by The impacts of human-caused climate change are so great that they are reversing over time, according to new research.
The melting of polar ice caused by global warming is changing the speed of Earth’s rotation and increasing every day, a trend set to accelerate this century as humans continue to pump planet-warming pollution, according to the study was published on Monday in the Proceedings of the National Academy of Sciences.
The changes are small — milliseconds per day — but in our high-tech, hyper-connected world they have an important impact on computer systems we’ve come to rely on, including GPS.
It’s another sign of the enormous impact humans have on the planet. “This is a testament to the seriousness of ongoing climate change,” said Surendra Adhikari, a geophysicist at NASA’s Jet Propulsion Laboratory, and report author.
The number of hours, minutes and seconds that make up each day on Earth depends on the speed of the Earth’s rotation, which is influenced by a complex knot of factors. These include processes in the planet’s fluid core, the ongoing impact of the melting of massive glaciers after the last ice age, as well as the melting of polar ice due to climate change.
For thousands of years, however, the influence of the moon predominates, increasing the length of the day by a few milliseconds per century. The moon pulls on the Earth causing the oceans to move towards it, gradually slowing down the rotation of the Earth.
Scientists have previously made links between the melting of polar ice and longer days, but the new research suggests that global warming has a bigger impact on the weather than recent studies have shown.
In the past, the impact of climate change was not “so dramatic,” said Benedikt Soja, study author and assistant professor of space geodesy at Swiss university ETH Zurich.
But that could be changing. If the world continues to pump planet-warming pollution, “climate change could become the new major factor,” surpassing the role of the moon, he told CNN.
It works like this: As people move around the world, glaciers and ice sheets are melting, and that meltwater is flowing from the poles towards the equator. This changes the shape of the planet – flattening it at the poles and making more of a bulge in the center – slowing its rotation.
The process is often compared to a spinning ice skater. When the skater pulls their arms in towards their body, they turn faster. But if they move their arms out, away from their body, their spin slows down.
The international team of scientists looked at a period of 200 years, between 1900 and 2100, using observational data and climate models to understand the impact of climate change on the length of the day in the past and its role in the future to clarify.
They found that the impact of climate change on the length of the day has increased significantly.
Due to a rise in sea level due to climate change, the length of a day changed between 0.3 and 1 millisecond in the 20th century. Over the past two decades, however, scientists have calculated an increase in day length of 1.33 milliseconds per century, “much higher than at any time in the 20th century,” according to the report.
If planet-warming pollution continues to rise, warming the oceans and accelerating ice loss in Greenland and Antarctica, the rate of change is set to increase, according to the report. If the world is unable to curb emissions, climate change could increase the length of the day by 2.62 milliseconds by the end of the century — overtaking the natural effects of the moon.
“In barely 200 years, we will have changed the Earth’s climate system so much that we are witnessing its influence on the way the Earth turns,” Adhikari told CNN.
A few milliseconds of extra time a day may be imperceptible to humans but it affects technology.
Accurate time is critical to GPS, which everyone with a smartphone will have, as well as other communication and navigation systems. These use very precise atomic time, based on the frequency of a particular atom.
From the late 1960s, the world started using coordinated universal time (UTC) to set time zones. UTC relies on an atomic clock but keeps up with the rotation of the planet. That means at some point “leap seconds” need to be added or subtracted to maintain alignment with the Earth’s rotation.
Some studies have also suggested that there is a correlation between an increase in day length and an increase in earthquakes, said Mostafa Kiani Shahvandi, study author and 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.
A paper on the same topic published in March concluded that while climate change was slowing the Earth’s rotation, processes in the Earth’s core may be more important and could be speeding up. , which shortens the whole day.
“What we’ve done is go a little further and reassess these trends,” Shahvandi said. They found that the impact of the melted core was more important than the impact of climate change.
Duncan Agnew, professor of geophysics at the University of California San Diego and author of the study in March, said that the new study is still relevant to his research, “and it is valuable because it extends the result further into the future and that it looks at more than just climate. case.”
Jacqueline McCleary, an assistant professor of physics at Northeastern University who was not involved in the study, said the new research adds to “a decades-long debate about the role, exactly, that climate change will play in the change of the whole day. “
While there is now general agreement that “climate change will have a net effect of expanding the day,” she told CNN, there is still uncertainty about the time-related processes that will dominate this century. This study concludes that climate change is now the second leading factor, she said.
It is a sobering conclusion, said Soja ETH Zurich. “We have to consider that we have such an influence on the Earth’s orientation in space that we are ahead of effects that have been operating for billions of years.”
For more CNN news and newsletters create an account at CNN.com
