Why is the geomagnetic dynamo the leading explanation for Earth’s main magnetic field?

The geomagnetic dynamo is the leading explanation for Earth’s main magnetic field because alternative theories, such as the existence of a permanent magnet within the planet, are physically untenable. Scientific measurements show that temperatures deep within the Earth exceed the Curie point—the temperature at which magnetic materials lose their magnetism—rendering the idea of a solid internal magnet impossible.1

In contrast, the dynamo mechanism provides a self-sustaining process that aligns with geophysical observations. This theory posits that fluid motion within Earth’s liquid outer core moves electrically conducting material across an existing magnetic field, generating electric currents that amplify and maintain the field. This process is driven by thermal convection and influenced by the Coriolis force, which twists the fluid motion to sustain the magnetic field's structure. Furthermore, the dynamo model successfully accounts for complex phenomena such as magnetic field reversals, which occur too rapidly to be explained by other geologic processes.23