---
title: "Leap Seconds Are Being Abolished: BIPM Accelerates Abandonment of the System to Prevent Global Infrastructure Failure"
description: "The BIPM has voted to abolish leap seconds, with the decision taking effect on May 20, 2027. The move is driven by the risk of infrastructure failures if subtracting seconds becomes necessary."
date: 2026-10-17T00:23:33.641Z
lang: en
url: https://xab.info/en/posts/leap-seconds-abolished-bipm-2027
tags: [leap-seconds, bipm, time-keeping, metrology, infrastructure]
author: "Alexander Buran"
publisher: "XAB.info"
---

# Leap Seconds Are Being Abolished: BIPM Accelerates Abandonment of the System to Prevent Global Infrastructure Failure

![Vintage pocket watch hanging on a chain against a blurred autumn background](https://xab.info/media/2026/10/17/visokosnye-sekundy-resheno-otmenit-bipm/visokosnye-sekundy-resheno-otmenit-bipm-1.webp)

## Key Points

- The BIPM voted to abolish leap seconds, taking effect on May 20, 2027 — earlier than the 2022 target of 'by 2035'.
- The acceleration is due to the risk of having to subtract seconds from atomic time because of changing Earth rotation, an unprecedented scenario threatening infrastructure.
- Past leap seconds caused outages on Foursquare, Reddit, LinkedIn, and Yelp; the abolition is supported by Meta, Google, Microsoft, and Amazon.
- Leap seconds will be replaced by a 'leap hour' system, where atomic and astronomical time diverge by an hour only after roughly 3,000 years.

The International Bureau of Weights and Measures (BIPM) has voted in favor of the complete abolition of leap seconds — a mechanism that for decades has kept reference atomic time synchronized with the Earth's real, irregular rotation. The decision to abolish them will take effect on May 20, 2027, World Metrology Day. This is significantly earlier than the timeline set in 2022, when BIPM participants agreed to phase out leap seconds "by 2035 or earlier." According to the bureau, this acceleration is driven not by administrative reasons, but by technical factors related to the changing nature of the planet's rotation.

### What Is a Leap Second and Why It Existed

Atomic clocks, which form the foundation of modern timekeeping, tick with extreme precision. However, the Earth's rotation around its axis is not strictly uniform: it constantly slows down and speeds up due to tidal forces, mass redistribution, and other factors. To prevent atomic time from falling behind astronomical time, an extra leap second has been periodically added since 1972, usually at the end of June or December. Throughout the history of this mechanism, 27 such seconds have been added, and none have ever been subtracted.

### Why the Decision Was Made Ahead of Schedule

The key reason for accelerating the phase-out is an unprecedented scenario: changes in the Earth's rotation patterns mean that in the near future, it may become necessary not to add, but to subtract seconds to maintain synchronization between atomic and astronomical time. Such an operation has never been performed in the history of metrology, and BIPM experts fear that a "negative leap second" could trigger severe disruptions in critical infrastructure dependent on precise timing synchronization — from financial systems and telecommunications to power grids and navigation.

### Failures Have Already Happened: Real-World Experience

The bureau's fears are not purely theoretical. Even standard, "positive" leap seconds have previously caused outages on major internet platforms: disruptions were reported on Foursquare, Reddit, LinkedIn, Yelp, and several other services whose systems were not prepared for days being one second longer. This exact experience became one of the main arguments for abandoning a fragile mechanism that embeds a potential single point of failure into global infrastructure.

### What Will Replace Leap Seconds

The decision to abolish them has been supported by major technology companies whose systems are most sensitive to time anomalies, including Meta, Google, Microsoft, and Amazon. Instead of periodic second adjustments, it has been proposed to transition to so-called leap hours: atomic and astronomical time will gradually drift apart until the accumulated difference reaches a full hour. According to specialists' forecasts, this will not happen for at least three thousand years, effectively removing the risk of frequent synchronization interventions from global infrastructure.

### Timelines and Significance of the Decision

Formally, the BIPM decision takes effect on May 20, 2027, but practical implementation will require approval from the International Earth Rotation and Reference Systems Service (IERS), which directly announces the introduction of leap seconds, as well as software and standards updates by critical infrastructure operators. Essentially, the abolition of leap seconds represents a transition from a reactive model — where the time system is adjusted retroactively — to a predictable and stable one, reducing systemic risks for the digital services upon which a significant part of the global economy currently relies.

## Fact-Check & Sources

- [Високосные секунды решено отменить — чтоб интернет не сломался window-new](https://3dnews.ru/1150058/visokosnie-sekundi-resheno-otmenit-chtob-internet-ne-slomalsya) - Primary source: BIPM vote, implementation date May 20, 2027, acceleration relative to the 2022 target ('by 2035'), risk of a 'negative' leap second, outages on Foursquare/Reddit/LinkedIn/Yelp, support from Meta/Google/Microsoft/Amazon, transition to leap hours (~3,000 years).
- [«Високосные секунды» задумали заменить «високосным часом» — так удобнее](https://3dnews.ru/1148227/visokosnie-sekundi-zadumali-zamenit-visokosnim-chasom-tak-udobnee) - Supplementary material confirms the concept of replacing leap seconds with a 'leap hour' and the risk of failures in high-precision global coordination systems.

## FAQ

### When does the decision to abolish leap seconds take effect?

The BIPM decision to abolish leap seconds takes effect on May 20, 2027, World Metrology Day.

### Why was the decision made earlier than planned?

In 2022, BIPM participants agreed to phase out leap seconds by 2035 or earlier. The timeline was accelerated due to the risk that changing Earth rotation could require subtracting rather than adding seconds, risking critical infrastructure failures.

### What will replace leap seconds?

A transition to 'leap hours' has been proposed, where atomic and astronomical time will drift until the difference reaches a full hour — predicted to happen no sooner than 3,000 years from now.

### Have leap seconds caused real outages in the past?

Yes, they previously caused disruptions on platforms like Foursquare, Reddit, LinkedIn, Yelp, and other services unprepared for changes in day length.