Climate change has been blamed for many dramatic effects on our planet and our lives. Now it may even affect the measurement of time.
You’ve probably heard of “leap seconds” — the sliver of time scientists occasionally add to the world’s official time standard to resolve a divergence between old-fashioned time-telling and modern atomic clocks.
But we’re nearing a year when a negative leap second could be needed to shave time — an unprecedented step that will depend in part on how climate change affects the Earth’s rotation, according to a new study.
Why is one second such a big deal?
In our technologically interconnected era, many devices and systems rely on sharing a certain awareness of precisely what time it is. While leap seconds have largely been absorbed into current mechanisms, experts say, a negative leap second — or, a minute with only 59 seconds — could pose an entirely new challenge.
“Even a few years ago, the expectation was that leap seconds would always be positive, and happen more and more often,” Agnew said on the website of the Scripps Institution of oceanography at the University of California San Diego.
But because of new dynamics affecting how fast the Earth rotates, he added, a negative leap second now seems just years away.
“One second doesn’t sound like much, but in today’s interconnected world, getting the time wrong could lead to huge problems,” he said.
Leap seconds have had critics for a long minute, in part because of the havoc they can wreak on things like online reservation and retail systems. A couple years ago, engineers at Meta railed against it, stating, “Introducing new leap seconds is a risky practice that does more harm than good” and should be replaced.
Worth noting: “In 2012, a leap second caused a major Facebook outage, as Facebook’s Linux servers became overloaded trying to work out why they had been transported one second into the past,” the Data Center Dynamics website noted.
Why do we have leap seconds?
They were created as a way to reconcile deviations between traditional astronomical time and the newer international reference based on atomic clocks, known as Coordinated Universal Time or UTC. It’s a process that for years has been complicated by variations in the Earth’s rotation.
“By the 1960s, Earth was and had been decelerating, and so rotating more slowly than in the nineteenth century, which defined the atomic second,” Agnew writes.
How is climate change involved?
First things first: Earth’s rotation isn’t neat like a well-spun top. There’s a distinct wobble — and it can be affected by a number of factors, from powerful earthquakes to what’s going on in the planet’s core to how water is distributed.
The dynamics are complex; there’s even a gravitational field produced by huge ice sheets and glaciers to take into account.
Decades ago, scientists noticed the Earth was slowing down. But more recently, they’ve seen the planet’s rotation speeding up. In the summer of 2022, NPR even noted one of the shortest days ever recorded.
Changes in polar ice mass have delayed this eventuality by another three years, to 2029,” writes Harvard University geophysicist Jerry Mitrovica in Nature’s discussion of the new study.