Earth's molten outer core is behaving in chaotic, unexpected ways

Earth’s molten outer core churns around the solid inner core, generating the planet’s magnetic field that shields it from harmful cosmic radiation. Measurements indicate the inner core rotates eastward while the outer core’s molten metal generally flows westward. Data from ESA Swarm and Cryosat missions, along with CHAMP and rsted observations, show that beginning in 2010 a region under the Pacific experienced an abrupt flow reversal, strongly flowing east for about a decade before weakening again in 2020. The cause remains unknown, but the findings suggest outer-core large-scale motions are less stable than previously believed and may be affected by hidden changes within the inner core.

"Earth's molten outer core is critical to life on our planet. Churning some 2,200 kilometers beneath the surface, it's a vast sea of liquid iron that swirls around the planet's solid inner core. This movement generates Earth's magnetic field, which shields our planet from harmful cosmic radiation. Measurements show that the inner core rotates in an easterly direction, just like Earth itself, but the molten metal of the outer core tends to flow westward."

"Beginning in 2010, that flow abruptly changed direction to the east in a region of the outer core under the Pacific Ocean. Why exactly this occurred remains a mystery but researchers are slowly gleaning clues. Using archival observations gathered between 1997 and 2025 by ESA's Swarm and Cryosat missions, which study the Earth's magnetic field and the polar ice caps, respectively, scientists pinpointed the anomalous flow of a glob of iron-rich liquid rock under the Pacific that changed direction."

"The anomalous flow strongly flowed to the east instead of the west for about a decade before weakening again in 2020. The study, which recently appeared in the Journal of Studies of Earth's Deep Interior, also incorporated data from Germany's CHAMP mission and Denmark's rsted mission. The findings suggest that the large-scale motions of the outer core are far less stable than previously thought."

"They also indicate that the outer core may be influenced by hidden shifts happening within the inner core. The large-scale flow reversal beneath the Pacific raises new questions about the behaviour of Earth's deep interior."

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