So Much Polar Ice Is Melting That It’s Slowing Down the Earth’s Rotation

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Climate change is causing so much polar ice melt that it's slowing down Earth's rotation and — here's the kicker — it will alter how we measure time in the future.

That's the outrageous conclusion that Duncan Agnew, geophysicist and professor at University of California, San Diego, reached by analyzing data from satellite imagery, as detailed in a new study published in the journal Nature. 

Basically, as polar ice melts into the ocean, there's less mass overall at the poles and the middle of the planet becomes a little heavier, hence slowing down Earth's rotation.

"If you have a [figure] skater who starts spinning, if she lowers her arms or stretches out her legs, she will slow down," Agnew told NBC News, using ice skating as an analogy to what's happening to Earth's rotational velocity.


And that raises a problem for the measurement of time itself. If Earth's rotation is slowing down, that means timekeepers all over the world will have to adjust. This has impacts reaching far beyond our watches. It touches the functioning of satellites, computers, financial institutions and everywhere else where every second counts.

Institutions will likely have to adjust. The global time standard, known as Coordinated Universal Time or UTC, almost matches the Earth's rotation — but because the rotation speed can be variable, this has at times necessitated timekeepers to add or subtract a leap second to the clock, Agnew explains in his paper.

After crunching numbers, Agnew concluded that if polar ice did not melt, we would have had to subtract a second from clocks all over the world by 2026. But because of ice melt slowing down Earth's rotation, this time change may come instead in 2029, he said.

"It’s kind of impressive, even to me, we’ve done something that measurably changes how fast the Earth rotates," said Agnew to NBC News. "Things are happening that are unprecedented."

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