Science & Tech · Science & Environment · 12 hrs ago
Leap seconds will end under new world time rules from May 2027
The global weights and measures conference voted to end leap seconds in a change to how the world keeps time.
Since 1972, an extra second has occasionally been added to keep atomic time close to time measured by Earth's rotation, which varies slightly.
From 20 May 2027, coordinated universal time will run without further leap seconds.
The change is meant to reduce the risk of problems for computer systems, telecommunications, satellite navigation and power networks when a second is added suddenly.
People will not need to change their clocks, and Germany's radio-controlled clocks will continue to receive their time signal.
Systems that compare atomic time with Earth's rotation, including some observatories, will need to account for a growing difference.
That gap may eventually reach one hour, though experts expect this to take centuries.
The CGPM has decided to end leap seconds, with continuous Coordinated Universal Time (UTC) taking effect on 20 May 2027.
Leap seconds were added to keep atomic time aligned with time based on Earth’s rotation.
The change is intended to avoid technical problems caused by adding or removing a second suddenly.
Most people will not notice a difference, but systems that rely on the gap between atomic time and Earth’s rotation may need to adapt.
The PTB in Braunschweig says Germany’s radio clocks will not need technical changes.
- Who
- The General Conference on Weights and Measures (CGPM) decided to end leap seconds.
- What
- UTC will continue without further leap seconds from 20 May 2027.
- When
- The new rule takes effect on 20 May 2027.
- Where
- The decision was made in Versailles and applies to the global time system.
- Why
- Sudden leap seconds can cause problems for technical systems, and Earth’s rotation does not run uniformly.
This story does not have two clearly opposing sides.
The practice of adding leap seconds began.
The most recent leap second was added.
The CGPM had already decided to end the leap-second procedure.
Continuous UTC without further leap seconds is due to take effect.
- Effective date
- 20 May 2027
- Past leap seconds
- 27 had been added since 1972
- Last leap second
- End of 2016
- Radio clock signal
- DCF77, sent from Mainflingen
- Future permitted gap
- Up to one hour between atomic time and Earth’s rotation
2 sources
What people are saying
If there are no more leap seconds, this part of the transmitted code will simply remain inactive
The abolition or introduction of a leap second has no direct impact on this process