Recent research indicates that Earth’s inner core has significantly slowed and reversed its direction, raising questions about potential effects on the planet’s magnetic field. Published in the journal Nature, the findings highlight changes in the core’s rotation that scientists are still working to fully understand.
The inner core, discovered by Danish seismologist Inge Lehmann in 1936, lies about 3,220 miles beneath the surface and consists mainly of iron and nickel. This solid metal sphere, which can reach temperatures as high as 9,800 degrees Fahrenheit, rotates independently of the Earth due to the magnetic field and the forces exerted by the outer core and mantle.
By examining seismographic data, researchers found that the core’s rotation speed varies over a 70-year cycle. In the past, the core rotated faster than the Earth, but it has recently slowed down significantly, even reversing direction relative to the mantle by 2023. Scientists anticipate that the core will start speeding up again in the next five to ten years.
Dr. John Vidale, coauthor of the study and Dean’s Professor of Earth Sciences at the University of Southern California, said, “I think we’ve ended the debate on whether the inner core moves, and what’s been its pattern for the last couple of decades.” However, the specific effects of these changes on Earth remain uncertain.
One potential consequence of a slower-spinning core is a slight alteration in the length of a day. Additionally, the core’s movement influences the magnetic field, which protects Earth from solar radiation. Any significant change in the core’s rotation could impact this magnetic field.
Dr. Lauren Waszek, a senior lecturer of physical sciences at James Cook University in Australia, pointed out that differential rotation was hypothesized in the 1970s and ’80s, with supporting evidence emerging in the ’90s. She stressed the importance of gathering more data and using advanced interdisciplinary tools to further investigate the core’s behavior.
Waszek noted that the immediate effects on daily life are likely minimal, saying, “In terms of that effect in a person’s lifetime? I can’t imagine it means much.” While the long-term impacts are still being studied, the current changes in the core’s rotation do not appear to pose an immediate threat.
As scientists continue to monitor and analyze the inner core’s behavior, understanding its impact on Earth’s magnetic field and other geophysical processes remains a priority. The findings underscore the complexity of our planet’s inner workings and the need for ongoing research.
