Leap seconds introduced (1972)
Coordinated Universal Time adopted leap seconds in 1972 to stay within one second of Earth's rotational time, UT1. Since then, 27 leap seconds have been inserted at irregular intervals, most recently on December 31, 2016.
Atomic time and solar time held together within a second, preserving the link between scientific clocks and the position of the Sun in the sky.
The irregular insertions, announced only months ahead, became a recurring maintenance burden for data centers, satellite systems, and financial networks.
The 2026 vote dismantles the exact system built in 1972, replacing a seconds-level alignment with an hour-level tolerance.
