Earth’s Lifeline: Magnetic Field Collapse 590 Million Years Ago

According to recent research, Earth’s magnetic field, crucial for protecting the planet from intense cosmic radiation from the sun, had disappeared approximately 590 million years ago. Surprisingly, this period of absence coincided with significant advancements in early life forms on Earth.

Wentao Huang, an Earth scientist at the University of Rochester, and his team suggest that during the Ediacaran period, when macroscopic animals of the Ediacara fauna flourished, the Earth’s magnetic field was atypically weak. Previous studies have established that multicellular life evolved around 565 million years ago, which aligns closely with the timeline of the magnetic field’s collapse.

The research involved examining igneous rocks from South Africa and previously sampled rocks from Brazil, which are over 591 million years old. These rocks captured the intensity of the Earth’s magnetic field as they formed, revealing that the field strength had dwindled to its weakest level—30 times lower than today—about 500 million years ago.

This weakening of the magnetic field persisted for nearly 26 million years, a period marked by a dramatic increase in biodiversity on Earth. The researchers postulate that the diminished magnetic field might have allowed more hydrogen ions to escape the Earth’s atmosphere into space, potentially increasing oxygen levels in the oceans and atmosphere. This surge in oxygen could have fueled the diversification and complexity of life forms.

The study speculates that this increase in oxygen was crucial for supporting complex animal ecosystems, which require high oxygen levels. However, it raises the question of how early life forms survived the increased exposure to solar winds, which are typically repelled by Earth’s magnetic field. The researchers suggest that Earth’s atmosphere and oceans might have provided sufficient protection for marine life forms during this time.

However, larger terrestrial organisms might not have been so fortunate, potentially facing evolutionary challenges or dead ends due to the lack of a magnetic shield during this transformative period in Earth’s history.