World Timekeepers Vote to Retire the Leap Second

The leap second is on its way out. The international bodies that govern official time have decided to stop inserting the occasional extra second into clocks, ending a practice that has been in place since 1972.

The reason goes back to how time is measured. Atomic clocks keep time with extraordinary steadiness, while Earth's rotation slows slightly and unevenly because of tides and other forces. To keep civil time roughly in line with the sun, engineers added leap seconds, usually at the end of June or December. Each one forces a clock to read 23:59:60 before rolling over to midnight.

That rare moment has caused trouble for decades. Computer systems, telecom networks, financial trading platforms and satellite navigation have all stumbled when a minute suddenly has 61 seconds. Some systems repeated a second, stalled or crashed, and engineers built workarounds such as "leap smearing," which spreads the extra second across several hours.

The new decision favors simplicity. Without leap seconds, clock time will gradually drift away from solar noon, and over centuries the gap would become noticeable. Supporters argue that is a fair trade for predictable software and networks. Critics, including some astronomers and navigators, say it weakens a long-standing link between clock time and the sky.

Background matters here. In November 2022, the General Conference on Weights and Measures voted to phase out leap seconds by 2035 and asked for further work on the details. The announcement that the decision is now settled is the step that turns that plan into a firm commitment. The source material did not include the exact final cutoff or how much drift is acceptable, so readers who need those specifics should check the official resolution.