Hidden roughly 1,400 miles beneath our feet is a churning engine of molten iron that makes all life on Earth possible. This electrically conducting molten iron core surrounds our planet’s more solid inner core, and forms what scientists call a “geodynamo.” It produces a magnetic field strong enough to protect Earth from a majority of the Sun’s harmful radiation. Just take a look at Earth’s planetary neighbor Mars, which possesses no magnetic field, and you’ll get an idea why this churning engine is so vital.
Because of the magnetic field’s immense role in our continued survival, scientists have spent centuries trying to understand the dynamics and behaviors of our life-sustaining geodynamo—and it turns out we have a lot more to learn. In a new study published in the Journal of Studies of Earth’s Deep Interior, scientists from the University of Edinburgh discovered that the molten flow of the Earth’s outer liquid core dramatically switched directions in roughly 2010 around the equatorial Pacific. This goes against the assumption that the flow of the outer core mostly travels in a westward direction (though it does tend to be weak in the middle of the Pacific).
“The large-scale flow reversal beneath the Pacific raises new questions about the behaviour of Earth’s deep interior,” University of Edinburgh’s Frederik Dahl Madsen, lead author of the study, said in a press statement. “Scientists now want to understand whether the reversal represents a short-lived fluctuation, part of a repeating oscillation, or a new stable equilibrium for core circulation.”
Madsen and his team stitched together nearly 30 years of data from ground observations and satellites, including ESA’s CryoSat and Swarm missions, as well as the German-launched CHAMP and Ørsted satellites. When all the information was assembled, the team noticed an unmistakable flow reversal in the Pacific Ocean, which moved weakly westward from 1997 until roughly 2010 before strongly reversing course eastward. The authors note that this eastward flow has ebbed since 2020 and could be tied to behavior in the inner core.
Although the outer liquid core flows in a relatively predictable westward direction, the planet is prone to what scientists call “geomagnetic jerks.” The ESA’s Swarm mission, which consists of three satellites equipped with extremely sensitive magnetometers, can distinguish magnetic signals that come from the core versus other possible sources, including the crust, ionosphere, or even the ocean. In 2017, this trio of satellites discerned that these “jerks” occur due to rising blobs of metal that formed in the planet’s core around 25 years earlier.
“Long-duration satellite magnetic measurements allow researchers to follow changes in the geodynamo in near-realtime and improve models of Earth’s magnetic field evolution,” ESA’s Swarm Mission Manager Anja Stromm, who didn’t participate in the study, said in a press statement. “Future observations from missions such as Swarm will play a crucial role.”
A drastic reversal of flow beneath the Pacific won’t impact the Earth’s magnetic field—and, by extension, our species’ survival—but it does make an important connection between the flow of the liquid outer core and the dynamic processes occurring deeper in the planet.
(Popular Mechanics)
