Time is a-changin’: say goodbye to the leap second

Critical digital infrastructure will no longer face unpredictable disruptions from leap second adjustments.

The International Bureau of Weights and Measures (BIPM) has voted to eliminate the leap second, an occasional adjustment made to synchronize atomic time with Earth's rotation. This change, initially slated for 2035, will now take effect on May 20th of next year, World Metrology Day. The decision was accelerated due to the potential need to subtract time from the atomic clock to match Earth's rotation, a complex procedure that could disrupt critical digital infrastructure. Past leap second additions have caused outages for major tech platforms like Reddit and LinkedIn. Major tech companies including Meta, Google, Microsoft, and Amazon have advocated for the removal of leap seconds. Instead of leap seconds, timekeepers will use "leap hours," allowing atomic and astronomical time to diverge for approximately 3,000 years before a full hour adjustment is needed.

The expedited retirement of the leap second signals a pragmatic shift in global timekeeping, prioritizing the stability of digital infrastructure over the precise alignment of atomic and astronomical time. The decision by BIPM, supported by major tech players, reflects a growing concern that the complex and infrequent nature of leap second adjustments poses an unacceptable risk to the interconnected digital world, a risk that the advent of negative leap seconds could exacerbate.

This move effectively standardizes timekeeping for the digital age, sidestepping potential cascading failures that have previously impacted major platforms. The adoption of "leap hours" is a strategic acknowledgment that gradual drift is manageable, whereas the abruptness of leap seconds is not, paving the way for more predictable system operations and potentially reducing the need for complex, real-time synchronization protocols in critical applications.