Global timekeeping authorities are set to vote next month on scrapping leap seconds, the periodic one-second adjustments used since 1972 to keep Coordinated Universal Time (UTC) aligned with the Earth's rotation. The move is driven by growing concern over the possibility of a "negative" leap second, something never attempted before, which could seriously disrupt computer systems, telecommunications, power grids and satellite navigation because most digital infrastructure assumes seconds are only ever added, never removed.

Under the draft resolution, UTC would become continuous from 20 May 2027, allowing it to drift from Earth-rotation-based time (UT1) by up to an hour, far beyond the current 0.9-second tolerance. The change follows a slight speeding up of Earth's rotation, which experts estimate gives a 30 percent chance of requiring a negative leap second by 2035. Setnam Shemar of the UK's National Physical Laboratory said the vote, expected in October at the General Conference on Weights and Measures, is likely to pass given broad international support, and would remove the need for further adjustments for at least a thousand years.