New Study Reaffirms Fluctuation of Earth’s Magnetic Field Prior to Full Reversal

A team of researchers from Tel Aviv University, The Hebrew University and the University of California has used ancient jar handles to chart the strength of the Earth’s magnetic field over a 600-year period. In their paper published in Proceedings of the National Academy of Sciences, the team describes how they were able to accurately date the jar handles, which allowed for measuring the geomagnetic field over time.

The geomagnetic field shields life on Earth from a constant stream of cosmic radiation. In this new effort, the researchers sought to learn more about the intensity of the field over time using ancient evidence and to apply this information to understanding how it might behave in the future.

As the team explains, iron oxide particles embedded in clay used to make jars can be used as a measuring device because they become fixed in alignment while the clay is still soft due to the geomagnetic field – once the jar undergoes firing, the particles remain frozen in place. In addition, ancient jar makers stamped and inscribed the handles for tax purposes, leaving clear clues about when they were made.

Thus, to create a single measurement, the researchers would date a given jar handle using historical texts, then examine the iron oxide particles to get a reading regarding magnetic strength. By repeating this process for jar handles created between the 6th and 2nd centuries BCE, the team was able to create a magnetic field strength timeline.

The researchers report that the jar handles revealed a gradual reduction in field strength over the course of the six centuries under study, and that there were also spikes and drops in field strength during some time periods. They found, for example, that field strength spiked at the end of the 8th century BEC, and then sagged again afterwards, losing approximately 27 percent of its strength.

These fluctuations, the team suggests, indicate that we do not need to be worried about the weakening field that has been observed over the past 180 years-they believe it represents normal fluctuations. The new data may also help planet scientists better understand the nature of the geomagnetic field and to answer some questions, such as why fluctuations and changes in direction occur.