The body responsible for global timekeeping said scientists and government officials gathered at a conference in France on Friday had voted to abolish leap seconds by 2035. As in leap years, leap seconds have been added to clocks periodically over the past half century to compensate for the difference between precise atomic time and the slower rotation of the Earth.

While leap seconds are invisible to most people, they can cause problems in a number of systems that require a precise and uninterrupted flow of time, such as satellite navigation, software, telecommunications, commerce, and even space travel. This caused a headache for the International Bureau of Weights and Measures (BIPM), which is responsible for Coordinated Universal Time (UTC), the agreed international standard by which the world sets its clocks.

The decision to end the addition of leap seconds by 2035 was adopted by the BIPM’s 59 member states and others at the General Conference on Weights and Measures, held approximately every four years at the Palace of Versailles, west of Paris. Patricia Tavella, BIPM’s head of time, told AFP the “historic solution” would allow “a continuous flow of seconds without interruptions caused by the already irregular leap seconds”.

“The change will go into effect in 2035 or before,” he said by email.

According to him, Russia voted against the “unprincipled” decision, but only because Moscow wanted to push the decision’s entry into force to 2040. Other countries have called for a faster time frame like 2025 or 2030, so 2035 is the “best compromise” he said. Tavella stressed that “the connection between UTC and the Earth’s rotation is not lost.” “Nothing will change” for the public, he added.

Is it a minute now?

Seconds have long been measured by astronomers analyzing the Earth’s rotation, but the advent of atomic clocks, which use the frequency of atoms as a tick-tock mechanism, ushered in the era of much more accurate time measurement. But the slightly slower rotation of the Earth means the two times are out of sync.

To fill this gap, leap seconds were introduced in 1972 and have since been added at irregular intervals of 27 seconds, most recently in 2016. As part of the offer, leap seconds will be added as usual for now. But by 2035, the difference between atomic and astronomical time could rise to more than a second, physicist Judah Levin of the US National Institute of Standards and Technology told AFP.

“The greater value has yet to be determined,” said Levin, who has helped prepare the decision with Tavella for years. According to the resolution, negotiations will be held to find a proposal by 2035 to determine this value and how it will be used. Levin said it’s important to maintain UTC time at BIPM as it is managed by a “worldwide community effort”.

A potential competitor to UTC, which is controlled by atomic clocks, GPS time is controlled “without worldwide control” by the US military, Levin said. One possible solution to the problem would be the discrepancy between Earth’s rotation and atomic time increasing to one minute. It’s hard to say exactly how long this will take, but Levin estimated between 50 and 100 years. Instead of adding a leap minute to the clock, Levine suggested a “various spotting” in which the last minute of the day takes two minutes.

“The clock is ticking, but it never stops,” he said.