CNN
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According to a new study, the impacts of human-caused climate change are so overwhelming that they’re actually messing with time.
The melting of polar ice caused by global warming is changing the rate of The rotation of the Earth and the increase in the length of each day, a trend that will accelerate during this century as humans continue to extract pollution from warming the planet, according to the study published Monday in the Proceedings of the National Academy of Sciences.
The changes are small—a matter of milliseconds a day—but in our high-tech, hyper-connected world they have a significant impact on the computing systems we’ve come to rely on, including GPS.
It’s another sign of the huge impact humans have on the planet. “This is a testament 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 dictated by the speed of the Earth’s rotation, which is influenced by a complex knot of factors. These include processes in the liquid core of the planet, the ongoing impact of the melting of large glaciers after the last ice age, as well as the melting of polar ice due to climate change.
However, for millennia, the influence of the moon has dominated, increasing the length of a day by a few milliseconds per century. The Moon exerts a pull on the Earth causing the oceans to swell toward it, gradually slowing the Earth’s rotation.
Scientists have previously made connections between melting polar ice and longer days, but the new study suggests global warming has a bigger impact on time than recent studies have shown.
In the past, the impact of climate change over time “has not been as dramatic,” said Benedikt Soja, a study author and assistant professor of space geodesy at Switzerland’s ETH Zurich.
But that could change. If the world continues to emit pollution from warming the planet, “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 world, glaciers and ice sheets are melting, and that meltwater is flowing from the poles to 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.
The process is often compared to a roller skater on ice. When the skater pulls their arms toward their body, they spin faster. But if they move the arms outward, away from the body, their rotation slows down.
The international team of scientists looked at a 200-year period, between 1900 and 2100, using observational data and climate models to understand how climate change has affected the length of the day in the past and to project its role in the future.
They found that the impact of climate change on the length of the day has increased significantly.
Sea level rise, driven by climate change, caused the length of a day to vary between 0.3 and 1 millisecond in the 20th century. However, over the past two decades, scientists calculated an increase in day length of 1.33 milliseconds per century, “significantly higher than at any time in the 20th century,” according to the report.
If pollution from warming the planet continues to rise, warming the oceans and accelerating the loss of ice in Greenland and Antarctica, the rate of change will increase, the report said. If the world is unable to curb emissions, climate change could increase the length of a day by 2.62 milliseconds by the end of the century – overtaking the moon’s natural effects.
“In almost 200 years, we will have changed the Earth’s climate system so much that we are witnessing its impact on the way the Earth rotates,” Adhikari told CNN.
A few milliseconds of extra time a day may be invisible to humans, but it has an impact on technology.
Accurate timing is vital for GPS, which everyone will have with a smartphone, as well as other communication and navigation systems. These use very precise atomic times, based on the frequency of certain atoms.
By the late 1960s, the world began using Coordinated Universal Time (UTC) to designate time zones. UTC relies on atomic clocks, but still keeps pace with the rotation of the planet. This means that at some point “leap seconds” must be added or subtracted to keep in line with the Earth’s rotation.
Some studies have also suggested a correlation between an increase in day length and a increase in earthquakes, said Mostafa Kiani Shahvandi, a study author and a geoscientist at ETH Zurich. But the link remains speculative and much more research needs to be done to establish any clear link, he told CNN.
Completed a paper on the same topic published in March that while climate change was increasingly slowing the Earth’s rotation, processes in the Earth’s core may be more important and are actually speeding it up, shortening the length of the day.
“What we’ve done is go a little further and reassess these trends,” Shahvandi said. They found that any impact from the melted core was outweighed by that of climate change.
Duncan Agnew, professor of geophysics at the University of California, San Diego and author of the March study, said the new The study still relates to his research, “and is valuable because it extends the result further into the future and looks at 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 inform “a decades-long debate about what role, exactly, climate change will play in of the length of the day”.
While there is now general agreement that climate change will have a “net effect of lengthening days,” she told CNN, there is still uncertainty about which weather-influencing 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, said ETH Zurich’s Soja. “We have to consider that we are now influencing the Earth’s orientation in space so much that we are dominating effects that have been in operation for billions of years.”