General Conference on Weights and Measures to abolish leap seconds in 2027

The General Conference on Weights and Measures (CGPM) has voted to abolish the leap second, effective May 20, 2027. The decision, reached during the 28th meeting in Versailles, France, aims to prevent technical disruptions in digital infrastructure.

Since 1972, leap seconds have been used to synchronize Coordinated Universal Time (UTC), based on atomic clocks, with astronomical time (UT1), which is based on the Earth's irregular rotation. While these adjustments have historically involved adding a second, recent changes in Earth's rotation speed have raised the risk of a “negative leap second”—subtracting a second—which could cause significant errors in computer systems, telecommunications, and financial markets.

Under the new resolution, the maximum allowed discrepancy between atomic time and astronomical time will increase from 0.9 seconds to 3,600 seconds (one hour). Experts suggest that a full hour correction may not be necessary for hundreds or even thousands of years, providing long-term stability for global technological networks.