Timekeeping as we know it is on the verge of a major shift. Plans to retire the leap second—once slated for 2035—are now being expedited to prevent potential havoc on global tech infrastructure.
What Is a Leap Second?
A leap second is a one-second adjustment occasionally applied to Coordinated Universal Time (UTC) to keep it aligned with astronomical time, which is based on Earth's slightly irregular rotation. Since atomic clocks are extremely precise and Earth's rotation is not, the two drift apart over time.
To correct this drift, leap seconds have been inserted periodically since 1972. These adjustments ensure that civil time remains roughly in sync with the sun's position in the sky—important for everything from navigation to astronomy.
Why the Rush to Retire It?
While adding a second may sound harmless, in practice it can wreak havoc on modern technology. Computers, servers, and networks rely on precise, continuous timekeeping. An unexpected extra second can cause timestamp errors, data corruption, and system crashes.
In 2012, a leap second caused widespread outages on Reddit, Mozilla, and other major platforms. Similar disruptions occurred in 2015 and 2017. As the world becomes more dependent on interconnected digital systems, the risks posed by leap seconds have grown more serious.
The 2035 Deadline—Now Sooner
The international body responsible for timekeeping standards, the International Telecommunication Union (ITU), previously agreed to phase out leap seconds by 2035. However, recent discussions suggest the timeline may be accelerated. The goal is to prevent further disruptions to critical infrastructure, including financial markets, GPS satellites, and telecommunications networks.
Under the new proposal, leap seconds would be discontinued as early as 2026 or shortly thereafter. Instead, a yet-to-be-determined mechanism would be used to reconcile atomic time with astronomical time—possibly by allowing a larger offset to accumulate before making a single, more substantial correction.
What Comes Next?
Eliminating the leap second doesn't mean abandoning astronomical timekeeping altogether. Scientists and standards bodies are exploring alternative solutions, such as relying solely on atomic time or adjusting UTC with less frequency but larger increments.
As of 2026, the debate continues, but the direction is clear: the leap second's days are numbered. For an increasingly digital world, that's likely good news.
This article was originally reported by Jess Weatherbed for The Verge.
via The Verge