A magnetic reversal in progress ?
The South Atlantic Anomaly (SAA) is known to be growing in extent and spreading westwards from South Africa, as the Earth’s internal magnetic field rapidly weakens in this region. This may be early evidence of a forthcoming reversal in the direction of the Earth’s internal magnetic field. We do not know in detail precisely what occurs during such reversals, including the changes observed in the magnetic field and the time a reversal takes to complete. However these factors are important in knowing where the radiation risk may be increased and how the atmosphere might respond.
Earth’s magnetic field has had many highs, lows and reversals in its past. The last reversal was around 800,000 years ago. So the Earth is known to be able to re-generate its field and has done so during human pre-history. Understanding the development of the SAA may therefore be significant in understanding the reversal process and its impact on life and the natural environment.