The Earth's magnetic field is weakening and scientists don't know why - National Post

An unknown anomaly is causing the Earth’s magnetic force to weaken between South America and Africa, and scientists still aren’t sure why.

Recent data collected by the European Space Agency (ESA) noted that the area where the anomaly occurs, called the South Atlantic Anomaly by scientists, has seen the force weaken by more than eight per cent between 1970 and 2020.

Orbiting satellites and space craft, which rely on the planet’s magnetism to operate, have noted issues like technical malfunctions, the ESA warned. But more worryingly, a further drop in the force’s strength could impact its ability to protect the planet from solar winds and harmful cosmic radiation, they say.

Scientists observing the changes aren’t yet sure why they’re happening.

“The new, eastern minimum of the South Atlantic Anomaly has appeared over the last decade and in recent years is developing vigorously,” Jürgen Matzka, from the German Research Centre for Geosciences, told The Independent.

“We are very lucky to have the Swarm satellites in orbit to investigate the development of the South Atlantic Anomaly. The challenge now is to understand the processes in Earth’s core driving theses changes.”

The Earth’s magnetic field is generated by electric currents which arise from the mass of liquid iron swirling within the core of the planet. Research has proved that the field is in a constant flux and that every few 100,000 years, this flux actually flips the North and South magnetic poles — not the geographic ones — around. This is known as a geomagnetic reversal.

Scientists estimate that the field loses approximately five per cent of its strength every decade, but haven’t yet pinpointed how close it may be to a geomagnetic reversal. Some scientists say that the next reversal is long overdue; the last one took place over 780,000 years ago.

Some scientists have also suggested that the changes could be due to the dense rock underneath Africa called the African Large Low Shear Velocity Province. Large low-shear-velocity provinces, which form parts of the Earth’s mantle, account for the motion of tectonic plates at the surface level.

The ESA says it will continue to monitor the weakening magnetic field using its Swarm satellites.

“The mystery of the origin of the South Atlantic Anomaly has yet to be solved,” the space agency stated. “However, one thing is certain: magnetic field observations from Swarm are providing exciting new insights into the scarcely understood processes of Earth’s interior.”

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2020-05-26 17:00:00Z
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