A large region of molten iron in Earth's outer core beneath the Pacific Ocean shifted from westward to eastward flow in 2010, according to a study published Aug. 6, 2026, in the Journal of Studies of Earth's Deep Interior.
The study, led by Frederik Dahl Madsen of the University of Edinburgh's School of Geosciences, used satellite data from ESA's Swarm and CryoSat missions, Germany's CHAMP mission and the Ørsted mission, covering 1997 through 2025. Scientists said the cause of the reversal remains unknown, and the eastward flow has weakened since 2020, according to the study.
Madsen said in a statement that the large-scale flow reversal beneath the Pacific raises new questions about the behavior of Earth's deep interior. He said continued monitoring will be essential to determine how the flow evolves in the coming years.
The Reversal Beneath the Pacific
Earth's molten outer core lies about 2,200 kilometers below the surface. As this electrically conducting liquid iron moves, it helps generate the planet's geomagnetic field, according to the study and ESA. Earth science texts describe the metallic core as composed mainly of iron and nickel [1]. For many years, scientists studying small variations in the field concluded that much of the outer core was flowing mainly westward, the study reported.
That pattern changed in 2010. A broad area of iron-rich fluid below the equatorial Pacific shifted from a weak westward flow to a strong eastward flow, according to the study. Scientists generally viewed large-scale circulation in the outer core as relatively stable; the sudden change suggests the system can vary much more quickly than previously believed, the study stated.
The findings offer new clues about the turbulent motions responsible for producing Earth's magnetic field, according to ESA. They may also point to connections between activity in the outer core and changes taking place deeper inside the planet, ESA said.
Satellite Data and Methodology
The study combined ground-based observations with satellite measurements collected from 1997 through 2025, according to the report. Researchers used data from ESA's Swarm and CryoSat missions, along with observations from Germany's CHAMP mission and the Ørsted mission, the report said. ESA launched the three Swarm satellites in 2013; each carries highly sensitive magnetometers that can separate core magnetic signals from signals produced by the crust, oceans, ionosphere and magnetosphere, ESA officials said.
ESA Swarm Mission Manager Anja Stromme said the mission's long record of observations was essential to the research. "Swarm provides continuous global coverage over many years, allowing scientists to track how core dynamics evolve over time rather than relying only on ground-based magnetic observatories," Stromme said. According to Stromme, long-duration satellite magnetic measurements allow researchers to follow changes in the geodynamo in near-real-time and improve models of Earth's magnetic field evolution.
The measurements also revealed wave-like accelerations and rapidly shifting flow structures that could be difficult to detect in noisier datasets, according to the study.
Possible Links to the Inner Core
The research model indicates that the strong eastward flow beneath the Pacific has weakened since 2020, according to Madsen. He said the rise of the strong eastward flow is contemporary with a change in behavior in the inner core, as inferred from geodesy and seismology, and the researchers hypothesize that these changes in the deep interior are associated with the changes in flow beneath the Pacific.
The suggestion aligns with recent findings about Earth's inner core. Research published in Nature found that the inner core is not only slowing its rotation but also changing shape [3]. A separate study reported evidence of chemical stratification in the core, suggesting that it may have an onion-like layered structure [4].
Madsen said the reversal raises the possibility that the event is a short-lived fluctuation, part of a repeating oscillation, or a new stable equilibrium for core circulation.
Implications for the Magnetic Field
The movement of liquid iron in the outer core generates the magnetic field that protects Earth from charged particles released by the Sun. Changes in the field can influence navigation systems, spacecraft operations and models used to study near-Earth space weather, according to ESA. The position of Earth's magnetic north pole has long been an open question in geophysics [2].
ESA Swarm Mission Scientist Elisabetta Iorfida said the Pacific reversal challenges the idea that stable westward circulation dominates the outer core. "This study shows that regional changes can emerge rapidly within just a decade," Iorfida said. The findings may also help scientists investigate possible interactions between Earth's outer core, inner core and lower mantle, according to Iorfida.
ESA stated that the events do not pose a threat to people or the climate. The South Atlantic Anomaly, a weak spot in Earth's magnetic field, has expanded dramatically since 2014 and is drifting westward, posing risks to satellites, according to a separate report [5]. NASA researchers have also found a 540-million-year link between Earth's magnetic field strength and atmospheric oxygen levels, suggesting deep planetary processes shape habitability [6]. Future observations from Swarm will play a role in tracking the geodynamo's evolution, ESA said.
References
- Mark Hendrix. "Earth".
- Robert Matthews. "Q A".
- Lance D Johnson. "Earth's inner core reveals surprising secrets: slowing rotation and a shape shifting surface". NaturalNews.com. February 13, 2025.
- NaturalNews.com. "Earth's inner core may have an onion-like layered structure, new study reveals". NaturalNews.com. January 4, 2026.
- Cassie B. "A growing weak spot in Earths magnetic shield threatens satellites and global technology". NaturalNews.com. October 14, 2025.
- NaturalNews.com. "Scientists Uncover Surprising Link Between Earth's Magnetic Field and Oxygen Levels, Reshaping Understanding of Planetary Habitability". NaturalNews.com. July 1, 2025.
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