BIPM Adopts Leap Hour, Ending Leap Seconds for 69 Nations by 2027
Updated
Updated · CNN · Oct 15
BIPM Adopts Leap Hour, Ending Leap Seconds for 69 Nations by 2027
3 articles · Updated · CNN · Oct 15
Summary
Sixty-nine nations approved a BIPM resolution in France to stop using leap seconds and shift official timekeeping to a “leap hour” framework from 2027.
The change aims to protect telecoms, power grids, trading systems and cloud networks from failures tied to irregular 61- or 59-second minutes, especially the first-ever possible negative leap second.
Leap seconds have been inserted 27 times since 1972 to keep atomic UTC aligned with Earth’s uneven rotation, but past adjustments triggered outages at Reddit, LinkedIn, Qantas and Cloudflare.
Under the new system, atomic time can drift from astronomical time until the gap reaches 3,600 seconds—about one hour—a threshold experts say would take more than 3,000 years to hit.
The vote severs a centuries-old link between civil time and Earth’s rotation, prioritizing machine-stable atomic clocks over the Greenwich-based astronomical standard.