During the past 20 million years, magnetic north and magnetic south have changed places roughly once every 200,000 to 300,000 years, according to evidence gathered from ancient rocks. However, the last major reversal -- when magnetic north pointed to Antarctica rather than to the Arctic -- occurred about 780,000 years ago, so the Earth may be overdue for another reversal. This geomagnetic process is linked to the movement of our planet’s spinning iron core. Despite a few doomsday predictions, most scientists don’t think that the next total reversal of the magnetic poles will spell catastrophe for the Earth. The reversal would take place over hundreds or thousands of years, and it may not happen anytime soon.
A world turned upside down (magnetically, at least):
- Magnetic fields are morphing, pushing, and pulling at one another all the time. Some scientists say that climate change may be related to this shift.
- The planet’s magnetic field helps to shield humans from solar and cosmic radiation. A protracted flip might mean that Earth would be slightly less protected from harmful space rays.
- Animals like birds, salmon, and sea turtles use the Earth’s magnetic field for navigation, and they could be confused during a reversal. But scientists see no evidence that it would lead to mass extinctions.