BIPM to cease adding leap seconds to UTC by 2035, ensuring continuous time scale

Leap Seconds to End by 2035

The 28th General Conference on Weights and Measures (CGPM) has passed Resolution 5, which mandates the cessation of adding leap seconds to Coordinated Universal Time (UTC) by 2035. This decision follows previous resolutions from 2018 and 2022, which confirmed UTC as the international reference time scale and acknowledged the need for its future development.

Ensuring Continuity for Critical Systems

The primary motivation for this change is to ensure the continuity of UTC. Industrial users and critical national infrastructures, such as transportation, energy distribution, telecommunication, and space projects, require a time scale that is not subject to future adjustments. The current system of leap seconds, which periodically adds a second to UTC to keep it aligned with Earth's rotation (UT1), introduces complexities for these systems.

Impact on Time Synchronization

With the removal of leap seconds, the maximum difference between UT1 and UTC will be allowed to increase. This ensures UTC's continuity for at least a century. For applications that require knowledge of the Earth's rotational position, information on the UT1-UTC difference will continue to be available through Global Navigation Satellite Services (GNSS) and services provided by the International Earth Rotation and Reference Systems Service (IERS) and National Metrology Institutes (NMIs).

Background and Future Steps

UTC is produced by the International Bureau of Weights and Measures (BIPM) and maintains the same rate as International Atomic Time (TAI), differing only by an integral number of seconds. The International Telecommunication Union Radiocommunication Sector (ITU-R) is studying updates for transmitting the UT1-UTC difference by radio stations, indicating ongoing efforts to manage the transition and provide necessary data to users.