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A decision has been made to discontinue the leap second system, which has been used for decades to maintain standard time around the world.
A decision has been made to discontinue the leap second system, which has been used for decades to maintain standard time around the world. At a conference held under the auspices of the International Bureau of Weights and Measures, 69 member countries unanimously approved ending the current leap second system from May 2027. The aim is to simplify the process of maintaining global standard time and protect computer systems, internet servers, communication networks, and navigation systems from potential technical failures.
The practice of adding leap seconds began in 1972. Since then, a total of 27 additional seconds have been added to Coordinated Universal Time (UTC). The primary purpose of this procedure was to limit the difference between time measured by atomic clocks and the Earth's natural rotation. Because the Earth's rotation speed is not constant, the difference between these two time scales gradually changes.
Coordinated Universal Time (UTC) is used as the global standard for timekeeping and is calculated using highly precise atomic clocks. Meanwhile, the length of day and night is determined by the Earth's rotation. To keep the difference between these two measurements within a certain limit, an extra second has periodically been added to global clocks when necessary. Although seemingly minor, this adjustment has created several complex challenges for modern digital systems.
Under the decision, the new system will take effect on May 20, 2027. The difference between global standard time and the Earth's rotation will be allowed to increase to a maximum of one hour. This change is expected to eliminate the need to add leap seconds for at least several centuries. In recent years, changes in the Earth's rotation speed have raised concerns among timekeeping experts. There were fears that if a negative leap second became necessary in the future — meaning that one second would have to be removed from clocks — systems not designed to handle such a change could experience serious malfunctions.
In response to these risks, an agreement was reached to phase out leap seconds. The new approach is intended to maintain continuous global standard time. Atomic clocks will continue to provide the basis for timekeeping, while the difference between atomic time and the Earth's rotation will be allowed to accumulate rather than being immediately corrected by adding or removing a second. Once the difference approaches one hour, experts will consider how to adjust it in the future. According to estimates, it could take several centuries for the difference to reach that threshold.
A leap second is an additional second inserted into the timekeeping system to keep clock time aligned with the Earth's rotation.
In simple terms:
Why was it necessary?
Atomic clocks measure time with extraordinary precision, but the Earth's rotation varies slightly in speed. Leap seconds were used to keep the difference between these two time measurements within an acceptable limit.
Example: Suppose a clock shows 11:59:59 p.m. normally, the next moment would be midnight. However, when a leap second is inserted, the clock first displays 11:59:60 p.m. before advancing to midnight.
The sudden addition of an extra second can cause technical problems for internet servers, computers, telecommunications systems, and navigation technologies. For this reason, the international community has decided to phase out leap seconds to make global timekeeping more stable and reliable. It is important to note that a leap second and a leap year are two different things. Ending the leap second system will not affect the calendar system that gives February 29 days during a leap year.
