Climate change is actually making days last longer : NPR

Climate change is having far-reaching effects across the planet, but scientists are now discovering that it’s changing the planet itself: slowing down the planet’s rotation and lengthening its day ever so slightly.

As temperatures rise, large amounts of ice in Greenland and Antarctica are melting. That meltwater flows into the oceans, redistributing mass closer to the equator. With the Earth thicker near the center, it takes a little longer to rotate each day.

“In some ways, this is a testament to the severity of climate change,” says Surendra Adhikari of NASA’s Jet Propulsion Laboratory. Study just published In Proceedings of the National Academy of Sciences.

This change is so small, it takes just milliseconds, or a thousandth of a second, that it may be imperceptible to the human eye. Affects computer systems Things that control financial transactions, GPS navigation, and the power grid.

“Everyday life isn’t sensitive to the one-second level,” says Judah Levine, a physicist at the National Institute of Standards and Technology. “Technology may be sensitive, but people are using it and not realizing how sensitive it is.”

Why a day isn’t exactly 24 hours

Clocks measure a day precisely as 24 hours, but on a highly dynamic planet like Earth, an exact 24 hours is not entirely true.

“More precisely, the length of the day essentially changes every day,” Adhikari said. “Today it might be a little longer or shorter than yesterday.”

There are many forces constantly acting on the Earth’s rotation. The gravitational pull of the Moon steadily slows the Earth’s rotation by a few milliseconds per century. The rotation of the solid iron core at the center of the Earth also varies slightly, causing the Earth’s outer layers to speed up or slow down. The movement of the Earth’s crust, which is slowly recovering from being covered in ice during the last Ice Age, also affects its rotation.

now, The polar ice is melting rapidly The Earth’s mass is shifting, causing sea levels to rise near the equator: Global sea levels have risen an average of four inches since 1993, and could rise by more than two feet by the end of the century, depending on how well humans curb climate pollution caused by burning fossil fuels.

As a result, Earth became slightly wider at the center and rotated slower, similar to how a figure skater rotates: skaters with their arms outstretched rotate slower than those who keep their arms tucked in. Adhikari and his colleagues found that melting ice has slowed Earth’s rotation by 1.33 milliseconds per century since 2000; if emissions remain high, that will increase to 2.62 milliseconds by the end of the century.

Adding a leap second

That amount of time doesn’t mean much in everyday life, but it can be a problem for the highly connected computer networks that society depends on. GPS, space navigation, financial institutions and mobile phone networks all rely on time synchronization. Calibrating these clocks can be a major technical headache.

Since 1972, 27 leap seconds added Adjusting the world clock to account for the slowing of the Earth’s rotation. It is now controlled by an atomic clock.Not the rotation of the Earth. But to align that time with the planet’s rotation, they needed to add a second. Technology companies have since Opposed the adjustmentIt could potentially cause the network to collapse.

Experts now say that such decisions must take climate change into account, but melting ice has far more serious implications for the planet than time: As the polar ice melts and sea levels continue to rise, millions of people are at risk of losing their homes.

“If you live in a low-lying coastal area, you don’t have to worry about leap seconds,” Levine said. “That’s the least of your worries. There are much more serious issues to deal with.”