Why we do not need to panic about a sudden change

For a moment, I thought we had to face a new global threat, alongside our big favorites, like climate change, nuclear war and pandemics.

This would have been welcome from a journalistic point of view, as there is a constant need for new scary topics to write on. Otherwise, we would miss our first task, which is to provide elements to separate ads.

I also felt a certain personal indignation because the new potential threat – the imminent reversal of the Earth's magnetic field – was undermining one of the few practical skills I had kept at the beginning of my career in various navies: the ability to navigate with a magnetic compass.

My naval career did not go back to the age of sailing: we had gyro compasses and long-range radio positioning systems (although it was not the full-featured satellite GPS of today). ; hui).

However, the navy, in its wisdom, foresaw that in a major war, all outside aids to navigation would be quickly closed or carried away.

We would always have our gyroscopic compass, which would tell us where the real North is – but only one internal power outage and we would lose it too. If that happens, we should go back to the main navigation tool before the twentieth century, the magnetic compass, which does not depend on an external power source.

Unfortunately, the magnetic compass points to the magnetic North Pole, which is at a different location than the true North Pole. But it was throughout my life, and even many lives before, in much the same place.

The magnetic north pole wandered a little bit in time, but it was following a fairly predictable path around a relatively small territory among the islands of the Canadian Arctic.

All the graphs thus showed the difference ("variation") between true north and magnetic north in the part of the world covered by the graph, and even how much this difference would change each year.

We were trained to add the annual shift of the magnetic pole since the map was printed on local "variation" with respect to true north. Applying this difference, we could navigate and navigate accurately with the help of the magnetic compass.

It was a skill for which demand was very limited, but potentially useful in an emergency.

Alas, the North Magnetic Pole left his home about 30 years ago and is now heading for Siberia at a speed of 60 km per year.

It moves quickly because it is the movements inside the outer core of the Earth that generate the planet's magnetic field. The currents inside this vast volume of liquid nickel-iron change from time to time and, when they do, they can also move the magnetic poles.

Browsers can cope with it, as it is now easy to update information about changes in local magnetic variation from true north.

Maps are actually computer programs nowadays and the competent authorities are updating them more frequently than before. The concern is that this type of behavior of the magnetic pole could signal an imminent rocking during which the north and south magnetic poles change places.

According to geological data, the Earth's magnetic field had already reversed its polarity at least 183 times before, without this happening.

It will now be the other end of the needle pointing to magnetic north, but the magnetic field will still perform its primary function of trapping high energy particles that would otherwise give radiation to the planet's surface.

What is scary is the transition, which can last up to 1,000 years or a lifetime, because during this transition, the strength of the magnetic field of the planet falls to about 5% of normal. If the hole in the ozone layer worries you a bit, it should scare you – and the strength of the magnetic field is already down.

That was my initial reaction to the news. Every decade seems to announce a new way for the universe to kill us. But no, it turns out that this one.

Scientists agree that the surface of the planet is not bombarded by hard radiation during the time intervals when the magnetic field generated by the Earth disappears almost completely.

Instead, the solar wind itself induces a magnetic field at the upper limit of the planet's atmosphere (the ionosphere) that prevents incoming high energy particles from reaching the surface.

We may have the opportunity to check the validity of this forecast in the near future, but for the moment there is no reason to panic. And if you are lost in the woods (or at sea), you can always trust your compass. More or less …

This article originally appeared in The New Zealand Herald and has been reproduced with permission.