Earth’s core, a sphere of nearly pure iron 5,000 kilometers deeper and hotter than the Sun’s surface, will lose momentum and begin spinning in the opposite direction to our planet’s surface, according to a study published Monday. In Science Journal Natural Earth Sciences.
Chinese scientists from Peking University point out that this shutdown could have global consequences, such as shortening days by fractions of a second and affecting sea levels.
The two researchers who led the study, Yi Yang and Xiaotong Chang, tried to answer the puzzle that confirmed the existence of ‘another planet’ on Earth a few decades ago.
It will be a solid sphere 1200 kilometers in diameter, spinning freely in a sea of molten iron and other metals known as Earth’s outer core. The rotation of this core is like a dynamo, generating Earth’s magnetic field, which shields it from cosmic radiation and allows life to exist on the surface.
Earlier, the two Chinese scientists had already described in other studies that the Earth’s core rotates faster than the Earth’s crust, and that it rotates once every 900 years than the rest of the planet. This lack of synchronization is due to the tides and the progressive distance to the Moon slowing down the rotation of the crust, meaning that the days are not exactly 24 hours.
Researchers have evaluated more than 200 earthquakes south of the Sandwich Islands near the South Pole between 1960 and the present. These earthquakes occurred in pairs and produced identical seismic waves. But when these waves were captured at geostations in Alaska near the North Pole, they arrived out of sync after passing through the core, which is spinning faster than the crust.
Analysis by computer models shows that the core decelerated in 2009 and has been rotating slightly slower than the crust since then.
“From space, the core rotates at the same speed as the crust. But from the surface view of the seismic stations, the core is now rotating in the opposite direction to the west,” Xiaodong Song explains to El País.
Scientists say a similar ‘discontinuity’ was detected in the mid-1970s. “We speculate that there is an oscillation in the cycle every seven decades. This suggests that there is a vibration that connects all the layers of the Earth and that it occurs at a certain interval”, they continue.
“In recent years, the days have been getting shorter, probably because of the Earth’s core”, they explain, noting that normally the Earth’s center makes a complete turn, i.e. one day, one thousandth of a second faster than it did in 1970.
“The rotation of the outer core of the outer core also changes the internal gravity field and causes surface deformations, which can affect sea levels. These changes can also affect global temperatures,” the scientists warn.