Weights and Measures Conference to Vote on Continuous UTC From 2027 as Negative Leap-Second Risk Hits 30%
Updated
Updated · Computerworld · Sep 9
Weights and Measures Conference to Vote on Continuous UTC From 2027 as Negative Leap-Second Risk Hits 30%
1 articles · Updated · Computerworld · Sep 9
Summary
October’s General Conference on Weights and Measures will decide whether UTC should run continuously from May 20, 2027, ending leap-second adjustments and allowing UTC and Earth-rotation time to drift apart by as much as one hour.
A 2025 expert workshop put the chance of needing a negative leap second at 30% by 2035, and the conference said subtracting a second poses high risk because critical systems were never built for that scenario.
Analysts said a negative leap second could break assumptions in databases, authentication, trading, logging and distributed systems, producing widespread inconsistencies even without a single headline-grabbing outage.
Past clock glitches underscore the concern: a 2012 positive leap second disrupted Reddit, LinkedIn and Qantas booking systems, while a separate timekeeping issue hit Australia’s Telstra network last month.
Supporters call continuous UTC the biggest civil-timekeeping change since leap seconds were adopted in 1972, arguing it avoids systemic digital risk now even if future generations must manage a wider UTC-UT1 gap.