A recent study has revealed a significant correlation between Earth's magnetic field and oxygen levels in the atmosphere, suggesting they have evolved in tandem over the past 540 million years. This groundbreaking discovery, led by Weijia Kuang, a senior scientist at NASA's Goddard Space Flight Center, indicates that the strength of the geomagnetic field has increased alongside the percentage of oxygen in Earth's atmosphere, particularly since the onset of the Cambrian period, approximately 541 million years ago.
According to the research findings, both the geomagnetic field and atmospheric oxygen levels spiked significantly between 330 million and 220 million years ago. However, the study does not clarify whether one factor influences the other, or if an undiscovered variable accounts for this relationship. Kuang emphasized the importance of this research in potentially narrowing down the requirements for life on other planets, in collaboration with co-author Ravi Kopparapu, a planetary scientist at NASA.
The scientists utilized two independent datasets that span the last 540 million years. The first dataset analyzed atmospheric oxygen levels, inferred from fossilized charcoal found in sediments, which serves as a historical indicator of available oxygen. The second dataset assessed the strength of the geomagnetic field, derived from magnetic signatures recorded in ancient rocks and sediments. When plotted together, a strong correlation between these two datasets emerged.
If the geomagnetic field indeed influences oxygen levels, it is likely due to its protective role against harmful space weather. Previous studies have demonstrated that the magnetic field acts as a shield, preventing the escape and erosion of atmospheric molecules that are essential for sustaining life. It also protects Earth’s flora, which are crucial for oxygen production, from harmful radiation such as X-rays and extreme ultraviolet rays.
Conversely, if atmospheric oxygen levels dictate the strength of Earth's magnetic field, the process of plate tectonics would be central to this relationship. Plate tectonics involves the continuous recycling of Earth's crust into the mantle, which may influence the geomagnetic field's strength through geochemical processes. Kuang noted that the recycling of crustal materials, including oxygen, could affect the lower mantle and subsequently impact the geomagnetic field.
The researchers also considered a third scenario where an unknown geophysical or geochemical process might be driving both the geomagnetic field and oxygen levels in the same direction over time. An intriguing spike in the data coincides with the existence of the ancient supercontinent Pangaea, which may provide a clue to understanding this connection. However, the researchers caution that this hypothesis is still in its infancy and requires further investigation.
The study’s authors are eager to explore other geophysical and geochemical factors that could further elucidate the relationship between the geomagnetic field and oxygen levels. They emphasize that collaboration among scientists is crucial, as understanding the complex system of Earth requires a multifaceted approach. “We're like kids playing with Legos, each of us having a separate piece, trying to fit them together to see the big picture,” said Kopparapu.
This pioneering research opens new avenues for understanding the interconnectedness of Earth's systems, specifically the relationship between Earth's magnetic field and oxygen levels. As scientists continue to investigate these links, they hope to uncover more about the fundamental processes that sustain life on our planet and beyond.
