Earth’s magnetic field nearly collapsed completely 591 million years ago, and this change, paradoxically, may have played a key role in the emergence of complex life, new research has found. The study, published in the journal Communications Earth & Environment on May 2, 2024, found that Earth’s magnetic field, created deep within the Earth between its liquid mantle and solid core, was significantly weaker than its current strength for at least 26 million years. The discovery of the prolonged weakening of Earth’s magnetic field also helped solve a long-standing geological mystery about when Earth’s solid inner core formed. This time span aligns with a period known as the Ediacaran, when the very first complex animals emerged on the seafloor as the oxygen content of the atmosphere and ocean increased. These strange animals barely resembled life today: soft fans, tubes, and donuts, and discs like Dickinsonia, which grew up to 1.4 meters in size, and the snail-like Kimberella. Before then, life was largely unicellular and microscopic. Researchers believe that a weak magnetic field may have led to increased oxygen in the atmosphere, allowing the evolution of early, complex life. “The magnetosphere shields Earth from the solar wind, thus maintaining Earth’s atmosphere. Therefore, a weaker magnetosphere means that lighter gases such as hydrogen would be lost from Earth’s atmosphere.” This combination raises the question of whether increased hydrogen ion loss in a reduced magnetic field contributed to oxygenation, ultimately allowing the diversification of the macroscopic and mobile animals of the Ediacaran fauna. Hydrogen, in fact, can escape into space through thermal and non-thermal mechanisms, resulting in net oxygenation of the atmosphere.
