Leap Second Officially Abolished by BIPM

The International Bureau of Weights and Measurements (BIPM) has officially killed the leap second, announcing it will halt issuance in May 2027. Introduced in 1972 to bridge the gap between atomic clock time (UTC) and astronomically measured Universal Time (UT1), 32 leap seconds have been inserted over the past five decades as Earth's rotation gradually slows — primarily due to tidal friction from the moon.

For most people, a second here or there sounds trivial. For tech infrastructure, it's anything but. Every leap second forces engineers to reconcile systems running on UTC, and not all of them do it cleanly. Qantas's booking system crashed in 2012 thanks to a leap second. Google and Meta long adopted a workaround — "smearing" the extra second across a full day in tiny increments — but this patchwork fix isn't universal.

The final nail came from an unexpected direction: climate change. Melting polar ice has shifted Earth's gravity distribution enough to actually speed up the planet's rotation in recent years. A 2024 Nature study warned a negative leap second — something never before attempted and never tested on live systems — could have been required as early as 2029. NIST fellow Judah Levine put it plainly: "The concern was that the negative leap second would be much more serious because its effects had never been tested." BIPM concluded the risk wasn't worth it.