by Global warming has slowed the Earth’s rotation slightly – and it could affect how we measure time.
A study published on Wednesday found that the melting of polar ice – an accelerating trend driven mainly by human-caused climate change – has caused the Earth to spin faster than it would otherwise.
Study author Duncan Agnew, a geophysicist at the Scripps Institution of Oceanography at the University of California San Diego, said that as ice melts at the poles, it changes where the Earth’s mass is concentrated. The change, in turn, affects the planet’s angular velocity.
Agnew compared the dynamic to a virtual skater spinning on ice: “If you have a skater that starts spinning, if she lowers her arms or stretches her legs out, she’s going to slow down,” he said. But if a skater’s arms are pulled in, the skater will turn faster.
Less solid ice at the poles, therefore, means more mass around the equator – the Earth’s waist.
“What you’re doing with the melting ice is you’re taking water that’s frozen solid in places like Antarctica and Greenland, and the frozen water is melting, and you’re moving the fluids to places other on the planet,” said Thomas Herring, a professor of geophysics at the Massachusetts Institute of Technology who was not involved in the new study. “The water flows out towards the equator.”
The study suggests, in other words, that the monkey-man is influenced by a force that scholars, stargazers and scientists have been wondering about for thousands of years – something that was long thought to be a constant beyond the control of mankind.
“It’s kind of amazing, even to me, that we’ve done something that measurably changes how fast the Earth rotates,” Agnew said. “Unprecedented things are happening.”
Their study, published in the journal Nature, suggests that climate change is playing a significant enough role in Earth’s rotation to slow down the possibility of a “negative leap second”. If the polar ice had not melted, clocks around the world could need to subtract one second as early as 2026 to keep universal time in sync with the Earth’s rotation, which is affected by a variety of factors.
Instead, that prospect has been pushed back by three years due to the effect of climate change. If timekeeping organizations eventually decide to add a negative step to the second position, the adjustment could disrupt computer networks.
The reason second-order adjustments are needed is that the Earth’s daily rotation trend has slowed over time, even without climate change, even though it appears constant.
About 70 million years ago, days were shorter and lasted about 23.5 hours, according to a study in Paleoceanography and Paleoclimatology. That means that Cretaceous dinosaurs experienced a planet for 372 days in each year.
A number of key factors influence the spin of the planet – sometimes working in opposition.
Ocean tidal friction, due in part to the moon’s gravitational pull, slows the Earth’s rotation. Meanwhile, since the last Ice Age, the Earth’s crust has been rising in some regions as it responds to the weight of the ice sheets being removed. That effect changes where mass is distributed and speeds up the planet’s spin. Both of these processes are quite stable and have predictable rates.
Yet another factor is the movement of fluids within Earth’s liquid core—a wild card that could speed up or slow down how fast Earth rotates, Agnew said.
Now, melting polar ice has been added to the mix. As climate change intensifies, researchers expect the melting of ice to have an even more profound effect on how the planet turns.
“It will contribute more as time goes on and as melting accelerates, as we expect it likely will,” Herring said. He added that the new study was a thorough and solid analysis that brought together research from many scientific disciplines.
The need for timekeepers to adjust universal time to stay in sync with the Earth’s rotation is not a new phenomenon. But historically, that meant adding a leap second to the standard clock standard, as the slow rotation of the Earth (measured by the vibrations of the Earth) causes astronomical time to fall behind atomic time atom in atomic clocks).
In recent years, however, the Earth’s rotation has been faster than expected due to fluctuations in its core. That prompted timekeepers to consider — for the first time since Coordinated Universal Time was officially adopted in the 1960s — whether it might make sense to subtract a second leap to keep universal time in step with Earth’s rotation.
The melting of the polar ice bucked that trend and prevented any negative second decision point. According to Agnew’s estimates, that possibility has been delayed by three years — from 2026 to 2029 — if the current speed of the Earth’s rotation prevails.
Adding and subtracting leap seconds is a pain, as they have the potential to disrupt satellite transmission, financial and energy systems that rely on extremely precise timing. Because of that, world timekeepers voted in 2022 to end leap second additions and subtractions by 2035 and allow universal time to deviate from the speed of Earth’s rotation.
“There’s been a push since about 2000 to get rid of leap seconds,” Agnew said.
Regardless of whether clocks stop changing, the notion that the melting of white ice is affecting the Earth’s rotation speaks to how significant an issue it is. Research has already described the profound impact that ice loss will have on coastal communities.
Scientists expect sea levels to rise as the climate worsens, a process that will continue for centuries. Last year, top Polar researchers warned in a report that parts of important ice sheets could collapse and that coastal communities should prepare for many feet of sea level rise. If humanity allows average global temperatures to rise by 2 degrees Celsius, the planet could commit to more than 40 feet of sea level rise.
This article was originally published on NBCNews.com
