Earth's Inner Core Slowdown: Shocking Study Reveals Potential Day Length Shift

The Earth’s inner core slowdown, as per reports. It is a solid sphere composed primarily of iron and nickel, and exists in a unique state of suspension within the liquid outer core, which consists of molten metals. This inner core is held in place by the force of gravity and, together with the outer core, constitutes one of the planet’s three primary layers—the other two being the mantle and the crust.

Recent research has provided compelling evidence that the Earth’s inner core has been experiencing a slowdown in its rotation relative to the planet’s surface since 2010. According to researchers, this deceleration could cause minute changes in the length of a day on Earth, altering it by fractions of a second.

Given the inner core’s inaccessibility, scientists rely on the analysis of seismic waves generated by earthquakes—recorded as seismograms—to study its behavior. John Vidale, a professor of Earth Sciences at the University of Southern California, recalled his initial reaction upon discovering the change in the seismograms: “When I first saw the seismograms that hinted at this change, I was stumped.” However, the discovery of two dozen more observations confirming the same pattern made the conclusion inescapable. Vidale, who is also the corresponding author of the study published in the journal Nature, emphasized that the inner core’s slowdown had not been observed for many decades.

Groundbreaking Study Reveals Potential Shift in Day Length Since 2010 due to Earth’s Inner Core Slowdown

This finding has sparked vigorous debate within the scientific community. Some studies have even suggested that the inner core rotates faster than the Earth’s surface. The rotation of the inner core is known to be influenced by the magnetic field generated in the outer core and the gravitational interactions within the Earth’s mantle. The current understanding is that the inner core is now rotating more slowly than the mantle, which could mean it is reversing and backtracking relative to the surface for the first time in approximately 40 years.

“Other scientists have recently proposed various models, but our latest study provides the most convincing evidence,” Vidale noted.

Another study published earlier this year in Nature explored the impact of climate change on global timekeeping. Duncan Agnew, a geophysicist at the University of California San Diego, found that the melting of ice in Greenland and Antarctica, driven by climate change, is affecting Earth’s rotation. Agnew’s research showed that the Earth’s liquid core is slowing down, causing the solid Earth to rotate faster to compensate. This adjustment has led to fewer ‘leap seconds’ being added to Coordinated Universal Time (UTC) in recent decades. Since 1972, leap seconds have been added occasionally to account for irregularities in Earth’s rotation, but this practice has become less frequent due to these compensatory mechanisms.

In their latest study, researchers analyzed seismic data from 121 repeating earthquakes—multiple seismic events occurring in the same location—observed in the South Sandwich Islands, an isolated archipelago in the South Atlantic Ocean well-known for its tremors between 1991 and 2023. Additionally, they included data from twin Soviet nuclear tests conducted between 1971 and 1974, as well as multiple French and American nuclear tests from other studies of the inner core.

This comprehensive dataset enabled the researchers to track the inner core’s rotational dynamics with unprecedented precision. The analysis revealed a distinct slowdown, providing robust evidence that the Earth’s inner core’s rotational behavior is more complex than previously understood.

The slowing of the inner core’s rotation is a significant discovery with wide-ranging implications. It not only challenges existing models of how the Earth’s core interacts with other layers but also has potential impacts on our understanding of timekeeping and the planet’s geophysical processes.

To summarize, the Earth’s inner core—a solid sphere of iron and nickel—has been observed to slow down its rotation since 2010. This discovery, supported by extensive seismic data analysis, suggests that the inner core is rotating more slowly than the mantle for the first time in about 40 years. Influenced by the magnetic field of the outer core and gravitational forces within the mantle, this deceleration could subtly alter the length of a day on Earth. These insights, emerging from studies involving repeated earthquakes and historical nuclear tests, shed new light on the dynamic and intricate nature of our planet’s interior.