The Earth’s magnetic field reverses more often – now we know why

Underneath our feet, deep down in the Earth, liquid iron is producing the magnetic field that we all take for granted. But every now and then that magnetic field reverses or flips its polarity. What was once magnetic north becomes south – and vice versa. When these reversals take place – and why they do so – has been an enduring mystery.

But our new research shows that there is a relationship between the Earth’s magnetic field and the amount of ancient ocean floor that descends from the surface into the hot ductile mantle beneath, through a process known as subduction.