms to decelerate.”
The Three Gorges Dam, situated on the Yangtze River, is the largest hydroelectric power plant in the world, with a generating capacity of 22,500 megawatts. Operational since 2003, it provides about 2% of China’s electricity, while also serving functions in flood control, shipping, and regional power supply.
Though the impact on Earth’s rotation is scientifically minor, experts stress the symbolic weight of the findings.
“This marks the first time we’ve documented planetary-level consequences from a single piece of infrastructure,” said a NASA geophysicist involved in the study.
The data was collected via satellite geodesy systems, including GRACE (Gravity Recovery and Climate Experiment), which track subtle shifts in Earth’s gravity and mass distribution.
Beyond its geophysical effects, the Three Gorges project has sparked decades of internal debate in China. The construction led to the relocation of over a million residents, the flooding of historic and cultural sites, and concerns over seismic activity triggered by the weight of the reservoir on fault lines.
Despite this, Chinese authorities have long framed the dam as a symbol of national progress and a pillar of the country’s energy infrastructure.
NASA emphasized that while the change in Earth’s axis and rotation poses no risk to global systems such as navigation or satellite alignment, it illustrates the cumulative potential of human interventions on a planetary scale.
“It’s a reminder that we are not just observers of Earth’s systems — we are participants,” the agency noted.
