From: Jennifer Chu, MIT News
Published November 24, 2015 12:10 PM

Something not to worry about, the Earth's magnetic field flipping


The intensity of Earth’s geomagnetic field has been dropping for the past 200 years, at a rate that some scientists suspect may cause the field to bottom out in 2,000 years, temporarily leaving the planet unprotected against damaging charged particles from the sun. This drop in intensity is associated with periodic geomagnetic field reversals, in which the Earth’s North and South magnetic poles flip polarity, and it could last for several thousand years before returning to a stable, shielding intensity.

With a weakened geomagnetic field, increased solar radiation might damage electronics — from individual pacemakers to entire power grids — and could induce genetic mutations. A reversal may also affect the navigation of animals that use Earth’s magnetic field as an internal compass.

But according to a new MIT study in the Proceedings of the National Academy of Sciences, the geomagnetic field is not in danger of flipping anytime soon: The researchers calculated Earth’s average, stable field intensity over the last 5 million years, and found that today’s intensity is about twice that of the historical average.

This indicates that the current field intensity has a long way to fall before reaching an unstable level that would lead to a reversal.

“It makes a huge difference, knowing if today’s field is a long-term average or is way above the long-term average,” says lead author Huapei Wang, a postdoc in MIT’s Department of Earth, Atmospheric and Planetary Sciences. “Now we know we are way above the unstable zone. Even if the [field intensity] is dropping, we still have a long buffer that we can comfortably rely on.”

Earth's magnetic field image via Shutterstock.

Read more at MIT News.