The effects of a reversal

If the Earth's magnetic field decided to reverse, just how would life change? And what could we do about it?

Start by buying shares in companies that make GPS receivers. For a long period before it became truly reversed, the magnetic field would be reflecting a mixed convection pattern in the Earth's core and would not be much use for navigation.

More dangerously, as we saw in Chapter 2, the Earth's magnetic field reaches deep into space and wards off some of the most harmful solar radiation, including ultraviolet light and charged particles. So you would not want to go out for that country walk anyway, at least not without putting on a radiation suit. If you did, the rest of the plants and animals you met would not be flourishing.

Worst off would be the birds, fish and sea mammals that depend on the Earth's magnetic field to navigate, often for migrations over thousands of miles. It is not likely that magnetism is the only cue they use. They also use vision, as well as clues such as the position of the Sun in the sky. But their bodies contain magnetic materials used to help point the way, and they would suffer severe evolutionary stress if it stopped working.