2000 years ago, the magnetic field was 35% stronger than its modern value. Over the last 150 years a 10–15% decline was registered, and the rate keeps growing. Recently, a weakening in the South Atlantic region of the magnetic field caused worries among scientists.
They call it the South Atlantic Anomaly and it’s been growing year after year. In the last 50 years, the magnetic strength in the region dropped by 8%, according to the European Space Agency’s Swarm constellation of satellites’ data.
Scientists can’t figure out why this happens. This is why they call it an anomaly. Not only thy don’t know what caused it, but they can’t give a dependable answer about the migration of the anomaly. For the last decade, the South Atlantic Anomaly migrated west at a 12 miles per year speed.
Some say it is the shift between the two poles that causes the event. Once every few hundred thousand years, North and South poles bluntly change places. The last time it happened, it was 700.000 years ago. Also, it seems there is a debate as to how the poles switch, whether it is an abrupt process or a slow one that could take thousands of years.
“The mystery of the origin of the South Atlantic Anomaly has yet to be solved,” says the ESA. The bright side is that “Swarm are providing exciting new insights into the scarcely understood processes of Earth’s interior.” It’s nice to know that scientists are excited.
What’s the worst that can happen?
On Mars, the disbandment of its magnetic field caused the near-total loss of its atmosphere.
If the magnetic field weakens, the magnetosphere that acts as its extent in space might lose the protective power. The magnetosphere protects Earth’s atmosphere from the charged particles of the solar wind and cosmic rays. The ozone layer protecting Earth from ultraviolet radiation might suffer too.