Ancient rocks as an environmental archive<\/p>\n
How do we even know what the magnetic field or oxygen looked like hundreds of millions of years ago? The answer sits quietly in old rocks. When molten material cools, tiny magnetic minerals inside lock in the direction and strength of the field that surrounded them, like microscopic compass needles frozen in place.<\/p>\n
Oxygen levels, in turn, can be inferred from several independent proxies. Charcoal in sediments tells scientists when wildfires were common. Ratios of carbon and sulfur in rocks record how much organic matter was buried or oxidized. <\/p>\n
Together, these records map a long, if imperfect, history of atmospheric oxygen<\/a> through the eras, from the Cambrian explosion of diverse animals to the rise and breakup of supercontinents.<\/p>\n A shared engine inside the planet<\/p>\n At first glance, it might seem obvious to credit the magnetic field<\/a> itself. A stronger field can deflect more charged particles from the Sun, which should help shield the atmosphere from erosion. Yet the numbers do not really add up. <\/p>\n Calculations in the new paper indicate that oxygen loss to space is tiny compared with the huge oxygen exchanges driven by volcanism, weathering, and the global carbon cycle.<\/p>\n So the authors lean toward a different picture. Both oxygen and magnetic intensity may be responding to the same deep\u2011Earth processes. When tectonic plates assemble into supercontinents like Pangea and later break apart, they rearrange heat flow at the boundary between the rocky mantle and the liquid metal core. <\/p>\n That can alter convection in the core that powers the geodynamo while also changing volcanic degassing and weathering at the surface, which shape the long\u2011term oxygen budget.<\/p>\n Biogeochemist Benjamin J. W. Mills, a co-author based at University of Leeds, suggested that magnetic strength and oxygen may both be \u201cresponding to a single underlying process, such as the movement of Earth\u2019s continents.\u201d <\/p>\n In practical terms, that means plate tectonics might be tuning both the shield that protects our atmosphere and the chemistry of the air itself.<\/p>\n Clues for worlds beyond our own<\/p>\n![\"A](\"https:\/\/www.newsbeep.com\/uk\/wp-content\/uploads\/2026\/04\/nasa-earth-magnetic-shield-oxygen-levels-link-1.jpg\" "\\"NASA")
NASA researchers have found a strong statistical correlation between the intensity of Earth\u2019s magnetic field and atmospheric oxygen levels over the last 540 million years.<\/p>\n