New NASA research demonstrates that 540 million years of Earth’s magnetic field changes have corresponded to atmospheric oxygen levels, providing new evidence that hidden processes deep within the Earth may influence surface habitability.
Throughout Earth’s long history, instability in the flow of its molten interior has caused shifts in the planet’s magnetic field. Earlier work has linked this field to the atmosphere by suggesting that it protects against energetic solar particles that might otherwise strip away atmospheric gases.
A Historical Connection
The connection between life and oxygen is well known, as most lifeforms directly depend on the gas to survive. But Earth possesses another trait unique among known rocky planets—its long-standing intrinsic magnetic field. This correlation has intrigued scientists seeking to understand what made Earth a uniquely life-supporting world. Could the magnetic field be a key ingredient in the formation and persistence of life?
In the new study, researchers took a broader approach. Rather than trying to isolate specific interactions between magnetic fields and oxygen levels, they looked back across hundreds of millions of years to see whether the two variables have fluctuated in tandem—potentially revealing a deeper connection.
Much like tree rings provide climate data, magnetized minerals serve as a natural archive of Earth’s magnetic field over long timescales. As tectonic plates spread, magma containing hot minerals rises to fill the resulting gaps. As it cools and hardens near the surface, the rock locks in a record of the planet’s magnetic orientation. Unless later reheated to extreme temperatures, these magnetic imprints remain intact for eons.
Remarkably, these same rocks and minerals also preserve chemical signatures that reflect the amount of atmospheric oxygen present at the time they formed. Scientists can analyze these chemical contents to reconstruct past oxygen levels.
Comparing Magnetic Field and Atmospheric Data
Much of the necessary groundwork—gathering rock samples and analyzing their properties—had already been completed prior to this study. Vast databases hold information on Earth’s magnetic and atmospheric history spanning the past 540 million years. However, no one had yet performed a detailed comparison of the two datasets.
“These two datasets are very similar,” said co-author Weijia Kuang, a geophysicist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “Earth is the only known planet that supports complex life. The correlations we’ve found could help us to understand how life evolves and how it’s connected to the interior processes of the planet.”
During the Cambrian Explosion—about 540 million years ago—when complex life emerged, the two datasets show a clear alignment between Earth’s magnetic field strength and atmospheric oxygen levels. According to the team’s analysis, the correlation persists throughout the past half-billion years. Particularly notable are peaks in both oxygen and magnetic field strength around 330 million and 220 million years ago.
“This correlation raises the possibility that both the magnetic field strength and the atmospheric oxygen level are responding to a single underlying process, such as the movement of Earth’s continents,” said study co-author Benjamin Mills, a biogeochemist at the University of Leeds.
Looking in New Directions
While the correlation is now well documented, its underlying cause remains uncertain. One possibility is that the magnetic field’s shielding effect plays a key role in preserving Earth’s habitability against damaging space weather.
To explore this further, the research team has proposed two main avenues for future study. One is to extend the dataset further into the past, to determine if the magnetic field–oxygen relationship existed earlier in Earth’s history. The second is to add new dimensions to their analysis by examining other life-associated chemicals across the same time periods, seeking similar links between inner Earth processes and surface habitability.
“There’s more work to be done to figure that out,” co-author Ravi Kopparapu of the NASA Goddard Space Flight Center said.
The paper “Strong Link Between Earth’s Oxygen Level and Geomagnetic Dipole Revealed over the Last 540 Million Years” appeared on June 13, 2025, in Science Advances.
Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org, and follow him on Twitter @mdntwvlf.