Global warming is causing the Earth’s rotation to slow slightly, which could affect the way we measure time.

A study published Wednesday found that the melting of polar ice, a trend accelerated primarily by anthropogenic climate change, is causing the Earth to spin more slowly than it would otherwise.

Study author Duncan Agnew, a geophysicist at the Scripps Institution of Oceanography at the University of California, San Diego, said melting polar ice changes where the Earth’s mass is concentrated. This change affects the planet’s angular velocity.

Agnew likened the dynamic to a figure skater spinning around on ice. He said, “If a skater starts spinning and lowers his arms or extends his legs, he will slow down.” However, if the skater’s arms are pulled inward, the skater will rotate faster.

So less solid ice at the poles means more mass around the equator, at the Earth’s waist.

“What melting ice does is take water that has solidified in places like Antarctica or Greenland, and when that frozen water melts, it moves that liquid to other parts of the planet. “Thomas Herring said. He was a professor of geophysics at the Massachusetts Institute of Technology but was not involved in the new research. “Water flows toward the equator.”

In other words, this study shows how human influence can successfully manipulate forces that have puzzled scholars, stargazers, and scientists for millennia: forces long thought to be constants beyond human control. It suggests that it has happened.

“It’s kind of impressive, even to me, that we were able to accomplish something that measurably changed the rotational speed of the Earth,” Agnew said. “Something unprecedented is happening.”

His research, published in the journal Nature, suggests that climate change is playing a significant enough role in the Earth’s rotation to delay the possibility of a “negative leap second.” If the polar ice hadn’t melted, clocks around the world might have needed to subtract one second by 2026 to synchronize universal time with the Earth’s rotation, which is influenced by a variety of factors.

Rather, the impact of climate change has delayed that outlook by an estimated three years. If timekeeping organizations ultimately decide to add negative leap seconds, the adjustment could disrupt computer networks.

The leap second adjustment is necessary because even without climate change, the Earth’s daily rotation tends to slow down over time, even though it appears constant.

Studies show that about 70 million years ago, days became even shorter, lasting about 23.5 hours. Implications of paleoceanography and paleoclimatology. This means that Cretaceous dinosaurs experienced 372 planetary days a year.

Several important factors influence a planet’s rotation, but they sometimes act in opposition.

Due in part to the moon’s gravitational pull, tidal friction in the oceans slows the Earth’s rotation. Meanwhile, since the last Ice Age, the Earth’s crust has been uplifting in some areas in response to the removal of ice sheet weight. This effect changes the distribution of mass, causing the planet to spin faster. Both of these processes are approximately constant and have predictable rates.

Yet another factor is the movement of fluids within Earth’s liquid inner core, a wild card that can either speed up or slow down Earth’s rotation, Agnew said.

Here, melted polar ice was added to the mix. As climate change intensifies, researchers expect melting ice to have an even more profound effect on the Earth’s rotation.

“As we predict, as melting accelerates over time, its contribution will become even larger,” Herring said. He added that the new study is a thorough and robust analysis that combines research from multiple scientific fields.

The need for timekeepers to adjust universal time to match the Earth’s rotation is not a new phenomenon. But historically, this involved adding leap seconds to the common standard for clocks. This is because astronomical time lags behind atomic time (measured by the vibrations of atoms in atomic clocks) due to the slowing of the Earth’s rotation.

But in recent decades, changes in the Earth’s core have caused the Earth to rotate faster than expected. This has led timekeepers, for the first time since Coordinated Universal Time was officially adopted in the 1960s, to consider whether it makes sense to subtract leap seconds to synchronize universal time with the Earth’s rotation. Ta.

The melting of polar ice counteracted that trend, avoiding any decision points regarding negative leap seconds. According to Agnew’s estimates, if the current rate of Earth’s rotation is maintained, it will likely be delayed by three years from 2026 to 2029.

Adding or subtracting leap seconds is troublesome because it can disrupt satellite, financial, and energy transmission systems that rely on very precise timing. For that purpose, Timekeepers around the world have voted to abolish leap seconds in 2022. By 2035, addition and subtraction will shift universal time from the pace of the Earth’s rotation.

“Since around 2000, there has been a movement to abolish leap seconds,” Agnew said.

Regardless of whether the clocks ultimately change, the idea that melting polar ice is affecting the Earth’s rotation speaks to how important an issue it has become. Studies have already shown that ice loss has significant impacts on coastal communities.

Scientists predict that sea level rise will accelerate as the climate warms, a process that will continue for hundreds of years. Last year, leading polar researchers warned in a report that parts of the major ice sheets could collapse and coastal regions should brace for several feet of sea level rise. If humans allowed global average temperatures to rise by 2 degrees Celsius, Earth could see sea levels rise by more than 40 feet.