Earth’s magnetic poles could be about to flip

There is an old saying, attributed to Benjamin Franklin, that ‘in this world nothing can be said to be certain, except death and taxes.’ It has become a useful reminder of the transience of life. But practical students might dare to disagree: surely there are a few other things we can be sure of? The sun will rise tomorrow morning; time will keep marching forwards; a compass will always point north towards the Arctic Circle.

Or will it? Last week, two scientists wrote an article in The Conversation noting that the Earth’s magnetic field has been losing strength at ‘an alarming rate’ for the last 160 years. They believe it is related to an ‘anomaly’ in the area above southern Africa, where the field has become so weak that it no longer properly shields satellites from radiation.

This is not too alarming — the magnetic field is created by molten iron moving around the Earth’s liquid core, which means it is always fluctuating. But the scientists think it could be a sign that the magnetic poles could be preparing to flip. That trusty compass would go haywire; during the process of switching (which may itself take over 100 years) the Earth would have multiple north and south poles. When it is over, the compass would point firmly towards Antarctica.

Scientists think these switches have happened many times in the past. During the last 10 million years, they have done so roughly every 200,000 years. But the last time was around 780,000 years ago.

In other words, the Earth is due a switch.

There are two problems. Firstly, no one knows when it will happen; it could be between 100 to 2,000 years away. Secondly, no one knows how it will affect life on Earth. Potential scenarios include everything from global electricity blackouts and economic collapse, to confused pigeons losing their ability to fly home.

Most scientists are reassuring. It will not happen overnight; there will be time to prepare. However, even contemplating the idea that north could become south is troubling to some. If we cannot count on this small thing, is there anything we can count on?

Ups and downs

Nothing, say philosophical types. Everything is always changing; even the sun will stop rising eventually. Scientists are constantly revising our knowledge of the universe. One day north will be south. And it is exciting! That impermanence and possibility is what life is made of.

An interesting but irrelevant thought, say more practical thinkers. These changes will happen over hundreds, maybe thousands of years. Even if our compasses stop working, there will still be plenty of things that we can depend on. Most other ways of interacting with the world will not change. And that is comforting.