On Thursday in Versailles, France, the General Conference on Weights and Measures voted by majority to stop adding "leap seconds" to the world's official clock. That clock is called Coordinated Universal Time (UTC). Starting May 20, 2027, it can drift up to an hour from the Earth's rotation before anyone corrects it. Since 1972, timekeepers have added 27 leap seconds to keep the clock in step with the Earth's slightly wobbly spin. The last one came at the end of 2016. People blamed leap seconds when Reddit and LinkedIn crashed in 2012. The Earth has sped up lately, so the next one might have had to take a second away. Nobody has ever done that. Russia had asked for more time to adapt. Its GLONASS satellite system builds leap seconds in.

This Was the Safe Call for the World's Computers (Patrizia Tavella, Setnam Shemar, Peter McDowall)

Timekeepers say leap seconds break computer systems, and deleting one could have been far worse.

Clock users said even small risks were too much. Patrizia Tavella runs the time department at the International Bureau of Weights and Measures, which keeps the world's official clock. She told Scientific American her team estimated a 30% chance of a negative leap second by 2035. Her team then asked the people who depend on the clock. "They said, 'No, even 10 percent risk is too much,'" she said.

Timekeepers say key systems weren't ready to delete a second. The bureau said critical systems were "largely unprepared" for it. It said getting ready would cost about as much as getting ready for Y2K. Peter McDowall is New Zealand's chief metrologist. He was set to cast his country's vote. Before the meeting, he said subtracting a second "is not something we've ever had to do before and are quite frankly unprepared for."

Supporters say phone networks and power grids will be safer. Setnam Shemar is a principal scientist at Britain's National Physical Laboratory. "It is a good decision overall," he told the Daily Mail. "The decision taken today reduces the risk to systems that depend on precise and continuous time synchronisation," he said, The Independent reports. He warned that a botched leap second could lead "to the failure of systems such as mobile phone networks or electricity grids." He said scientists will keep measuring the Earth's spin and keep publishing how far the clock has drifted.

But the Old System Worked, and Time Should Follow the Sun (Marek Ziebart, Paul Delaney)

Some scientists say the computer problems were overblown or fixable, and the clock should stay tied to the Earth.

One geodesist says the tech fears were overblown. Marek Ziebart is a professor of space geodesy at University College London. "We have a system in place that uses leap seconds. It works," he told CNN before the vote. He said dropping it means people "will have to check their software, redesign it, fix it."

He says human time follows the sun. Ziebart said there's "an intrinsic relationship for human beings between rotation and time." "We're driven by these periodicities of the sun rising, the sun setting," he said.

Another scientist thinks programmers could handle one second. Paul Delaney is a professor emeritus of physics and astronomy at York University in Toronto. He told CBC News that leap seconds are "a problem for an increasingly computerized, AI-oriented economy." But he asked, "Don't we still hire computer programmers to sort these sorts of things out?" He said part of him thinks "we're throwing in the towel."

And Big Tech's Needs Won Out Over Everyone Else's (Michelle Bastian)

A scholar of time says the vote bent the world's clock to fit the biggest companies.

One scholar says computers came first. Michelle Bastian is a senior lecturer in theory, culture and environment at the University of Edinburgh. In The Conversation, she wrote that the decision suggests "computing needs have been placed above the requirements of other sectors." She noted that astronomers will no longer be able to use UTC as a rough stand-in for the Earth's rotation.

She says the companies had already gone their own way. In 2008, Google spread an extra second across 20 hours on its own servers instead of following UTC. Bastian wrote that Google "invented its own form of clock time." Amazon, Google and Meta campaigned to scrap the leap second, The Independent reports. "Currently, if you are big enough it will bend to your needs," Bastian wrote.

Still, a Leap Hour Leaves the Problem for Someone Later (Jeremy Roberts, Louise Devoy, Sergei Gulyaev)

Others note the change leaves a leap hour for future generations and extra work for astronomers.

Someone will have to deal with that hour. Jeremy Roberts is a senior director at Info-Tech Research Group. He told Computerworld that letting the clock drift an hour "would presumably create a problem for our descendants." He still backed the change, because "being indecisive could cause fragmentation in standard time." Louise Devoy is a senior curator at the Royal Observatory Greenwich. She told CNN the plan leaves the leap-hour decision to future generations.

Timekeepers say that day is thousands of years away. The bureau's Tavella told CNN it would take more than 3,000 years for the clock to drift a full hour. Sergei Gulyaev is a radio astronomer at Auckland University of Technology. He called a leap hour "a reasonable option" before the vote. He said astronomers will have to track the growing gap themselves, but they're "a relatively small community."

Where This Lands

The world's timekeepers chose an unbroken atomic clock over one kept within a second of the Earth's spin. Tavella said the people who rely on the clock wouldn't accept even a 10% risk of deleting a second. Ziebart said the old system worked and kept the clock tied to the sun. Bastian says the biggest tech companies got a clock built for their needs. Roberts backs the change but says it leaves a problem for our descendants.

Sources