The appearance of a mystery area in the South Atlantic where the geomagnetic field strength is quickly diminishing has sparked suspicion that Earth is on the verge of reversing its magnetic polarity. A new study, though, reveals that the current alterations aren’t exceptional, and that a reversal may not be in the cards after all. The research was published in the journal PNAS.
The magnetic field of the Earth works as an unseen screen against the life-threatening environment in space, as well as solar winds that would otherwise sweep the atmosphere away. However, the magnetic field is not stable, and polarity reversals occur at unpredictable intervals every 200,000 years on average. This means the magnetic North and South poles are switched around.
The strength of Earth’s magnetic field has declined by around 10% over the last 180 years. Simultaneously, in the South Atlantic, off the coast of South America, an area with an exceptionally weak magnetic field has grown. The South Atlantic Anomaly is a region where satellites have malfunctioned multiple times owing to exposure to highly charged particles from the sun. These events have sparked suspicion that we are on the verge of a polarity shift. However, according to a new study, this may not be the case.
“We have mapped changes in the Earth’s magnetic field over the past 9,000 years, and 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,” explains Andreas Nilsson, a geologist at Lund University.
The findings are based on analyses of burnt archaeological objects, volcanic samples, and sediment drill cores, all of which contain magnetic field information. Clay pots that have been cooked to over 580 degrees Celsius, solidified volcanic lava, and sediments deposited in lakes or the sea are examples of these. The items serve as time capsules, storing information about the past magnetic field. The researchers were able to measure these magnetizations and reconstruct the direction and strength of the magnetic field at specified locations and times using sensitive instrumentation.
Andreas Nilsson adds, “We have developed a new modeling technique that connects these indirect observations from different time periods and locations into one global reconstruction of the magnetic field over the past 9,000 years.”
By examining the evolution of the magnetic field, scientists can learn more about the mechanisms in the Earth’s core that generate the field. By comparing measured and predicted fluctuations in the magnetic field, the new model can also be used to date archaeological and geological records. And, more reassuringly, it has led them to a conclusion about polarity reversal speculations:
“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,” Andreas Nilsson concludes.
Image Credit: ESA/ATG medialab
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