Earth’s magnetic field is generated through convection in the liquid iron-rich outer core. It acts as a protective shield against harmful particle radiation. During the past two centuries, field strength has decreased rapidly. The emergence of a mysterious area in the South Atlantic, where the geomagnetic field strength is declining rapidly, has led to speculation that Earth is heading towards a magnetic polarity reversal.
According to a new study, the current alterations aren’t unique, and a reversal may not be in the cards after all.
The findings are based on analyses of burnt archaeological objects, volcanic samples, and sediment drill cores containing 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 scientists 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, a geologist at Lund University, said, “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.”
“We have developed a new modeling technique that connects these indirect observations from different periods and locations into one global magnetic field reconstruction over the past 9,000 years.”
Scientists can learn more about the underlying mechanisms in the Earth’s core that generate the magnetic field by looking at how it has changed. 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.
Andreas Nilsson said, “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 et al. Recurrent ancient geomagnetic field anomalies shed light on future evolution of the South Atlantic Anomaly. DOI: 10.1073/pnas.2200749119