In the early 1900s, scientists discovered that rocks of volcanic origin had variable magnetisation direction. Some measurements indicated a magnetisation in the same direction as the current magnetic field, others indicated a completely opposite magnetisation, creating “magnetic anomalies”.From these observations, the idea was born that the Earth’s magnetic field could reverse episodically. This assumption has been substantiated over time and there are now magnetic polarity scales that record and date the various inversions that have occurred during the Earth’s history.
The magnetic field has reversed about 300 times over the last 200 million years. The last reversal occurred 773,000 years ago.
When is the next pole reversal ?
Is the current acceleration of the North magnetic pole shift a sign of a short term reversal ? Nothing is less certain, with the South pole remaining relatively stable. An inversion would take place over a relatively short period of time… from 1,000 to 20,000 years at the most. The current state of our knowledge does not allow us to predict when the next inversion will occur.. You can keep on trusting your compass for now !
