Polar Ice Melt Is Altering the Rotation of the Earth, Affecting Timekeeping


The Earth is spinning slightly faster than it was a few years ago, but the rapid melt of polar ice is keeping that acceleration in check, with consequences for timekeeping, a new study finds.

The planet’s solid inner core rotates unevenly, and at present it’s gaining pace, causing the Earth to spin faster. The acceleration is scarcely perceptible, but it’s enough to shorten the length of a day. That’s a problem for global timekeepers, who track time down to the tiniest fraction of a second, and on whom technologists rely to keep computer clocks in sync. Timekeepers would need to subtract one second from the calendar at the end of 2026 to keep clocks in line with the rotation of the planet.

They would, that is, were it not for the thawing of Greenland and Antarctica. For decades, meltwater has been flowing from the poles toward the equator, causing the Earth to grow thicker at the waistline. This extra girth at the middle is counteracting movement in the planet’s inner core. The upshot, according to a new study published in Nature, is that timekeepers won’t need to subtract a second from the calendar until 2029.

The missing second, when it comes, could rattle computer networks across the globe. Were it not for climate change, the study said, the problem would arise three years sooner.


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