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New scientific research has revealed that human activity is now altering one of the most fundamental properties of our planet: the speed at which Earth rotates on its axis. According to a study published in March 2026 by researchers from the University of Vienna and ETH Zurich, the length of a day has been increasing at a pace that is unmatched over at least the past 3.6 million years. Between 2000 and 2020, the average length of a day grew by approximately 1.33 milliseconds per century – a direct consequence of massive polar ice melt and glacier retreat caused by global warming. This tiny but measurable change is already influencing precision timekeeping systems around the world.

The “Figure Skater Effect” in Action

The mechanism behind this slowdown is straightforward and elegant. As vast quantities of ice from Greenland, Antarctica, and mountain glaciers melt, the resulting water flows from the poles toward lower latitudes and spreads out more evenly around the equator. This redistribution of mass increases Earth’s moment of inertia – the rotational equivalent of mass being farther from the axis of rotation. Just as a figure skater spins more slowly when they extend their arms outward (moving mass farther from the center of their body), Earth spins more slowly when more of its mass is shifted toward the equator. Lead researcher Mostafa Kiani Shahvandi from the University of Vienna explained “In our earlier work, we showed that the accelerated melting of polar ice sheets and mountain glaciers in the 21st century is raising sea levels, which slows Earth’s rotation and therefore lengthens the day similar to a figure skater who spins more slowly once they stretch their arms.”

A Historic Shift: Humans Overtaking the Moon

For billions of years, the dominant force gradually slowing Earth’s rotation has been tidal friction caused by the gravitational interaction between Earth and the Moon. This process has been lengthening days by roughly 2.4 milliseconds per century over geological timescales. However, the modern climate-driven acceleration is so rapid that scientists now project climate change could become the primary driver of Earth’s rotational slowdown by the end of the 21st century. If current emission trends continue, projections indicate that climate impacts alone could contribute an additional 2.62 milliseconds of day-length increase by 2100 – surpassing the Moon’s long-term influence.

Reconstructing Millions of Years of Rotation History

To determine whether anything like this has happened before, the team analyzed chemical signatures preserved in the fossilized shells of tiny marine organisms called benthic foraminifera. These microscopic creatures record ancient sea-level changes in their shell chemistry, allowing scientists to reconstruct corresponding variations in Earth’s rotation rate.
The record shows that while day length has fluctuated over millions of years – particularly during ice-age cycles of the Quaternary period the sharp acceleration observed since the year 2000 stands out as exceptional in at least the past 3.6 million years, reaching back into the late Pliocene epoch.

Professor Benedikt Soja of ETH Zurich stated

“This rapid increase in day length implies that the rate of modern climate change has been unprecedented at least since the late Pliocene, 3.6 million years ago. The current rapid rise in day length can thus be attributed primarily to human influences.” Real-World Consequences: From Leap Seconds to GPS although an extra 1.33 milliseconds per century is imperceptible in daily life, it creates significant challenges for technologies that depend on ultra-precise synchronization with Earth’s rotation.

Systems affected include

GPS satellites and other space navigation platforms deep-space missions high-frequency financial trading networks telecommunications infrastructure.The cumulative effect has already forced adjustments to global time standards. The previously anticipated introduction of a negative leap second (subtracting one second from clocks to keep them aligned with Earth’s slowing rotation) has been delayed – from an expected date around 2026 to at least 2029 – largely because of this climate-induced additional slowdown. Looking Ahea While the changes remain far too small to influence human sleep cycles, circadian rhythms, or everyday experience, they serve as another stark indicator of how profoundly human greenhouse gas emissions are reshaping the physical Earth system. As melting continues and sea levels rise, the planet’s spin will slow further – quietly but relentlessly reminding us that even the length of our days is no longer entirely governed by celestial mechanics alone. The era in which natural astronomical forces were the sole architects of Earth’s rotation may be coming to an end.