The Leap Second Is Dead: Why the World's Timekeepers Voted to Kill It

Your minute has never lasted 61 seconds — and thanks to a vote taken outside Paris this week, it never will again. On October 15, 2026, member states of the General Conference on Weights and Measures (CGPM) voted to abolish the leap second, the occasional extra tick that timekeepers have been slipping into the world's clocks since 1972 to keep atomic time in step with Earth's rotation. Experts are calling it the biggest shake-up of global timekeeping in generations.

Most of us never noticed the leap second. But behind the scenes, that single extra second has been a thorn in the side of everyone who runs the modern world: the operators of satellite navigation, stock exchanges, power grids and the vast server farms that keep the internet alive. Now the compromise that created it has been thrown out — and replaced with something far stranger.

What a leap second actually is

There are two ways to tell the time. One is astronomical: Universal Time 1 (UT1), based on how long Earth takes to rotate — the time told by the sun's position in the sky. The other is atomic: Coordinated Universal Time (UTC), ticked off by ultra-precise atomic clocks that count the vibrations of cesium-133 atoms — 9,192,631,770 oscillations per second, as physicists at institutions like the Smithsonian like to remind us.

The trouble is that Earth is a lousy clock. Its rotation wobbles and drifts, so the two time scales slowly fall out of sync. Since 1972, timekeepers have bridged the gap by adding 27 leap seconds to UTC — moments when the world's clocks effectively pause for one second so the planet can catch up. The rule was to keep the two scales within 0.9 seconds of each other.

Why the timekeepers just killed it

Two things forced the issue. First, the rogue seconds have repeatedly disrupted computing systems — glitches and outages have followed leap-second insertions at major tech companies, which is why the outcome of the vote, as headlines noted, favours big tech. Second, something unexpected happened to the planet itself: Earth began spinning slightly faster. That raised the alarming prospect of the first-ever negative leap second — deleting a second from the world's clocks, something for which, as The Times reported, there is no large-scale precedent. Experts feared that skipping a second could cause havoc with computer systems, telecommunications networks and electricity grids.

So the delegates at the CGPM's 28th meeting in Versailles voted — by majority — to stop the practice entirely. "This decision will ensure the continuity and relevance of UTC for centuries to come," said Georgette Macdonald, director general of Canada's National Research Council metrology centre, which backed the resolution. Noël Dimarcq, the metrologist at the Côte d'Azur Observatory who formally introduced it, called it "a historical moment, a decisive step for UTC."

Enter the leap hour

The replacement is beautifully simple: instead of fussing over fractions of a second, atomic time will now be allowed to drift away from astronomical time, up to a maximum difference of one hour — 3,600 seconds. When that gap is eventually reached, a single "leap hour" would be inserted. Scientists estimate that won't be needed for centuries, or even millennia. As Christian Bizouard, director of the International Earth Rotation Service's Earth Orientation Center, put it: "What we are doing is pushing back the decision."

The change takes effect on May 20, 2027 — World Metrology Day — giving industry about a year and a half to adapt.

What actually changes for you

Almost nothing. Your phone, your watch and your wall clock will keep working exactly as before. The shift happens deep inside the infrastructure: satellite navigation, high-frequency trading and telecom networks get a time scale that never jumps unexpectedly. The ancient link between the clock on your wall and the turning of the planet is quietly loosened — and the problem is handed to a generation thousands of years from now.

For more big-science stories, see our explainers on the black hole that played a treble clef across the stars, Artemis II's 814GB data release and Yuezhuornis, the Jurassic bird that preferred running.

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