Over 500 million years ago, during the Ediacaran period, Earth’s magnetic field significantly weakened for at least 26 million years. It was 10-30 times weaker than the present-day field.
This near collapse of the magnetic field may have played a role in facilitating the emergence of complex life on Earth during this period. A weak field could have led to increased oxygen in the atmosphere and oceans.
A weakened magnetic field would have provided less shielding from the solar wind, allowing more hydrogen to escape from the atmosphere into space. This may have pushed oxygen levels higher and allowed larger, more complex animals to evolve.
The timing of this magnetic field weakening corresponds to when the earliest complex creatures like Dickinsonia appeared in the fossil record. Prior to this, life was mainly single-celled.
Studying the magnetic recordings in ancient rocks helped scientists determine the timing of Earth’s inner core solidifying, which was a key event in strengthening the geomagnetic dynamo. Evidence suggests the inner core formed after 565 million years ago.
A collapse or near-collapse of the magnetic field for extended periods may have had unintended benefits by shifting the atmosphere’s composition in a way that facilitated greater biological innovation and diversity on Earth.
Source: CNN
