Melting Ice Caps Are Altering the Speed of Earth’s Rotation

The planet’s day is currently lengthening at a rate of roughly 1.33 milliseconds per century. This shift stems from the movement of mass away from the poles toward the equator as glaciers and ice sheets melt. The added volume in the oceans causes Earth to bulge slightly at its midsection, creating a braking effect that slows the rotation. While this alteration seems negligible on a human scale, it creates significant friction for satellite navigation, deep-space communication, and high-precision global timekeeping.

To map this trend, scientists analyzed fossilized benthic foraminifera to reconstruct historical rotation data spanning 3.6 million years. The findings, published in the Journal of Geophysical Research: Solid Earth, indicate that the acceleration observed between 2000 and 2020 is historically unprecedented. If current climate trajectories continue, the human-driven impact on Earth’s rotation could surpass the Moon’s primary influence by the end of the century.