Earth’s magnetic field forms a shield around Earth, guarding against harmful solar radiation, strong winds, cosmic rays, and extreme temperature changes.
However, about 591 million years ago, Earth’s magnetic field nearly disappeared. A new study suggests that this event might have been important for the development of complex life forms.
John Tarduno, a geophysics professor at the University of Rochester in New York and the lead author of the study, explained, “In general, the field is protective. If we had not had a field early in Earth’s history water would have been stripped from the planet by the solar wind (a stream of energized particles flowing from the sun toward Earth).”
Earth’s magnetic field remained weak for 26 million years
A study, published in the journal Communications Earth & Environment on May 2nd, revealed that Earth’s magnetic field, created by the movement of molten iron in the outer core, was notably weaker than it is now for a span of at least 26 million years.
This finding also solved a long-standing geological puzzle regarding the timing of Earth’s solid inner core formation, as reported by CNN.
During the Ediacaran period, which corresponds with the timeframe of this weakened magnetic field, the earliest complex animals started emerging on the ocean floor. This era also witnessed a rise in the percentage of oxygen in both the atmosphere and ocean.
These peculiar creatures looked nothing like today’s animals. They had soft bodies resembling fans, tubes, doughnuts, and disks, like the Dickinsonia, which could grow up to 4.6 feet (1.4 meters) in size, and the slug-like Kimberella, according to the study.
Before this period, life mainly consisted of single-celled and microscopic organisms. Researchers suggest the weakened magnetic field might have contributed to an increase in atmospheric oxygen, creating conditions favorable for the evolution of early complex life forms.
Near collapse event of Earth’s magnetic field
Over time, the strength of Earth’s magnetic field has been known to change, and tiny magnetic particles trapped in crystals within rocks hold evidence of such fluctuations.
In 2019, researchers studying rocks in Quebec dating back 565 million years found initial proof of a significant weakening of Earth’s magnetic field. Their findings suggested that at that time, the magnetic field was ten times weaker than it is today.
The most recent study gathered additional geological evidence supporting this idea. Rocks from a site in Southern Brazil, dating back 591 million years, indicated an even more significant weakening of the magnetic field. In this case, the field was estimated to be thirty times weaker than its current strength.
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