Leap seconds, used for a half century to synchronize the Earth’s rotation with atomic clocks, are being phased out. That’s a boon for tech giants that are worried about the adjustment’s technical risks.
Timekeeping authorities from around the world voted Friday at a meeting of the Bureau International des Poids et Mesures (BIPM) to stop using the temporal tweak.
“The…introduction of leap seconds creates discontinuities that risk causing serious malfunctions in critical digital infrastructure,” including satellite navigation systems, telecommunications and energy transmission, BIPM said of its reasoning for the move.
The change will take effect no later than 2035, though it’s possible the group could phase it in sooner. The new policy is designed to last at least a century.
Timekeeping with this level of precision may sound like an arcane scientific domain, but it actually matters a lot in our digital age, in which computers must constantly track tasks and make sure actions take place in the right sequence. Ticking digital clocks are a foundation for everything we do online.
In August, Facebook pushed for an end to the leap second, warning the transition could have “devastating effect on the software relying on timers or schedulers.” It’s not alone: a committee associated with BIPM surveyed measurement, scientific and technology experts and found the same view.
It’s not an idle worry. The leap second change triggered a massive Reddit outage in 2012, as well as related problems at Mozilla, LinkedIn, Yelp and airline booking service Amadeus. In 2017, a leap second glitch at Cloudflare knocked a fraction of the network infrastructure company’s customers’ servers offline. Cloudflare’s software, comparing two clocks, calculated that time had gone backward but couldn’t properly handle that result.
Earlier leap seconds have been added to compensate for the Earth’s slowing rotation, but there’s evidence the rate is now speeding up. That would mean a leap second would have to be removed, and that’s never been tried.
Although the leap second no longer will routinely be added when Earth time disagrees with Coordinated Universal Time (UTC), the BIPM vote leaves the door open for adjustments. It recommended forming a policy for adjusting clocks at some as yet unspecified time gap.