Earth not due for a geomagnetic flip in the near future

This is a relief. The effects of global warming are bad enough.

http://www.eurekalert.org/pub_releases/2015-11/miot-end112315.php

Public Release: 23-Nov-2015
Earth not due for a geomagnetic flip in the near future
Researchers find geomagnetic field intensity is double the long-term historical average
Massachusetts Institute of Technology

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 has undergone multiple geomagnetic reversals over its lifetime, flip-flopping its polarity at random intervals.

"Sometimes you won't have a flip for about 40 million years; other times there will be 10 flips in 1 million years," Wang says. "On average, the duration between two flips is a few hundred thousand years. The last flip was around 780,000 years ago, so we are actually overdue for a flip."

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