SAN DIEGO, California: A study in the journal Nature just publishedhas stated that for the first time in history, Earth’s changing spin could force timekeepers to subtract a second from world clocks in a few years.
As the Earth rotates faster than it used to, clocks may have to skip a second, also known as a “negative leap second,” around 2029.
The study’s lead author Duncan Agnew, a geophysicist at the Scripps Institution of Oceanography at the University of California, San Diego, said, “This is an unprecedented situation and a big deal. It is not a huge change in the Earth’s rotation that is going to lead to some catastrophe or anything, but it is something notable. It is yet another indication that we arere in a very unusual time.”
Ice melting at both poles counteract the Earth’s burst of speed and delay this global second of reckoning by some three years, he added.
Dennis McCarthy, retired director of time for the US Naval Observatory, who was not part of the study, said, “We are headed toward a negative leap second. It is a matter of when.”
He added that it is a complicated situation that involves physics, global power politics, climate change, technology, and two types of time.
Agnew and Judah Levine, a physicist for the time and frequency division of the National Institute of Standards and Technology, said, “Earth takes about 24 hours to rotate, but for thousands of years, the Earth has been generally slowing down, with the rate varying from time to time.”
McCarthy said the slowing is mainly due to tides, which are caused by the moon’s pull.
This did not matter until atomic clocks were adopted as the official time standard more than 55 years ago, as those did not slow down.
Between 1972 and 2016, 27 separate leap seconds were added as Earth slowed. But the rate of slowing was tapering off.
“In 2016 or 2017 or maybe 2018, the slowdown rate had slowed down to the point that the Earth was actually speeding up,” Levine said.
Agnew said that Earth is speeding up because its hot liquid core, “a large ball of molten fluid,” acts in an unpredictable manner.
In 2022, the world’s timekeepers decided to change the standards for inserting or deleting a leap second from the 2030s.
Levine noted that tech companies, such as Google and Amazon, unilaterally instituted their own solutions by gradually adding fractions of a second over a full day.
“The fights are so serious because the stakes are so small,” he said.
