New study shows that time itself is affected

(CNN) — One day in a few years, everyone in the world will waste one second of their time. According to a new study, humans influence exactly when this will happen, as melting polar ice changes Earth’s rotation and alters time.

The hours and minutes that make up our day are determined by the Earth’s rotation. But that rotation is not constant; There may be slight variations depending on what happens to the Earth’s surface and its molten core.

These almost imperceptible changes sometimes mean that the world’s clocks must be adjusted by “leap seconds”, which may seem small but can have a big impact on computing systems.

Many seconds have been added over the years. But after a long trend of slowing down, Earth’s rotation is now speeding up. For the first time it will be necessary to remove one second.

“A negative leap second has never been added or tested, so the problems it could create are unprecedented,” Patrizia Tavella, a member of the time department of the International Bureau of Weights and Measures in France, wrote in an article with Studio. Is. ,

When exactly that happens depends on global warming, according to a study published Wednesday in the journal Nature. According to the report, the impact of melting polar ice on Earth’s rotation slows down the date, pushing the date back by three years to 2026 to 2029.

“Part of figuring out what’s going to happen over global timescales … depends on understanding what happens with global warming effects,” said study author Duncan Agnew, professor of geophysics at the University of California, San Diego. Used to be.”

Before 1955, a second was defined as a specific fraction of the time it takes for the Earth to rotate once relative to the stars. Then came the era of high-precision atomic clocks, which proved to be a more stable way of defining the physical second.

Since the late 1960s, the world began using Coordinated Universal Time (UTC) to establish time zones. UTC is based on atomic clocks, but keeps pace with the planet’s rotation.

However, since the rotation speed is not constant, the two time scales gradually diverge. This means that a “leap second” must be added periodically to rearrange them.

Long-term changes in Earth’s rotation have been dominated by tidal friction on the ocean floor, which has slowed its rotation. Recently, the burning of fossil fuels has become a major factor in the melting of polar ice caps, Agnew said. As ice melts into the ocean, the melt water moves from the poles toward the equator, further slowing the Earth’s rotation.

Ted Scambos, a glaciologist at the University of Colorado Boulder who was not involved in the study, describes the process as being like a figure skater spinning with his arms above his head. As they bring their arms down toward their shoulders, their spin slows down.

“The melting of polar ice is so powerful that it has affected the entire Earth’s rotation in unprecedented ways,” Agnew said. “To me, the fact that humans have changed the Earth’s rotation is amazing.”

Water flowing from melting ice in Scoresby Fjord, Greenland on August 12, 2023. OLIVIER MORIN/AFP/Getty Images

But according to the report, while melting ice may be slowing Earth’s rotation, there is another factor at play when it comes to global timekeeping: processes occurring in the Earth’s core.

The planet’s liquid core rotates independently of its solid outer shell. If the core slows down, the solid shell speeds up to keep up, Agnew said, and that’s what’s currently happening.

Little is known about what happens about 2,800 kilometers below Earth’s surface, and it is not clear why the speed of the core is changing. “This is fundamentally unexpected,” Agnew said.

But what is clear, according to the study, is that although the melting of polar ice is slowing down, overall Earth’s rotation is speeding up. This means the world will soon need to subtract one second for the first time.

Agnew said, “One second doesn’t seem like a lot, but computer systems set up for activities like stock trading must be accurate to the thousandth of a second.”

Many computer systems have software that allows them to add a second, but few have the ability to subtract one. Humans would need to reprogram the computer, which would introduce the possibility of error.

“Nobody really anticipated that the Earth would accelerate to the point where we would have to eliminate a leap second,” Agnew said.

Scambos, a glaciologist at the University of Colorado at Boulder, says the “big problem” with the study is that it shows that “changes in the Earth’s core are happening now on a larger scale than the loss of ice from the poles, even though ice There has been a reduction in the loss of. There has been an increase in the last decade.”

“This is a troubling time for some computer applications, but for most people life will continue as normal,” he told CNN.

For Agnew, the findings could be a powerful tool to connect people about the ways humans are changing the planet.

“To be able to say that so much ice has melted that it has actually changed the Earth’s rotation by a measurable amount, I think it gives you the feeling that this is something significant.”