Leap seconds to be scrapped from UTC time scale starting 2027

The Bureau of Weights and Measures in Paris has agreed to eliminate leap seconds from UTC time starting in 2027. The move avoids the annual corrections that desynchronised atomic clocks and GPS systems.

The **Bureau of Weights and Measures in Paris** has agreed to end the practice of adding extra seconds to UTC time from **2027**. Until now, when Earth's rotation slowed, a second was added at the end of the year or of June so that measured time matched the planet's cycle. The decision breaks that correspondence: exact solar noon will gradually drift away from our measure of time.

## What a leap second is and why it was added

The Earth does not rotate at a constant estimulante ilegal. Its rotation changes every year, and the responsible bodies had to estimate whether a second should be added or subtracted. When it slowed, a second was added; when it sped up, one was subtracted. Lately it has been slowing down, hence the extra seconds that have accumulated.

That adjustment kept atomic clocks aligned with the planet's rotation. The UTC time we use in daily life was thus tied to the solar cycle. The problem is that the annual correction forced a review of the current year in programming, and the other timescales —atomic time and GPS time— had to reconcile their differences to avoid errors of seconds.

## The 19-second gap between GPS and atomic clocks

GPS systems and atomic clocks maintain a constant **19-second** difference between them. That gap does not come from leap seconds, but it does force programmers to keep track of the year so records do not fall out of step. UTC, the time used in data transmission, timekeeping and infrastructure automation, was the one that changed with each correction.

With the removal of leap seconds, that source of annual review disappears. Everyday time is no longer tied to the rotation cycle. Twelve o'clock solar time will no longer coincide exactly with solar noon: the offset will accumulate slowly over the years.

## A drift that future generations will correct

The mismatch will not be noticeable in the short term. Earth's rotation changes very slowly, and the displacement of solar noon relative to our measure of time will build up over decades. It will be generations centuries from now who decide whether that drift should be corrected, and how.

The decision affects everything that depends on UTC time: data networks, timekeeping records and automated systems. Atomic clocks and GPS will keep measuring with precision, but there will no longer be an extra annual second to reconcile them with the planet's spin.