Chinese research finds Earth’s inner core may have paused, or even reversed, as part of 70-year cycle

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Uploaded: 2023-01-26T12:00:15.000Z
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Geophysicists study earthquake data to conclude solid inner core may have paused rotation and begun spinning in reverse in past decade

Peking University professor says findings show inner core closely connected to changes on the Earth’s surface, including sea level and temperature

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The Earth’s core, mostly made up of iron alloy, is about 2,900km below the Earth’s surface. It is separated from the solid mantle by a liquid outer core and rotates inside the planet. Image: Shutterstock

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Published: 8:00pm, 26 Jan 2023Updated: 2:56pm, 24 Mar 2023

The inner core of the Earth may have paused its rotation and even have begun spinning in reverse over the past decade, according to a new study by two Peking University scientists.

The geophysicists said their findings showed that the Earth’s inner core oscillates around every seven decades – coinciding with variations in the length of day and the Earth’s magnetic field, as well as global sea levels and temperatures.

“The Earth seems to behave as a resonating system that involves all the major layers of the solid earth, from the surface to the inner core,” the researchers said. The duo published their findings in the peer-reviewed journal Nature Geoscience on Tuesday.

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Author Yang Yi, an associate research scientist at the SinoProbe Laboratory and Institute of Theoretical and Applied Geophysics, said their analysis of data from six decades showed that the inner core of the Earth was “rather stable” between 1964 and 1980.

From then on, the inner core sped up and rotated faster than the Earth, which rotates on its axis, until 2009 when the rotation paused. Since then, the inner core has been spinning more slowly than the Earth, thus reversing its rotation, Yang said.

The team said a similar reversed rotation was also observed in the early 1970s, likely implying an oscillating pattern of six to seven decades.

“We show surprising observations that indicate the inner core has nearly ceased its rotation in the recent decade and may be experiencing a turning-back in a multidecadal oscillation, with another turning point in the early 1970s,” they wrote.

The team said similar oscillations over a 60 to70-year period can be found in geomagentics, variations in the length of the day and changes to global mean sea levels and temperatures.