Time's up! Scientists vote to scrap the leap second - but will allow clocks to drift by an HOUR in huge shakeup

In the biggest shakeup for timekeeping in over 50 years, a key vote has severed the connection between the Earth's rotation and modern clocks.

Today, the International Bureau of Weights and Measures, known by its French acronym BIPM, voted by majority decision to abandon the 'leap second'.

First used in 1972, 27 of these extra seconds have been added to Coordinated Universal Time (UTC) to keep our clocks exactly aligned with Earth's spin.

Now, scientists around the world will allow UTC and astronomical time (UT1) to drift up to one hour, or 3,600 seconds, apart.

That means the clocks may not need to be adjusted for centuries, if not millennia, to come. 

Every day clocks will be unafected, since those are set according to local time zones and Earth's rotation, but scientists who measure time using the precise vibrations of atoms will find it easier to keep their clocks synchronised. 

The resolution was passed by a majority at the meeting of the General Conference on Weights and Measures (CGPM) in Versailles, France.

The change is scheduled to come into effect on May 20, 2027, which is also World Metrology Day.

Dr Setnam Shemar, principal scientist at the National Physical Laboratory, told the Daily Mail: 'It is a good decision overall. Leap seconds have given way to the leap hour to reduce the risks to systems that depend on accurate time.

'Humanity will still retain the important link between its global time system and the Earth’s rotation, although more loosely.'

Since 1884 the world's clocks have been synchronised according to Greenwich Mean Time.

When the sun hits its highest point over the meridian line, that is noon; and for well over 100 years that was more than accurate enough to keep the world ticking over.

However, with the rise of high-precision computing, it has become more important for clocks to be aligned to the tiniest fraction of a second.

Modern atomic clocks measure time by measuring the tiny natural vibrations in atoms, making them incredibly consistent.

The Earth, meanwhile, wobbles, speeds up and slows down over the years due to the gravity of the moon and the shifting mass of melting polar ice caps.

This creates tiny inconsistencies between the clocks in scientists' labs and the timing set by the passage of the sun overhead.

That might not seem important, but a second of delay is absolutely fatal to any system that requires accurate timing.

Data centres, like those that handle cloud computing, use time synchronisation to allow computing to be distributed across different servers.

Likewise, financial systems such as high-frequency trading use precision time stamps to ensure orders are carried out and to provide an audit trail for complying with regulations.

To solve this problem, the 69 member states of BIPM, an intergovernmental organisation that determines measurement standards, decided to start adding 'leap seconds'.

That ensured UTC and UT1 stayed perfectly in sync for as long as possible, but this arrangement also came with some major drawbacks.

The most serious is that adding an extra second causes chaos for computer systems that were never designed to have their timekeeping systems interfered with.

Dr Shemar says: 'They just didn’t find it easy to reliably implement leap seconds in their systems.

'Timing glitches, resulting from bugs in computer systems, were adversely impacting, for example, data centres and networks.'

When a leap second was added in 2012, it caused widespread disruption that brought some websites to a halt.

Reddit saw a major outage that lasted for 40 minutes when the change confused the servers' precision timers, LinkedIn briefly went down, and Qantas airline flights were delayed.

Likewise, in 2016, the addition of a leap second caused Cloudflare customers to experience outages or delays when the company's servers failed to handle the change.

Meta has been particularly outspoken about the need to ditch the leap second, writing in a blog that they are 'a major source of pain for people who manage hardware infrastructures'.

Scientists are also increasingly worried that they might need to add a 'negative leap second' by 2029, which could be even more disruptive.

Generally, the Earth's rotation has been slowing down due to the gravitational pull of the moon.

However, in the mid-2010s the planet's rotation started speeding up, with engineers predicting that they would soon need to take a second off UTC to balance the clocks.

This would require setting the entire digital world backwards one second in time in perfect unison, which many computer systems simply could not handle.

Engineers were so concerned about this possibility that they warned it could create a 'mini Y2K' event, in reference to the supposed 'Millennium Bug' that caused panic at the end of 1999.

Avoiding that scenario was a big motivation for allowing UTC and UT1 to diverge by a much bigger margin.

Under the new system, a much larger divergence between the two timekeeping systems would be allowed.

BIPM would only need to step in once the gap was big enough to require a leap hour, but this isn't expected to happen for at least 1,000 years.

Until then, systems that use atomic timekeeping can keep following UTC to stay perfectly in sync while the rest of the world continues to set our watches by Greenwich Mean Time.

Dr Shemar says: 'The overall benefit will be that systems and national infrastructure around the world will be spared the disruption that incorrectly applied leap seconds can cause.

'Today’s decision therefore removes uncertainty for those responsible for implementing and maintaining time-dependent infrastructure.'