The solar wind flows around Earth’s magnetic field. A new NASA study suggests that the amount of oxygen in the atmosphere and strength of the magnetic field have been correlated for more than half a billion years.
Credit: NASA’s Goddard Space Flight Center/Conceptual Image Laboratory
NASA scientists uncovered a 540-million-year rhythm linking Earth’s shifting magnetic field to rises and dips in atmospheric oxygen, hinting that the planet’s molten core and moving continents may quietly choreograph the conditions that allow complex life to thrive.
Earth’s Magnetism and Oxygen Dance
For 540 million years, Earth’s magnetic field and the planet’s oxygen levels have followed remarkably similar patterns, according to a new analysis by NASA scientists. The findings suggest that powerful processes deep inside the Earth could be shaping the conditions that make life possible on the surface.
Earth’s magnetic field is generated by the movement of molten metal in its core, creating a protective shield around the planet much like a giant electromagnet. But this flow is not constant, and as it shifts, so does the strength of the magnetic field.
Many researchers believe this magnetic field plays a key role in shielding our atmosphere from being stripped away by high-energy particles from the Sun. While the exact details of how magnetism affects oxygen levels are still being explored, the NASA team wanted to take a step back and ask a simpler question: have Earth’s magnetic field and its oxygen levels changed in sync over time? The answer, it turns out, is yes—and the connection stretches back to the dawn of complex life.
Reading Rocks for Magnetic Clues
The history of the Earth’s magnetic fields is recorded in magnetized minerals. When hot minerals that rise with magma at gaps between spreading tectonic plates cool down, they can record the surrounding magnetic field. The minerals retain the field record as long as they are not reheated too severely. Scientists can deduce historic oxygen levels from ancient rocks and minerals because their chemical contents depend on the amount of oxygen available when they were formed. Data for both Earth’s magnetic field and oxygen extend over comparable ranges in databases that myriad geophysicists and geochemists have compiled. Until now, the authors of the new study say, no scientists had made a detailed comparison of the records.
“These two datasets are very similar,” said coauthor 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.”
When Kuang and colleagues analyzed the two separate datasets, they found that the planetary magnetic field has followed similar rising and falling patterns as oxygen in the atmosphere for nearly a half billion years, dating back to the Cambrian explosion, when complex life on Earth emerged.
Continents, Chemistry, and What’s Next
“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 coauthor Benjamin Mills, a biogeochemist at the University of Leeds.
The researchers hope to examine longer datasets to see if the correlation extends farther back in time. They also plan to investigate the historic abundance of other chemicals essential for life as we know it, such as nitrogen, to determine whether they also support these patterns. As for the specific causes linking the Earth’s deep interior to life on the surface, Kopparapu said: “There’s more work to be done to figure that out.”
The Life of Earth
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