Analysis of magnetic measurements from the ground and space shows that in 2010 a large area of liquid iron shifted from a weak westward flow to a strong eastward flow. Researchers still don't know whether this is a temporary fluctuation, a natural cycle, or a long-term change in the dynamics of the Earth's interior.
In 2010, an unusual change occurred thousands of kilometers beneath the Pacific Ocean: a vast area of liquid iron at the top of the The outer core The Earth's crust has shifted from a weak westward flow to a strong eastward flow. Researchers still don't know what caused the change, but a new analysis shows that the movement deep inside the Earth may be changing more rapidly than previously thought.
The study is based on magnetic field measurements collected between 1997 and 2025 at ground stations and via satellites. The researchers combined data from a trio of satellites Swarm and the CryoSat satellite European Space Agency, as well as from the German CHAMP and Danish Ørsted missions. Using the tiny changes in the magnetic field measured, they reconstructed the flow patterns near the core-mantle boundary. ([European Space Agency][1])
The hidden ocean of liquid iron
Earth's magnetic field It is formed primarily in the outer core – a thick layer of liquid iron and nickel surrounding the solid inner core. The movement of the conducting metal creates electric currents, which generate a magnetic field in a process known as the geodynamo.
The core cannot be directly reached or observed. Instead, scientists measure how the magnetic field changes on Earth’s surface and in space, and from that, infer how the conductive fluid moves at depth. The method is somewhat similar to inferring the direction of an underwater current based on the changes it causes at the sea surface.
For years, models have shown large, relatively stable flow patterns, especially a general westward movement. This pattern is also associated with a westward migration of parts of the magnetic field. However, the equatorial region beneath the Pacific Ocean is not a central part of this global vortex, and it is where the unusual change was discovered.
Change of direction within a few years
According to the model developed by the researchers, until 2010, the flow of material in the region beneath the Pacific Ocean moved slowly westward. After that, it switched to a strong eastward flow. The result challenges the notion that large-scale flow patterns in the outer core change only gradually, over decades.
Fredrik Dahl Madsen from the School of Earth Sciences at the University of Edinburgh, who led the study, explained that it is not yet clear whether this is a short-lived oscillation, part of a recurring cycle or a new steady state of core flow.
The model also suggests that the eastward flow began to weaken after 2020. Therefore, the event may represent a temporary fluctuation or a stage in a longer natural cycle, rather than a one-way change that will continue indefinitely. Only further measurements in the coming years will allow us to distinguish between the possibilities.
Possible connection to changes in the inner core
The strengthening of the eastward flow occurred around the same time that seismological and geodetic studies indicated a change in the behavior of the solid inner core. The researchers raise the possibility that there is a connection between the two processes, but emphasize that a causal mechanism has not yet been proven.
If there is a connection, it may indicate an interaction between the inner core, the liquid outer core, and the rocky mantle. The core-mantle boundary is a key region in the Earth's heat transfer and dynamics, but it is far beyond the ability to measure directly.
The study does not prove that the entire outer core has changed direction. It describes a regional reversal in the flow pattern just ahead of the core, below the equatorial part of Pacific Ocean.
Satellites that look into the depths of the Earth
The European Space Agency launched the three Swarm satellites in 2013. Each carries sensitive magnetometers that measure the strength and direction of the magnetic field. Their coordinated orbits allow signals originating in the core to be separated from signals coming from the crust, oceans, ionosphere, and magnetosphere.
Swarm was launched after the 2010 reversal, but its continuous measurements have documented the evolution of the flow over the following years. The data have also helped to identify wave-like accelerations and rapid changes in the flow structure that would otherwise have been lost in the measurement noise of less precise datasets. ([European Space Agency][1])
The ability to continuously monitor the magnetic field makes it possible to improve models that describe the geodynamo and secular change – the slow and continuous change in the magnetic field over years and decades.
No reversal of magnetic poles
Despite the use of the word “reversal,” this is not a reversal of the magnetic north and south poles, nor is it a sign that such a reversal is about to occur in the near future. The research deals with a change in the direction of the flow of material in a specific area of the outer core.
The process also has no direct impact on climate or immediate danger to humans. Its importance stems from its core role in creating the magnetic field, which deflects charged particles coming from the sun and affects navigation systems, satellite operations, and space weather models.
According to Elizaveta Jurpida, a Swarm mission scientist at the European Space Agency, the finding shows that regional changes can occur within just a decade. Tracking them could help us understand how the deepest layers of the Earth are connected to each other, and how the magnetic field that protects the planet is changing. ([European Space Agency][1])
Questions and Answers
What exactly changed direction under the Pacific Ocean?
A large region of liquid iron near the top of the outer core switched from a weak westward flow to a strong eastward flow. Not all of the outer core changed direction.
Does the change indicate an imminent reversal of the magnetic poles?
No. The study deals with a regional change in the flow of material in the core, not a reversal of the entire magnetic field. The researchers did not present evidence of an imminent pole reversal.
How can you measure movement thousands of kilometers deep?
The liquid, conductive iron in the core creates the magnetic field. By measuring small changes in the field from the ground and in space, it is possible to build models of the fluid movement that created them.
Is the change dangerous to humans?
There is no known direct danger from the change measured. This is a natural process deep within the Earth. Its importance is scientific and practical, because changes in the core affect the magnetic field over time.
Why is it necessary to continue monitoring the flow?
The next measurements will show whether the eastward flow continues to weaken, returns to the west, or stabilizes. This will help determine whether this is a temporary fluctuation, a cycle, or a long-term change.
The scientific article
Frederik Dahl Madsen, Isobel Howard, William J. Brown and Kathryn Whaler, "Principal component analysis of the 2010 reversal of core-surface flow beneath the Pacific Ocean", Journal of Studies of Earth's Deep Interior, 2026. https://doi.org/10.46298/jsedi.17268 ([Research Edinburgh][2])
For the original publication: [ ([European Space Agency][1])
More on the subject on the science website
- Earth's ancient shield: Scientists crack billion-year-old mystery of magnetic field
- Plasma storms have been found in space around Earth that is supposed to be empty.
- Is the Earth's core losing speed?
- Strange lumps in the depths of the Earth's mantle are remnants of the planet from the collision that also created the moon
- The Earth's magnetic history is written in ice
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