CNN
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The impacts of human-caused climate change are so severe they are disrupting the weather, according to a new study.
Melting polar ice caused by global warming is changing the speed of The Earth’s rotation and the increasing length of each day are a trend that is expected to accelerate this century as humans continue to release planet-warming pollution, according to the study published Monday in the Proceedings of the National Academy of Sciences.
These changes are small—a matter of milliseconds per day—but in our high-tech, hyperconnected world, they have a big impact on the computer systems we rely on, including GPS.
It’s another sign of the enormous impact humans are having on the planet. “It speaks to the severity of ongoing climate change,” said Surendra Adhikari, a geophysicist at NASA’s Jet Propulsion Laboratory and an author of the report.
The number of hours, minutes, and seconds that make up each day on Earth is determined by the speed of the Earth’s rotation, which is itself influenced by a complex set of factors, including processes occurring in the planet’s fluid core, the continuing impact of the melting of the vast glaciers following the last ice age, and the melting of polar ice due to climate change.
For millennia, however, it is the impact of the Moon that has dominated, increasing the length of the day by a few milliseconds per century. The Moon exerts an attraction on the Earth, causing the oceans to swell towards it, gradually slowing the rotation of the Earth.
Scientists have previously linked melting polar ice to longer days, but the new research suggests that global warming is having a bigger influence on the weather than recent studies have shown.
In the past, the impact of climate change on the weather “has not been this dramatic,” said Benedikt Soja, study author and assistant professor of space geodesy at Switzerland’s ETH Zurich.
But that could change. If the world continues to pump out planet-warming pollution, “climate change could become the new dominant factor,” overtaking the role of the moon. he told CNN.
It works like this: As humans warm the planet, glaciers and ice caps melt, and that meltwater flows away from the poles towards the equator. This changes the shape of the planet, flattening it at the poles and making it bulge more in the middle, slowing its rotation.
This process is often compared to that of an ice skater spinning. When the skater brings his arms in toward his body, he spins faster. But if he moves his arms outward, away from his body, his spin slows down.
Olivier Marin/AFP/Getty Images
Icebergs drifting along Scoresby Sound, East Greenland.
The team of international scientists studied a 200-year period, between 1900 and 2100, using observational data and climate models to understand how climate change affected day length in the past and to project its role in the future.
They found that the impact of climate change on day length has increased significantly.
During the 20th century, rising sea levels caused by climate change caused the length of the day to vary by between 0.3 and 1 millisecond. Over the past two decades, however, scientists have calculated that the length of the day has increased by 1.33 milliseconds per century, “a figure significantly higher than at any time in the 20th century,” the report said.
If global warming pollution continues to increase, warming the oceans and accelerating the melting of ice in Greenland and Antarctica, the pace of climate change will accelerate, the report said. If the world fails to rein in its emissions, climate change could increase the length of a day by 2.62 milliseconds by the end of the century, outpacing the natural impacts of the moon.
“In just 200 years, we will have changed the Earth’s climate system so much that we will see it impact the way the Earth rotates,” Adhikari told CNN.
A few milliseconds of extra time per day may be imperceptible to humans, but they have an impact on technology.
GPS, which is available to every smartphone owner, as well as other communication and navigation systems, must be able to measure time precisely. These systems use extremely precise atomic time, based on the frequency of certain atoms.
Beginning in the late 1960s, the world began using Coordinated Universal Time (UTC) to define time zones. UTC relies on atomic clocks but still keeps pace with the planet’s rotation. This means that at any given time, “leap seconds” must be added or subtracted to keep in line with the Earth’s rotation.
Some studies have also suggested a correlation between increased day length and The increase in earthquakes is a finding, said Mostafa Kiani Shahvandi, an author of the study and a geoscientist at ETH Zurich. But the link remains speculative and much research needs to be done to establish a clear connection, he told CNN.
An article on the same subject published in March concluded that As climate change increasingly slows the Earth’s rotation, processes within the Earth’s core could become more important and even speed it up, reducing the length of the day.
“We took it a step further and re-evaluated these trends,” Shahvandi said. They found that the influence of the molten core was more important than that of climate change.
Duncan Agnew, a professor of geophysics at the University of California, San Diego, and author of the March study, said the new This study is still an extension of his research, “and is valuable because it extends the result further into the future and examines more than one climate scenario.”
Jacqueline McCleary, an assistant professor of physics at Northeastern University who was not involved in the study, said the new research helps illuminate “a decades-long debate about exactly what role climate change will play in changing day length.”
While it is now accepted that climate change will have a “net effect of lengthening daylight hours,” she told CNN, there is still uncertainty about which weather-affecting processes will dominate this century. This study concludes that climate change is now the second most dominant factor, she said.
It’s a sobering conclusion, says Soja of ETH Zurich. “We have to take into account that we now influence the Earth’s orientation in space so much that we dominate effects that have been at work for billions of years.”