A new study suggests that the weakening of Earth’s magnetic field around 591 million years ago may have played a crucial role in the evolution of life. The research, published in the journal ‘Geology’, analyzed ancient rocks from South Africa and Brazil, revealing a significant weakening of the magnetic field during the Ediacaran Period (about 635 million to 541 million years ago). This period is associated with the ‘oxygenation event’, when the atmosphere and oceans became more oxygen-rich, leading to the evolution of larger and more mobile life-forms.
The magnetic field is generated by the movement of iron in the Earth’s core. Over time, as the core cooled and the temperature difference between the liquid and solid parts of the core decreased, the magnetic field weakened. The study found that the magnetic field was 30 times weaker 591 million years ago than it is today.
The weakening of the magnetic field may have allowed more hydrogen molecules to escape into space, reducing the amount of oxygen that could bind to other molecules. This led to an increase in free oxygen in the atmosphere and oceans, providing more oxygen for organisms to use. This additional oxygen may have allowed organisms to grow larger and become more mobile.
The study also suggests that the magnetic field may have disappeared altogether at some point during the Ediacaran Period. However, the crystallization of the core at the time may have provided a new source of heat, driving the movement of the liquid core and restoring the magnetic field.
The findings have implications for understanding how life might arise on other planets. They also highlight the interconnectedness of Earth’s deep geology, atmosphere, and surface environment.
