The way the world measures time could be heading for a major change. Scientists and national timekeeping authorities are considering whether to stop adding leap seconds to the clocks that govern everything from international communications to financial transactions.
The debate centres on a small adjustment that most people never notice but which can create significant problems for computer systems. Introduced in 1972, leap seconds help keep official time aligned with Earth's irregular rotation. Now, experts want to make global timekeeping more predictable for modern technology.
The proposal could take effect as early as May 20, 2027, if approved. However, the change is not simply about removing one second from the clock. It could reshape how official time relates to the natural movement of our planet over the coming centuries.
Why Does the World Add a Leap Second?
Most people understand a day as 24 hours, but Earth's rotation does not follow a perfectly consistent schedule. Its speed changes slightly because of several natural influences, including movements within the planet and gravitational effects from the Moon.
Meanwhile, the world's official time standard, Coordinated Universal Time (UTC), is maintained using highly accurate atomic clocks. These clocks measure time through predictable atomic behaviour rather than Earth's rotation.
Because the two systems do not always match precisely, timekeepers have historically added an extra second when necessary. This adjustment is known as a leap second.
The first leap second was introduced in 1972, and a total of 27 have been added. The most recent occurred on December 31, 2016.
Without these adjustments, official time would gradually drift away from time measured by Earth's rotation. Leap seconds have traditionally kept that difference within one second.
Why Scientists Want to End Leap Seconds
Although leap seconds help connect atomic time with Earth's rotation, they create complications for systems that depend on uninterrupted, precisely ordered timestamps.
Computer networks, telecommunications infrastructure, financial markets and data centres all rely on accurate timekeeping. An unexpected extra second can expose differences in how software and hardware handle time adjustments.
The problem is that not every system processes a leap second in the same way. Poorly handled adjustments can disrupt software or cause services to malfunction.
Past incidents have demonstrated the risks. In 2012, the introduction of a leap second was associated with outages affecting services including LinkedIn and Reddit. The incident highlighted how a seemingly minor change to the clock can create unexpected technical problems.
The proposed alternative is to allow UTC to remain continuous without inserting an extra second whenever Earth's rotation diverges from atomic time.
Under the proposal being considered, the permitted difference between official time and Earth's rotational time would eventually increase to as much as one hour. This would allow timekeeping systems to operate without frequent leap-second adjustments, potentially for centuries.
What the Proposed Change Means for Everyday Life
For most people, the immediate effects would be minimal. Phones, computers and ordinary clocks would continue displaying familiar hours and minutes.
The more significant changes would affect the systems responsible for maintaining accurate time behind the scenes. Financial transactions, scientific measurements, telecommunications and other technologies could benefit from a more predictable time standard.
However, removing leap seconds would gradually weaken the direct connection between official time and Earth's rotation.
Over long periods, the difference would accumulate. Eventually, the clock time associated with sunrise and sunset would shift relative to today's expectations unless another adjustment were introduced.
Scientists have discussed larger, much less frequent corrections, sometimes described as a possible “leap hour”. Such a correction would not be needed for a very long time, and its eventual form would depend on future decisions.
The change would therefore not make days physically longer or alter Earth's rotation. It would change how humanity manages the relationship between the planet's movement and the official clock.
What Happens Next?
The General Conference on Weights and Measures, the international body responsible for decisions on measurement standards, is meeting in Versailles, France, from October 13 to 15, 2026.
Delegates are considering proposals concerning the future of UTC, alongside other timekeeping questions, including a possible future redefinition of the second.
A proposal to introduce the new approach from May 20, 2027, is under consideration. Until the decision is confirmed, the proposed date should not be treated as a completed change.
Some countries have also raised concerns about the transition. Russia, for example, has sought more time because its GLONASS satellite-navigation system incorporates leap seconds, meaning adjustments may be needed to accommodate a new standard.
The outcome matters because global timekeeping depends on international coordination. A change must be implemented consistently across the systems that support navigation, communications, scientific research and commerce.
For now, the leap second remains part of the existing timekeeping framework. But the debate highlights a growing challenge: a system designed to keep clocks aligned with the natural world must also work reliably across the digital infrastructure modern society depends on.
If the proposal is approved, the world will not stop measuring time in seconds. Instead, it will begin a transition towards a system designed to keep official time continuous, even as Earth's rotation gradually moves out of step with it.
