NASA finds Earth’s magnetic field may be the hidden reason oxygen has lasted for millions of years

Scientists have debated for decades whether Earth’s magnetic field plays a role in keeping the planet habitable. The question matters because Earth stands apart from other rocky worlds. It has a long-lived magnetic field generated deep inside the core. It also has an atmosphere rich in oxygen, supporting complex life for hundreds of millions of years. A NASA-funded study examines whether these two features have changed together over geological time. Rather than focusing on short events, the researchers look at slow trends across the past 540 million years. Their approach relies on existing geological records, not models or forecasts. By placing two independent datasets side by side, the study asks whether Earth’s magnetic field and surface habitability may be linked more than once assumed.Their approach relies on existing geological records, not models or forecasts. By placing two independent datasets side by side, the study asks whether Earth’s magnetic field and surface habitability may be linked more than once assumed, hinting that changes in the magnetic field might have subtly influenced climate patterns, radiation exposure, and even the evolution of early life over millions of years.To explore the question, researchers turned to rocks that formed millions of years ago. Many preserve faint magnetic signals locked in place as they cooled. These signals allow scientists to estimate the strength of Earth’s magnetic field at different times in the past. While the record is imperfect, it provides a broad picture of how the field has changed across the Phanerozoic era, revealing long-term trends, fluctuations, and occasional dramatic shifts that shaped Earth’s environment and habitability.Oxygen leaves no direct fossil of itself, but its presence shapes chemistry. Traces in sediments, soils, and fossil remains offer indirect estimates of how much oxygen was in the air. These proxies suggest that atmospheric oxygen has not been constant. Instead, it rose slowly overall, with periods of unusual abundance, especially during the late Palaeozoic, influencing the evolution, diversification, and eventual extinction patterns of many ancient life forms.A shared rise over hundreds of millions of yearsWhen the two timelines were compared, a pattern emerged. Both magnetic field strength and oxygen levels increased gradually across the same long stretch of time. Both also showed a pronounced rise between about 330 and 220 million years ago. This overlap stood out because it appeared in records built from entirely different sources.Statistical tests rule out simple coincidenceThe researchers tested whether the match could be accidental. They compared the real data with many simulated records designed to mimic noise and uncertainty. In most cases, chance alone failed to reproduce the strength of the observed link. The strongest match occurred when both records were aligned in time, with no clear delay between them.The link seems to exist only on very long timescalesShort-term fluctuations told a different story. The connection vanished when the analysis was limited to changes over a few million years. This means that the association is not the result of sudden events. It rather indicates that it reflects slow processes deep inside the Earth, which are unfolding over extremely long periods of time.Potentially, the magnetic field was significant for oxygenHaving a stronger magnetic field means being better protected from solar particles by the atmosphere that would otherwise strip gases into space. Over extremely long time scales, such protection may lead to less oxygen being lost to the atmosphere. Besides, the magnetic field is related to the core and mantle movements which govern volcanism, weathering, and the nutrient supply. All these processes determine the production and consumption of oxygen. Thus, the components of the continuum suggest a planet's deep interior supporting life on the surface in a discreet way, without any apparent signs or major changes.