Since 1972, 27 such seconds have been added to Coordinated Universal Time (UTC) in order to synchronize atomic clocks with the Earth's rotation. Now the difference between UTC and astronomical time UT1 will be able to reach a whole hour — 3600 seconds — before a correction is required.
Previously the limit was only 0,9 seconds. When the discrepancy approached this value, an additional second was introduced, most often at the end of June or December. The last time this happened was in 2016.
The reason for the abandonment is technical problems. Digital systems, from exchanges to navigation and data centers, handle sudden jumps in time poorly. Engineers call the negative leap second, which could have been introduced because of the acceleration of the Earth's rotation since the mid-2010s, a "mini-Y2K."
The Earth began to rotate faster, and the risk of such a correction by 2035 was estimated at 30 percent. Instead of seconds, they now plan to add an hour, but, according to forecasts, this will not be needed until at least a thousand years from now.
The decision was adopted by a majority vote after lengthy debates. Representatives of 69 countries supported the transition to a continuous UTC scale. As the metrologist Noël Dimarcq put it, this is a "historic moment" and a "decisive step" for the international time standard.
What does this mean for ordinary clocks and time zones? Nothing radical in the coming decades — atomic time will simply stop following the Sun so strictly. And exactly how this will affect precise scientific observations and software, only time will tell.
