The phenomenon of magnetic pole reversal is when the magnetic north and south pole switch for hundreds of thousands of years before the process reverses itself.
Sometimes the phenomenon can happen for a “brief” interval of a few hundred years. But during the last full reversal, the whole process persisted roughly 22,000 years. And that’s pretty terrifying!
The last full reversal happened about 773,000 years ago. And it was much longer than previously thought!
As shown by data collected in lava flows from Chile, Tahiti, Hawaii, the Caribbean, and the Canary Islands, the whole process took about 22,000 years to complete.
These data were then combined to those from seafloors and Antarctic ice cores that hold a record of beryllium production in the atmosphere. It is indeed known that when the magnetic field is weak, more cosmic rays hit the atmosphere and more beryllium is produced.
The new study shows that the pole reversal process, which initiated 795,000 years ago, lasted 4,000 years, but was preceded by 18,000 years of dramatic magnetic field instability, including two excursions (very rapid magnetic reversal). So that makes a total of 22,000 years.
This estimation is more than twice as long as previously believed and in complete contradiction with a pole shift happening over a human lifetime.
Why it’s terrifying?
- After the polar flip your compass needle will tell you that North is in Antarctica and South is somewhere near Canada.
- A protracted flip means Earth might be slightly less protected from harmful space rays for longer than we would like.
- This means that everything on the planet will be exposed to higher levels of radiation, which over time could produce an increase in diseases like cancer, as well as harm delicate spacecraft and power grids on Earth.
- Animals that use Earth’s magnetic field for navigation – including birds, salmon, and sea turtles – could get lost during their routine journeys. Eventually they will sort this out.
That being said, one total bonus of having a weaker magnetic field is that auroras will be visible from much lower latitudes.
The planet’s magnetic field has decreased by about 5 percent per century since records began. But we don’t know if it suggests a reversal is imminent, if it’s the beginning of an excursion, or if it is something completely different. What do you think?