Leap Seconds Abolished as Timekeepers Adopt a New Global Time Standard

Leap seconds will be abolished immediately, rather than in 2035, under a new decision by the world’s leading metrologists.

The adjustment, which used to add or remove one second roughly once every 1.5 years, will now wait until a difference of one hour needs to be corrected.

Why leap seconds were used

Leap seconds helped align time based on the Sun’s position in the sky with Coordinated Universal Time (UTC), the more stable time standard based on atomic clocks. Earth’s natural rotation is irregular, whereas atomic clocks provide a highly consistent measure of time.

However, leap seconds created problems for timekeepers. The sudden one-second changes disrupted computer systems and caused discrepancies between clocks when they were introduced.

Replacing the current system with a one-hour correction for every 3,600-second difference between Earth time and atomic time is unlikely to be necessary for thousands of years. The change effectively leaves the problem for future generations.

Leap seconds have been abolished. Long live leap time?

International vote changes the future of UTC

Members of the General Conference on Weights and Measures (CGPM) voted in favor of the resolution during its 28th session, held outside Paris on 15 October.

“This decision ensures the continuity and relevance of UTC for centuries to come,” said Georgette McDonald, director of the National Research Council of Canada’s Center for Metrology in Halifax. Canada supported the resolution, which was not unanimous but required only a majority to pass.

“This is a historic moment and a decisive step for UTC,” said Noël Dimarque, a metrologist at the Observatory of the Côte d’Azur in Nice, France, who formally introduced the resolution.

“We now have an international reference time scale. It will continue for thousands of years to come,” he added.

What the end of leap seconds means