In the past, there were reports suggesting that China’s massive Three Gorges Dam could be slowing down Earth’s rotation slightly because of the way it changes inertia. But now, there’s growing talk among scientists that something else might be happening—and it’s making Earth spin faster instead.
As far back as 2023, researchers were puzzled over the sudden speed-up of Earth’s spin. Some believe global warming could be playing a role, especially with the melting of polar ice caps possibly affecting the planet’s momentum and rotation.
The differences may be small—just a drop of 1.30, 1.38, and 1.51 milliseconds on those respective days, but even these tiny shifts are enough to grab the attention of scientists around the world.
Why does it matter? Even a change of a millisecond can mess with important systems like satellite positioning and GPS. Leonid Zotov from Moscow State University weighed in with this striking statement: “Nobody expected this, the cause of this acceleration is not explained.”
But certain major natural disasters have been known to change that. A good example is the 2004 Indian Ocean earthquake and tsunami. It caused Earth’s tectonic plates to shift, and that alone shortened the average day by 2.68 microseconds.
This isn’t a one-off either. There’s been a pattern forming since 2020. On July 19 of that year, Earth spun 1.47 milliseconds faster than usual. It did the same again on July 9, 2021. Then on June 30, 2022, the record was broken with a 1.59 millisecond drop. And in 2024, multiple records were shattered yet again.
Scientists are still working on understanding what’s truly behind this speeding up. They’re keeping a close eye on several possible causes, including movements in the Earth’s inner core, changes in ocean circulation, and the impact of strong upper-atmosphere winds.
Right now, we keep global time using what’s called Coordinated Universal Time, or UTC. When needed, a leap second is added every so often to make up for small timing irregularities. But if Earth keeps speeding up, scientists may eventually need to do something they’ve never done before—introduce a negative leap second to keep everything in sync.