Magnetic field anomaly said to be playing unique role in pole reversal

 

Scientist are studying an anomaly in Earth's magnetic field - the South Atlantic Anomaly - which they say plays a unique role in pole reversal of Earth's magnetic field.

Researchers at Rochester University have published a paper in Geophysical Research Letters where based on new data collected in Africa they have extended their record of Earth’s magnetic field back thousands of years to the first millennium. The latest data is said to be important missing piece required to better understand and explain the recent and ongoing changes in Earth's magnetic field, most prominently in an area in the Southern Hemisphere known as the South Atlantic Anomaly.

The researchers discovered that the magnetic field in the region fluctuated from 400-450 AD, from 700-750 AD, and again from 1225-1550 AD. This South Atlantic Anomaly, therefore, is the most recent display of a recurring phenomenon in Earth’s core beneath Africa that then affects the entire globe.

One obvious question that comes up is whether Earth's magnetic poles will reverse anytime soon. To this the research team says no! Researchers say their findings do not necessarily portend a complete pole reversal.

They acknowledge that this unusual behavior has occurred at least a couple of times before the past 160 years, and is part of a bigger long-term pattern, however, it’s simply too early to say for certain whether this behavior will lead to a full pole reversal.

The magnetic field is generated by swirling, liquid iron in Earth’s outer core. It is here, roughly 1800 miles beneath the African continent, that a special feature exists. Seismological data has revealed a denser region deep beneath southern Africa called the African Large Low Shear Velocity Province. The region is located right above the boundary between the hot liquid outer core and the stiffer, cooler mantle. Sitting on top of the liquid outer core, it may sink slightly, disturbing the flow of iron and ultimately affecting Earth’s magnetic field.

A major change in the magnetic field would have wide-reaching ramifications; the magnetic field stimulates currents in anything with long wires, including the electrical grid. Changes in the magnetic field could therefore cause electrical grid failures, navigation system malfunctions, and satellite breakdowns. A weakening of the magnetic field might also mean more harmful radiation reaches Earth—and trigger an increase in the incidence of skin cancer.

Even if a complete pole reversal is not in the near future, however, the weakening of the magnetic field strength is intriguing to scientists, says one of the researchers. The possibility of a continued decay in the strength of the magnetic field is a societal concern that merits continued study and monitoring, the researcher adds.