NASA Study Finds Surprising Link Between Magnetic Field And Earth’s Oxygen Levels

For 540 million years, the ebb and flow in the strength of Earth’s magnetic field has correlated with fluctuations in atmospheric oxygen, according to a newly released analysis by NASA scientists. The research suggests that processes deep inside the Earth might influence habitability on the planet’s surface.

Earth’s early atmosphere was mainly a toxic mix of carbon dioxide, nitrogen and water vapor. Then, between 2.4 billion and 400 million years ago, oxygen levels began to increase exponentially, maybe triggered by an intense phase of volcanic degassing or the emergence of the first photosynthetic microorganisms, able to split water into hydrogen and oxygen.

Scientists can deduce historic oxygen levels by analyzing ancient rocks (like Banded Iron Formations) because their chemical composition depend on the amount of oxygen available when they were formed.

The oldest evidence of Earth’s magnetic field comes from 3.7-billion-year-old rocks preserved in Greenland. The history of the Earth’s magnetic field is recorded in magnetized minerals. When minerals that rise with magma at gaps between spreading tectonic plates cool down, they freeze into place, preserving the direction and strength of the surrounding magnetic field.

The origin of Earth’s magnetic field is not yet fully understood. However, it is widely believed that circulating currents within the molten iron-nickel alloy of the Earth’s outer core generate and sustain the field through a process known as geodynamo. Because the flow is not perfectly stable, the magnetic field fluctuates over time.

For the first time, comparing the two separate datasets, a research team at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and University of Leeds, U.K., found that Earth’s magnetic field has followed similar rising and falling patterns as oxygen in the atmosphere for nearly a half billion years.

“This correlation raises the possibility that both the magnetic field strength and the atmospheric oxygen level are responding to a single underlying process, ” explains study coauthor Benjamin Mills, a biogeochemist at the University of Leeds.

As for the specific causes linking Earth’s geodynamo to atmospheric oxygen levels the scientists can only speculate. For example, the growth and fragmentation of continents during a magnetic fluctuation can influence global weathering rates, a process that removes oxygen from the atmosphere.

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.

The study,”Strong link between Earth’s oxygen level and geomagnetic dipole revealed since the last 540 million years,” was published in the journal Science Advances.

Additional material and interviews provided by NASA.