Recent research has suggested that the rotation of the Earth's inner core may have come to a pause or even reversed. The Earth's core is composed of the crust, the mantle, and the inner and outer cores. The solid inner core is located about 3,200 miles below the Earth's crust and is separated from the semi-solid mantle by the liquid outer core. The inner core rotates at a different speed from the Earth itself, and this rotation is driven by the magnetic field generated in the outer core and balanced by the gravitational effects of the mantle.
In order to study the rotation of the inner core, scientists at Peking University studied seismic waves from earthquakes that have passed through the inner core along similar paths since the 1960s. They found that since 2009, seismic records showed little difference, suggesting that the inner core rotation had paused. The scientists suggest that a small imbalance in the electromagnetic and gravitational forces could slow and even reverse the inner core's rotation. They believe this is part of a seven-decade cycle, and that the turning point prior to the one they detected in their data around 2009/2010 occurred in the early 1970s.
However, the speed of this rotation, and whether it varies, is still debated. Hrvoje Tkalcic, a geophysicist at the Australian National University, who was not involved in the study, stated that the inner core doesn’t come to a full stop. He added that the study’s finding means that the inner core is now more in sync with the rest of the planet than a decade ago when it was spinning a bit faster. Tkalcic also said that nothing cataclysmic is happening.
Understanding the rotation of the inner core could shed light on how the different layers of the Earth interact and other processes deep within the Earth. However, studying the Earth's core is a difficult task as the objects of study are buried thousands of kilometres beneath our feet. Scientists use geophysical inference methods to infer the Earth's internal properties, but caution must be exercised until multi-disciplinary findings confirm their hypotheses and conceptual frameworks. Tkalcic, who dedicates an entire chapter of his book to the inner core rotation, suggested that the inner core's cycle is every 20 to 30 years, rather than the 70 proposed in the latest study.
In conclusion, while the study's findings are intriguing, more research is needed to confirm and fully understand the processes at play in the Earth's core. The inner core rotation is a complex and dynamic process, and scientists must exercise caution when interpreting their findings and making hypotheses about the inner workings of our planet. Despite progress, our understanding of the inner Earth is still blurry, and we are still in the discovery stage.