by One day in the next few years, everyone on earth will lose a second of their time. Exactly when that will happen is influenced by humans, according to a new study, as the melting polar ice changes the Earth’s rotation and changes time itself.
The rotation of the Earth determines the hours and minutes that determine our days. But that rotation is not constant; it can change ever so slightly, depending on what’s happening on Earth’s surface and in its molten core.
These almost imperceptible changes from time to time mean that the world’s clocks have to be adjusted by “leap seconds,” which can be tiny but can have a big impact on computer systems.
Many seconds have been added over the years. But after a long slowing trend, the Earth’s rotation is now speeding up due to changes in its core. For the first time ever, a second will need to be removed.
“The second negative jump has never been planted or tested, so the problems it could cause are unprecedented,” wrote Patrizia Tavella, a member of the Time Department at the International Bureau of Weights and Measures in France, in an article attached to the study. .
But exactly when this happens is affected by global warming, according to the study published on Wednesday in the journal Nature. Melting polar ice is delaying the second jump by three years, pushing it from 2026 to 2029, the report found.
“Part of figuring out what’s going to happen with global warming … depends on understanding what’s happening with the effect of global warming,” said Duncan Agnew, professor of geophysics at the University of California San Diego and author of the study.
Before 1955, a second was defined as a specific fraction of the time it took the Earth to rotate once in relation to the stars. Then came the era of highly precise atomic clocks, which created a much more stable way to define a physical second.
From the late 1960s, the world started using coordinated universal time (UTC) to set time zones. UTC relies on an atomic clock but keeps up with the rotation of the planet.
But because the rotation speed is not constant, both time scales change slowly. This means that a “leap second” must be added every now and then to bring them back into alignment.
The biggest change in the Earth’s rotation over the long term was the friction of the tides on the ocean floor – which slowed down its rotation. More recently, the impacts of polar ice melt, driven by humans burning planet-warming fossil fuels, have been a significant factor, Agnew said. As the ice melts into the ocean, meltwater moves from the poles towards the equator, further slowing the Earth’s rotation speed.
Ted Scambos, a glaciologist at the University of Colorado Boulder who was not involved in the study, describes the process as a real skater spinning with his hands over his head. As they bring their arms down towards their shoulders, their turning slows.
The melting of polar ice “is big enough to really affect the rotation of the entire Earth in a way that has never been seen before,” Agnew said. “To me, it’s amazing that humans have caused a change in the Earth’s rotation.”
But while melting ice may be slowing the Earth’s spin, another factor is at play when it comes to global warming, according to the report: processes in the Earth’s core.
The liquid core of the planet spins independently of its solid outer shell. If the core slows down, the solid shell speeds up to maintain momentum, Agnew said, and that’s what’s happening right now.
Little is known about what is going on about 1,800 miles below the Earth’s surface, and it is not clear why the speed of the core is changing. “It’s basically unpredictable,” Agnew said.
But what is clear, according to the study, is that the Earth’s rotation is speeding up overall, despite the slowing of the melting of polar ice. That means the world will soon have to subtract seconds for the first time.
“A second doesn’t sound like much,” Agnew said, but computer systems set up for activities such as stock exchange transactions must be accurate to the thousandth of a second.
Many computer systems have software that enables them to add seconds, but few can subtract one. People will have to reprogram computers, introducing the possibility of error.
“No one really expected the Earth to accelerate to the point where we would have to take a second jump,” Agnew said.
Scambos, a University of Colorado Boulder glaciologist, said the “bulk” of the study shows that “changes from the Earth’s core are outpacing the trends in ice loss from the poles – although ice loss has ahead. for the last ten years.”
“It’s a ‘yikes’ moment for some computer applications,” he told CNN, but for most people life will go on as usual.
For Agnew, the results could be a powerful tool to connect people to the ways in which humans are changing the planet.
“The fact that so much ice has melted that it’s changed the rotation of the Earth by a measurable amount, I think it gives you the sense that, okay, this is a big deal.”
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