# Leap seconds may end with 2027 change

> Timekeepers plan to drop leap seconds by 2027 after Earth's rapid rotation.
- Title: Leap seconds may end with 2027 change · The Conversation
- Summary: Timekeepers plan to drop leap seconds by 2027 after Earth's rapid rotation. The General Conference on Weights and Measures will end leap seconds by 2027 to…
- Keywords: leap second, general conference on weights and measur, earth rotation, timekeeping, cesium, utc, ut1, leap year, atomic clock, 2027, science, ideas
- Source: The Conversation — https://theconversation.com/leap-seconds-have-helped-keep-clocks-synchronized-with-earths-rotation-but-their-time-may-be-over-heres-why-291017
- Author: Vahe Peroomian
- Read time: 1 min
- Topics: leap second, general conference on weights and measur, earth rotation, timekeeping, cesium, utc, ut1, leap year, atomic clock, 2027, science, ideas
## Timekeeping history
Humans didn’t always count time down to the second, but the Earth’s rotation defined a day for millennia.
## Leap year and leap second
Leap years add an extra day every four years to align calendars with Earth’s orbit, while leap seconds adjust clocks to Earth’s rotation.
## Earth’s rotation varies
Earth’s rotation isn’t uniform, causing time systems to drift by seconds over years.
## Leap second history
Since 1972, timekeepers added 27 positive leap seconds to keep atomic clocks within 0.9 seconds of Earth’s rotation.
## Leap second problems
Adding leap seconds disrupts computer systems, causing outages for companies like Reddit and Google.

> Reddit experienced an outage after a leap second was added on June 30, 2012.
## Earth’s rapid rotation
Earth has rotated faster since 2015, with 28 days in 2020 where it completed rotation before atomic clocks.
## 2026 decision
The General Conference on Weights and Measures will meet in October 2026 to end leap seconds by 2027.
## New time system
The resolution allows UTC and UT1 to differ by up to one hour, replacing leap seconds with leap hours.
## Why it matters
Astronomers and navigators must adjust for the growing time difference between atomic clocks and Earth’s rotation.
## Leap seconds end
By mid-October 2026, leap seconds may be a thing of the past, but leap years continue.
## Key takeaway

The General Conference on Weights and Measures will end leap seconds by 2027 to manage Earth's faster rotation.