Starting in 2035, no extra seconds will be added to synchronize clocks with astronomical time
At the General Conference on Weights and Measures, it was decided, starting at least in 2035, to suspend the periodic synchronization of the world's reference atomic clocks with Earth's astronomical time.
This is due to the lack of uniformity in the Earth's rotation; astronomical clocks are slightly behind reference clocks , and to synchronize the exact time, starting in 1972, atomic clocks were suspended by one second every few years, as soon as the difference between the reference and astronomical clock time reached 0,9 seconds (the last such correction was 8 years ago).
Now, starting in 2035, synchronization will cease and the difference between Coordinated Universal Time (UTC) and astronomical time (UT1, mean solar time) will accumulate.
The issue of halting the addition of an extra second has been discussed at the International Bureau of Weights and Measures since 2005, but the decision has been repeatedly postponed . In the long term, the Earth's rotation gradually slows due to the Moon's gravitational influence, and the intervals between synchronizations decrease over time. For example, if this dynamic were to continue for 2000 years, a new second would have to be added every month.
Deviations in the Earth's rotation parameters are random in nature and their change, observed in recent years, may lead to the need not to add, but to subtract an extra second.
As an alternative to second-by-second synchronization, the possibility of synchronization with cumulative changes of one minute or one hour is being considered, which would require time correction every few centuries. A final decision on the additional synchronization method is expected before 2026.
The decision to discontinue one-second synchronization was due to numerous software system failures related to the appearance of 61 seconds within one of the minutes during synchronization. In 2012, this synchronization caused massive failures in server systems configured to synchronize the exact time using the NTP protocol.
Due to the unwillingness to handle the extra second, some systems got stuck in a loop and began consuming unnecessary CPU resources. In the next synchronization, which took place in 2015, it seemed that the unfortunate experience of the past had been taken into account, but a bug was found in the Linux kernel during preliminary testing (fixed before the synchronization) that caused some timers to run a second earlier than intended.
Although Earth's rotation is slowing down in the long term as a result of the Moon's pull, an acceleration since 2020 has also made the problem more pressing because, for the first time, it may be necessary to remove a leap second, rather than add one. UTC has only had to slow down by one second to wait for Earth, not skip ahead to catch up. "It's described as a Y2K problem because it's something we've never had to deal with before," says Donley, referring to the computer errors that were expected to occur in the early 2000s.
Since most public NTP servers continue to provide an extra second as is , without diluting it over a series of intervals, each synchronization of the reference clock is perceived as an unpredictable emergency (in the time elapsed since the last synchronization, they manage to forget about the problem and implement code that does not take into account the feature in question).
Problems also arise in financial and industrial systems, which require precise tracking of work process times. It's worth noting that errors associated with an extra second appear not only during synchronization but also at other times. For example, a bug in the code meant to correct the extra second in GPSD caused a time shift of 1024 weeks in October 2021. It's difficult to imagine what anomalies not adding, but subtracting, a single second can lead to.
Interestingly, synchronization termination has a drawback, which can affect the operation of systems designed for the same UTC and UT1 times. Problems can arise in astronomical (for example, when adjusting telescopes) and satellite systems.
Source: https://www.nature.com/