Over the southern Atlantic there is a large area where it has been measured that the earth's magnetic field is unusually weak, an anomaly.

Because the magnetic field protects against particle radiation from the sun and the rest of space, they have had to shut down the electronics of satellites that pass over the area.

Otherwise, they could have been knocked out by the radiation.

The deviation has also been regarded by some as the beginning of a reversal of the poles, i.e. that the north and south poles switch places.

The fact that the poles change places is not in itself something that harms us, but something that we quickly adapt to.

It has happened many times during the history of the earth.

But during the period of a reversal – which can take a thousand years or more – the magnetic field is weakened and this can have catastrophic consequences.

The change disappears

But the weakening over the South Atlantic appears to be something that will disappear without dramatic consequences, researchers say in a new study published in the Proceedings of the National Academy of Sciences. 

- We have used geological and archaeological material that saved information on the strength and direction of the magnetic field.

During our reconstruction of the last 9,000 years, we have found similar kinds of anomalies on Earth, says co-author Andreas Nilsson, geologist and university lecturer in Lund.

- There seems to be a regularity.

A deviation like this grows up over about 400 years, then the magnetic field recovers without any pole change.

To reconstruct 9,000 years of changes in the magnetic field, they assembled approximately 15,000 data points from different locations on Earth.

Among other things, they used drill cores with deposits from a New Zealand lake bed, potsherds from southern Africa and Icelandic lava.

Unclear why poles switch places

Reversals of the Earth's magnetic poles occur statistically approximately once every 200,000 years.

It is unclear why.

But the last time was a full 780,000 years ago, plus a sharp weakening about 42,000 years ago.

That time the magnetic field weakened without the poles switching places. 

Since the magnetic field was first measured in 1835, its strength has decreased by up to 15 percent.

The researchers now believe, based on their model, that in the next 300 years or so the magnetic field will recover and not become even weaker. 

So is the disaster canceled or postponed? 

- It is postponed, I would say, says Andreas Nilsson.