As Earth’s rotation speed slowed ever-so-slightly in recent decades, leap seconds were added intermittently to keep clocks up to date.
But if a new trend holds, time might need to be turned in the other direction some day soon.
Earlier this month, The Daily Telegraph reported that Earth has reached its quickest spin speeds in the past half-century.
“It’s quite possible that a negative leap second will be needed if Earth’s rotation rate increases further,” said Peter Whibberley, a senior research scientist with Britain’s National Physical Laboratory, according to The Daily Telegraph.
The speed of Earth’s spin fluctuates constantly due to a range of factors, including the motion of the planet’s core and oceans, according to the British newspaper.
The last leap second was added at the end of 2016, and the next leap second remains unscheduled, according to the International Earth Rotation and Reference Systems Service.