The sky is falling!

kiligirl (66)in #science • 5 years ago (edited)

No, it's not. But there are some Chicken Littles out there spreading a message of impending doom about the weakening and possible flipping of Earth's magnetic field.

gif source

Quick Chicken Little digression

I'll admit, I really wanted Chicken Little aka Henny Penny for that gif, but I couldn't get it to display onscreen. For fun, go here if you want to enjoy a childhood memory, if only briefly.

Back to the story - my first live Chicken Little

I met my first "Earth's magnetic field is flipping" Chicken Little around 2005; an otherwise rational, practical man whose entire face changed once he started to speak of the impending rapture once life as we know it changes forever thanks to the Earth's magnetic field flipping (this while we were supposed to be talking about substations).

According to him, "science" knew that the flip was imminent and somehow all sinners would be punished in the process. That "science" and "sin" were caught up in the same idea was enough for me to take the conversation with the proverbial grain of salt. I couldn't quite tie our planet's magnetic field to judgment of sin - it felt just a tad too random that a mechanism driven by molten iron in the planetary core could somehow select for evil, and besides, he had that look that people who hold extreme views get when they can't properly explain what they're predicting, so they opt for intensity instead.

What does it mean if our magnetic field flips?

Literally, South would become North and North South. By that, I mean that a compass you're holding which is pointing North would be pointing towards Antarctica. Admit it - that would be kinda cool. We've already seen Trump in office for two years...I think we can cope with anything that 5 years ago we assumed could never happen.

Head to this link to see an animation of how the magnetic north pole has been moving for the last 50 years:

head to this link for the animation

It could have a significant effect on animals like sea turtles and birds which use the Earth's magnetic field for navigation.

The weakening of the magnetic field has an impact on satellites.

The increased radiation, however, could mess with the navigation of satellites and aircraft as well as electrical power grids. "Were this to happen today, the increase in charged particles reaching the Earth would result in increased risks for satellites, aviation and ground-based electrical infrastructure," University of Leeds geophysicists Phil Livermore and Jon Mound wrote in an article for The Conversation.

Apparently a bonus of having a weaker magnetic field is that auroras could be visible from much lower latitudes. Having grown up with them in Canada, I can only wish these silent, majestic phenomena on my southern, er, new northern friends.

This could also require millions of geography textbooks to be republished with North America being renamed South America, and vice versa, which could lead to a rejuvenation of the publishing industry.

What causes our magnetic field, and what makes it flip?

The Earth's magnetic field is caused by the movement of molten iron within our planet's core. Geologic records show that the field has flipped in polarity up to 100 times in the past 20 million years, usually slowly. The phenomenon is accompanied by a weakening of the field in certain areas.

LiveScience explains it this way.

Oceans of molten iron are swirling deep inside the planet around the outer core. That sloshing sets up a giant bar magnet through Earth — though not a real concrete magnet, of course. This giant magnet sits at an angle of about 11 degrees from the axis around which Earth spins, according to Windows of the Universe. These poles are not in the same place as our geographic North and South poles.

And remember that swirling iron? It's constantly moving around. The result? Blobs of that iron get flipped in the opposite direction from iron atoms around them; scientists say they become "reverse-aligned." When there are enough reverse-aligned iron atoms, that giant bar magnet flips, and magnetic north becomes magnetic south.

But this bar magnet is no Olympic gymnast: The flipping isn't a quick turn but rather a gradual one, and can take between 1,000 and 10,000 years. "It's not a sudden flip, but a slow process, during which the field strength becomes weak, very probably the field becomes more complex and might show more than two poles for a while, and then builds up in strength and [aligns] in the opposite direction," Monika Korte, the scientific director of the Niemegk Geomagnetic Observatory at GFZ Potsdam in Germany, previously told Live Science.

Magnetic north and south poles have swapped places hundreds of times in Earth's history, about every several hundred thousand years or so, scientists have found. The last one happened about 780,000 years ago.

According to phys.org:

For a polarity reversal to occur, the magnetic field needs to weaken by about 90% to a threshold level. This process can take thousands of years, and during this time, the lack of a protective magnetic shield around our planet allows more cosmic rays – high-energy particles from elsewhere in the universe – to hit us. [see how the doomsday stuff sneaks in between the sciencey stuff?]

When this happens, these cosmic rays collide with more and more atoms in our atmosphere, such as nitrogen and oxygen. This produces variants of elements called cosmogenic isotopes, such as carbon-14 and beryllium-10, which fall to the surface. And by studying the quantities of these in cores, we can see when polarity reversals took place.

The last reversal occurred between 772,000 and 774,000 years ago. Since then, the field has almost reversed 15 times, called an excursion, dropping in strength significantly but not quite reaching the threshold needed before rising again. This is when we are most at risk—as the field decays and then recovers its strength. The last excursion occurred 40,000 years ago, and evidence suggests we are heading in that direction again.

'The geomagnetic field has been losing 30 percent of its intensity in the last 3,000 years,' said Dr. Thouveny. 'From this value, we predict it will drop to near zero in a few centuries or a millennia.' [millennium, but let's not get too picky]

In a wittily reassuring article, National Geographic explains this has happened before.

Based on the magnetic fingerprints locked into ancient rocks, we know that over the last 20 million years, magnetic north and south have flipped roughly every 200,000 to 300,000 years (this rate has not been constant over the planet’s lifetime, though). The last of these major reversals occurred about 780,000 years ago, although the Poles do wander around in between these larger flips.

What do the doomsayers say?

Here's a good example of controlled scientific hysteria, from phys.org.

As Earth's magnetic shield fails, so do its satellites. First, our communications satellites in the highest orbits go down. Next, astronauts in low-Earth orbit can no longer phone home. And finally, cosmic rays start to bombard every human on Earth.

This is a possibility that we may start to face not in the next million years, not in the next thousand, but in the next hundred. If Earth's magnetic field were to decay significantly, it could collapse altogether and flip polarity – changing magnetic north to south and vice versa. The consequences of this process could be dire for our planet.

Most worryingly, we may be headed right for this scenario.

'The geomagnetic field has been decaying for the last 3,000 years,' said Dr. Nicolas Thouveny from the European Centre for Research and Teaching of Environmental Geosciences (CEREGE) in Aix-en-Provence, France. 'If it continues to fall down at this rate, in less than one millennium we will be in a critical (period).' [Now he says millennium]

What do the calm voices say?

LiveScience is one of the coolest heads out there.

Earth's magnetic poles, whatever they're doing, are not going to spark chaos and kill us all — a scenario making the rounds online right now.
...
And those alleged links between magnetic pole reversals and lights out for Earth and all its creatures … well, those are more fantasy than in real life.

The whole thing reminds me of Y2K

Lifts were going to drop in their shafts. The world's banking system would topple overnight. Anything with a control system, from fancy BMWs to mining systems to military defense systems would crash out horribly. Computer systems the world over would cave with the weight of the date format changing from 19xx to 20xx. Most pundits and computer consultants agreed the world would come to an end without their intervention (anyone else thinking fox/henhouse...?). Oh yeah, and microwave ovens would no longer be able to tell time - like they ever could.