Is it true that the Earth‘s magnetic field is about to flip?
Like football teams at half time, geophysicists think that the Earth’s magnetic poles could soon switch ends with the magnetic north pole becoming south, and the magnetic south pole becoming north. Fortunately, when they say ‘soon’ geophysicists are thinking in geological timescales and they actually mean sometime in the next few thousand years.
It’s thought that the Earth’s magnetic field is generated by the molten iron core at the centre of the planet. The molten iron has currents of its own, just like an ocean, and these moving currents create the magnetic field. But the currents are not consistent and the Earth’s magnetic field moves around, with the magnetic north pole currently drifting by about 10 miles a year.
Poles flip completely
But this movement of the field is small compared to a complete flip so what is there to suggest that one is imminent? Geophysicists have been studying the lava that has seeped up from the core and through a ridge on the floor of the Atlantic Ocean. As lava cools and solidifies, it preserves the direction of the Earth’s magnetic field so looking at the rock that has formed over time gives us an idea of what has happened to the magnetic poles in the past. These studies show that the poles switch ends every half million years or so – and that we’re due for another switch in the next few thousand years.
There’s also evidence to suggest that before the Earth’s magnetic poles switch, the magnetic field slowly fades out before reappearing with the poles reversed. And our magnetic field has depleted by 5% over the last century.
Fading magnetic fields
So do we need to worry? Well, birds, sea turtles and bees may get confused as they seem to use the magnetic field to navigate. More drastically, since the Earth’s magnetic field protects us from potentially harmful radiation from the Sun, as it fades we could well be faced with a disaster on a global scale. Fortunately, there’s no evidence in the fossil record of a magnetic field switch causing a species to die out.
Find related websites about the Earth’s magnetic field with physics.org.