Timekeepers to Vote on Ending Leap Second by 2027
Representatives of the 69 member states of the International Bureau of Weights and Measures (BIPM) are meeting Thursday in Versailles, outside Paris, to debate and vote on a resolution to scrap the leap second by 2027. Al Jazeera The proposal under discussion would take effect in May 2027. CNN
Since 1972, timekeepers have added a leap second every few years to keep clocks in line with Earth's rotation. Coordinated Universal Time (UTC), the global time standard based on high-precision atomic clocks, is obtained from International Atomic Time by inserting leap seconds on the advice of the International Earth Rotation and Reference Systems Service to maintain approximate agreement with time derived from Earth's rotation.
The first leap second was added in 1972. There have been 27 in total, the most recent on December 31, 2016, and they occur at the end of June or the end of December.
Pressure to end the practice comes from financial markets and data centres that rely on precise timing down to milliseconds and find the extra second difficult to handle. In 2012, the addition of a leap second crashed LinkedIn and Reddit and disrupted Qantas ticket bookings. The 2022 resolution that opened the path to abolition said the introduction of leap seconds creates discontinuities that risk causing serious malfunctions in critical digital infrastructure. BIPM
In 2022, the BIPM voted to scrap the leap second by 2035. Russia sought to move that date to 2040 because it incorporates leap seconds directly into its GLONASS satellite-navigation system.
If adopted, UTC would become a (quasi) continuous time scale, eliminating the discontinuities introduced by the leap second. BIPM The International Earth Rotation and Reference Systems Service announced in July 2026 that no leap second will be introduced at the end of December 2026. Experts have said timekeepers may soon need to subtract rather than add a second, an action known as a negative leap second, and meeting documents also list discussion of redefining the second using optical instead of microwave standards for 2035 or later.
