The world’s official clock just lost a second it will never get back. On Thursday, timekeepers from 69 countries voted to abolish the leap second — the fiddly one-second correction that has kept atomic clocks in step with Earth’s rotation since 1972, and crashed some of the internet’s biggest platforms along the way.
The vote, at the 28th General Conference on Weights and Measures in Versailles, France, ends a system that added 27 extra seconds to the world’s clocks over 54 years. From May 20, 2027, Coordinated Universal Time will run continuously, allowed to drift up to a full hour from Earth’s rotation before anyone touches it — a correction that likely won’t be needed for centuries.
A One-Second Fix With a Body Count
The leap second exists because Earth’s rotation is unsteady. Atomic clocks tick at an unwavering rate, but the planet speeds up and slows down with the churn of its core, oceans, and atmosphere, so every few years the timekeepers slipped an extra second into UTC — a 61-second minute — to keep the two in line. The last one came at the end of 2016.
For computers, that 61st second is a landmine. The 2012 leap second took down Reddit and LinkedIn and delayed Qantas flights; another in 2016 briefly knocked out Cloudflare. Meta called the leap second “a major source of pain” and, along with Google and Amazon, lobbied for years to kill it — the tech giants even built their own workarounds, “smearing” the extra second across hours rather than inserting it all at once, as Scientific American reported.
“After 30 years of debates, we are ready,” said Noël Dimarcq, the French timekeeping scientist who introduced the resolution. The vote wasn’t unanimous — it needed only a majority, Nature reported — but it was decisive: continuous UTC is now the plan.
The Negative Leap Second Nobody Is Ready For
The vote was really about a ghost. Since about 2016, Earth has been spinning faster than at any point in the atomic-timekeeping era — fast enough that the next correction might not add a second but remove one. A negative leap second has never happened in 54 years of the system, and as Scientific American notes, nobody has built software to survive it.
That prospect is what forced the decision years ahead of the original 2035 target set in 2022. Setnam Shemar, a principal scientist at the UK’s National Physical Laboratory, warned that checking the world’s systems for a negative leap second would be enormously costly — and some software has simply never been tested against one.
Why This Matters
For you, nothing changes on the clock: time zones stay put, daylight saving stays put, and your phone keeps showing the right time. The difference lives entirely in the machinery underneath — the data centers, phone networks, GPS satellites, power grids, and stock exchanges that depend on time flowing without sudden jumps. Those engineers were the real audience for Thursday’s vote.
And the drift is no fantasy: over the centuries, official time will slowly separate from the sun’s position in the sky, until clocks read an hour off astronomical time. As Royal Observatory Greenwich time curator Emily Akkermans told New Scientist, the eventual effect will be “like living on daylight saving time” — permanently. Your great-great-grandchildren’s problem, not yours.
The same Versailles meeting also began work on an even wilder frontier: a lunar time standard and a redefinition of the second itself. Killing the leap second was the easy vote.
Meanwhile in Tech News: read about Anthropic’s $11.6 billion cloud deal with Akamai, and the FBI’s second takedown of Flax Typhoon hacking tools.
