Another issue is that the 20,000-year average is pretty uncertain, and this hasn’t held throughout Earth’s history. “In terms of whether we are due for a reversal, it is not possible to say,” Livermore added.
“Although the strength of the dipole is currently decreasing, this behavior is not anomalous,” based on the geological record. “Previous episodes of decay have not resulted in a reversal, merely a ‘blip’ in the field strength over time.”
A reversal, or a general weakening of the planet’s magnetic field, does present some potential threats, especially if it gets as low as 10 percent of its total strength before regenerating again.
Still, the risks are likely not to be severe. During the Brunhes-Matuyama reversal, we know from the fossil record that plant and animal life was just fine. Per NASA, there was no noticeable change in geological activity either, be that seismic, volcanic, or glacial. Earth’s rotation remained steady.
“The main issue is what might happen to our electrical infrastructure – satellites, power grids, and so on,” Livermore noted. If dangerous space weather brings highly energetic particles along with it quickly and voluminously, they will have a far easier time getting into our atmosphere without a strong magnetic field.
Satellites within the South Atlantic Anomaly – a notable magnetic field weak spot – are already at a high risk of damage.
The damage really depends on the severity of the space weather; if it’s severe, and we’re unprepared, it could result in a few major, prolonged blackouts at the surface. Biological life, however, will probably be just fine. Animals relying on magnetoreception to navigate may be a tad bemused for a while, but that’s likely to be it.
So don’t worry too much. There’s a lot of uncertainty here, but we wouldn't bet on a surprise apocalypse.