Controversial “negative” leap seconds to be abandoned in favor of rare leap hour

Every second counts in a fast-paced, high-tech world. Except when it shouldn’t.

The 28th General Conference on Weights and Measures (CGPM) in Versailles in October is expected to resolve a debate over whether we should be so pedantic in our measurements of time by putting the future of the leap second to a vote.

If member feedback is any indication, Coordinated Universal Time (UTC) will be adjusted by adding an hour as needed, rather than adjusting the time by reducing it each year.

Fundamentally, the problem is the spin of our planet. It’s just not as consistent as we would like. With melting ice, changes in wind patterns, and changing tidal forces that redistribute Earth’s angular momentum, our planet’s rotation can change speed by more than a second each year.

This won’t affect your restful sleep, but if left unchecked, it could confuse global systems that coordinate your actions with fraction-of-a-second precision based on the rapid ticking of super-precise atomic clocks. Then, in 1972, the International Bureau of Weights and Measures introduced the leap second, an additional moment intended to keep UTC in line with Earth’s slightly longer days.

In total, 27 leap seconds have been included in the calendar to account for Earth’s longest days, the last of which was in 2016.

Then in 2020, the Earth began accelerating again. Not by much, but it was enough to raise the question of whether we should instead consider shaving a second off the year in about a decade.

It is far from a trivial suggestion. Leap seconds have cost businesses in the past, grounding flights and causing network failures. A negative leap second would be new territory and is unlikely to be risk-free, especially considering that few modern computer systems were designed with this type of time debt in mind.

Four years ago, CGPM members saw the writing on the wall and realized that frequent small timing adjustments were more of a headache than they were worth.

Instead, why not wait until the discrepancy grows enough to become a real problem?

This is not as irresponsible as it seems. Many tech companies, like Google, have their own solution to the millisecond problem, such as slightly lengthening a few seconds instead of cramming it all into a single quantum leap.

By waiting until UTC and the planet’s spin do not coincide by up to an hour, the official books can be adjusted much less frequently. It would only be necessary to add a leap hour every few centuries.

Although if this is the plan of attack, it should be decided as soon as possible.

Although we will know soon. If enough members vote in favor of the draft proposal, the leap hour count would begin on May 20 next year.

We can’t wait.

Fountain: Financial times