Mystery Dent in Earth's Magnetic Field Set To Vanish in 300 Years

A mystery dent in the Earth's magnetic field is set to vanish in 300 years, scientists have found.

Scientists have long believed that the Earth's magnetic field—which shields the planet's atmosphere from the dangers of space—is getting weaker. Discovered in 1958, the South Atlantic Anomaly is located in the South Atlantic off the coast of South America. This area is far weaker than at comparable latitudes. Scientists know this due to its impact on satellites—more radiation gets through at an area where the Earth's magnetic field is weaker. This in turn can cause technical issues for spacecraft. Scientists suspect the overall shield has gotten weaker by 10 percent over the last 180 years.

Scientists have speculated that this could eventually lead to a magnetic polarity reversal—this would cause the North and South poles to swap places. This in turn could cause huge earthquakes, climate change escalation and extinctions of species.

Magnetic fields
A stock picture shows the Earth's magnetic fields. Scientists believe a dent in the field could disappear in 300 years. Petrovich9/Getty

However, new research by Lund University—published in PNAS—suggests that this may not be the case.

Lund University scientists assessed evidence collected over 9,000 years, including burnt archaeological artifacts, volcanic samples and sediment drill cores—according to the study, these items can be used to map changes in the Earth's magnetic field over this period.

Andreas Nilsson, associate senior lecturer at Lund University and researcher on the study, said in a press release that they "developed a new modeling technique" that can connect "indirect observations from different time periods and locations." This can then be used to reconstruct the status of the magnetic field over the past 9,000 years.

By assessing the resulting data, scientists have concluded that the weakening magnetic field may not be anything new.

"Anomalies like the one in the South Atlantic are probably recurring phenomena linked to corresponding variations in the strength of the Earth's magnetic field," said Nilsson in a press release announcing the findings. "Based on similarities with the recreated anomalies, we predict that the South Atlantic Anomaly will probably disappear within the next 300 years, and that Earth is not heading towards a polarity reversal."

Other anomalies have been detected in the Earth's field, but this one is the largest. Studies into the dent have been conducted before.

In 2020, scientists said that the anomaly was "developing vigorously."

Understanding how the anomaly is developing is vital in because of its impact on orbiting satellites.

Nilsson told Newsweek that when satellites pass over the weak area, they are exposed to "higher doses of particle radiation," which can cause damage.

"A weaker magnetic field also make Earth less protected against geomagnetic storms such as the Carrington event in 1859, which was most likely caused by a coronal mass ejection from the Sun that hit Earth's magnetosphere. A similar storm today would cause widespread electrical disruptions and blackouts," Nilsson said.

Although the rate is not always consistent, the magnetic field reverses every 200,000 to 300,000 years. There have been some fears that the next one could be imminent, as the last one took place 780,000 years ago. The reassuring findings from Lund University suggest that these fears can be put to rest.

Update 6/9/22 10:55 a.m. ET: This article has been updated to include comments from Andreas Nilsson.