BIPM to vote on abolishing leap second system

The International Bureau of Weights and Measures (BIPM) is set to vote in October on a proposal to abolish the leap second system. This move comes as scientists observe an acceleration in Earth's rotation, which could necessitate a “negative leap second”—subtracting a second rather than adding one—for the first time by 2035.

Experts warn that most global computer systems, network time protocols, and critical infrastructures like telecommunications, power grids, and satellite navigation are not designed to handle time moving backward. Such a discrepancy could trigger widespread technical failures, drawing comparisons to a modern-day Y2K crisis. Previous leap second adjustments have already caused service disruptions for major platforms including Reddit, LinkedIn, and Cloudflare.

The proposed new regulation would move the timeline for abolition forward to May 20, 2027. It would also significantly expand the allowable discrepancy between Coordinated Universal Time (UTC) and UT1 from 0.9 seconds to up to one hour. This shift would likely replace leap seconds with “leap hours,” occurring only once the error accumulates to a full hour. Given current rotation speeds, it is estimated that such an adjustment would only be required once every thousand years.