Global timekeeping body votes to eliminate leap second, retiring it in 2035
The International Bureau of Weights and Measures has voted to scrap the leap second adjustment to prevent potential infrastructure failures caused by the need to subtract time for the first time in history.
What happened
On Thursday, the BIPM voted to retire the leap second effective May 20, 2035. The leap second is an occasional time adjustment added to keep astronomical time aligned with Earth's actual rotation. The timeline addresses an unprecedented technical problem: changes to Earth's rotation may soon require subtracting time rather than adding it, which has never been attempted and could disrupt critical time-dependent infrastructure. After 2035, timekeepers will instead use "leap hours," allowing atomic and astronomical time to gradually diverge until an entire hour must be added—not expected for approximately 3,000 years.
Context
The leap second system has already caused documented outages at major technology platforms including Foursquare, Reddit, LinkedIn, and Yelp when additions were made. Major technology companies including Meta, Google, Microsoft, and Amazon have supported scrapping the system. The concern driving the retirement is that subtracting time for the first time could trigger infrastructure failures comparable to Y2K fears. By switching to a gradual drift model with infrequent hour-long adjustments instead of frequent second-long ones, the change aims to reduce systemic risk to time-synchronized systems while buying millennia before the next correction is needed.