About 2,900 kilometers underground, the liquid metal "heart" of the Earth experienced an unexpected and dramatic change more than ten years ago. Research shows that in the churning "ocean" of liquid iron in the Earth's outer core, an area under the Pacific Ocean suddenly "turned around" around 2010, changing from an overall westward flow to a significantly eastward flow, which is opposite to the usual large-scale westward circulation in the Earth's outer core.
The anomaly was first captured through long-term satellite monitoring of the Earth's magnetic field. The geomagnetic field is primarily driven by the violent flow of conductive molten metal in the Earth's outer core. This "engine" that converts kinetic energy into magnetic energy is called a geodynamo (geomagnetic dynamo). It is this magnetic field that forms a protective "magnetic cage" surrounding the Earth, which not only helps the Earth maintain the atmosphere that sustains life, but also blocks a large number of harmful cosmic rays and high-energy particles from the sun, providing a key barrier to the habitability of the Earth.
Frederik Dahl Madsen, a geoscientist at the University of Edinburgh in the United Kingdom, pointed out that this large-scale flow reversal under the Pacific Ocean has raised new questions for our understanding of the behavior of the deep interior of the Earth. He said that the scientific research team now urgently needs to figure out whether this reversal is just a part of short-term fluctuations and periodic oscillations, or whether it indicates that the outer core circulation is moving towards some new stable state. To this end, the scientists emphasize that continued high-precision monitoring in the future will be crucial to track the evolution of this flow in the coming years.
The discovery is based on an analysis of 27 years of satellite data between 1997 and 2025. Previous research has shown that the Earth's outer core as a whole moves slowly westward in a pattern called an "eccentric planetary gyre." However, Madsen's team found that around 2010, the local area of the outer core located under the Pacific Ocean suddenly deviated from this existing pattern: before 2010, this area still showed weak westward flow, but after 2012, it changed to a clear and strong eastward flow. Data show that this shareholder flow continued to increase after 2012, reaching a peak around 2020, and then began to gradually weaken.
What is even more surprising is that this is not a small-scale vortex or local disturbance, but involves about 5% of the "surface" flow of the outer core, which is considerable. This signal is also different from the belt-like circulation structures surrounding the planets observed on fluid bodies such as Jupiter and Saturn. Researchers described it as more like a large piece of molten metal "suddenly changing its mind" in its usual flow direction, turning around and flowing in the opposite direction. This phenomenon challenges the previous conventional understanding of the relatively stable and slowly evolving large-scale flows in the Earth's outer core, suggesting that the Earth's interior may be more dynamic and changeable than previously thought.
What exactly triggered this "countercurrent" buried deep underground has not yet been determined, but multiple independent observations point to an abnormal time around 2010. The Earth's rotation period undergoes slight day length changes approximately every 5.8 years, and this phenomenon is thought to be related to the dynamic activity of the Earth's core. Data show that this cyclical change encountered significant disturbances around 2010, and it was not until 2014 that it returned to its normal rhythm. At the same time, seismological observations also show that the Earth's inner core may have shown signs of behavioral changes during the same period.
In addition, satellites recorded a series of so-called "geomagnetic jerks" events around 2017, which are sudden "twitches" and abnormal changes in the geomagnetic field. These events are thought to be related to turbulent activity deep within the Earth's core. The research team speculates that these anomalies in 2017 may be intrinsically related to a series of deep dynamic processes triggered or associated with the sudden change in outer core flow in 2010.
Although these deep changes sound quite "thrilling", scientists stress that there is currently no evidence of direct danger to humans on the surface. However, since the geomagnetic field plays a central role in resisting space weather and protecting the earth's environment, understanding how the "core engine" that drives its changes operates is critical to improving humankind's ability to predict geomagnetic changes and space weather events. Elisabetta Iorfida, project scientist for the European Space Agency's "Swarm" satellite, pointed out that this research raises an intriguing question: What are the dynamic processes through which the deepest structures of the Earth are coupled to each other?
She said that as the geomagnetic field continues to evolve, satellite missions are providing us with increasingly detailed pictures of the dynamics of the Earth's interior. These observations suggest that the behavior of Earth's core may be more complex and unpredictable than once thought. Relevant results have been published in the Journal of Studies of Earth's Deep Interior.
From the sudden U-turn of molten metal in the outer core, to the disrupted micro-cycle of day length, to the geomagnetic "convulsions" that appeared one after another a few years later, the year around 2010 is gradually revealed to be a critical time node for an abnormal jump of the earth's "heart". In the foreseeable future, whether this event means a longer-term cyclical oscillation or just a short-lived "sudden flash" will require more years of continuous and precise global satellite and geophysical observations to reveal what changes the invisible giant "dynamo" deep in the earth is experiencing.