Earth's magnetic poles could start to flip. What happens then?

December 7, 2018 by Jonathan O'callaghan, From Horizon Magazine, Horizon: The EU Research & Innovation Magazine
The magnetic field protecting our planet originates deep in the Earth's core but fluctuates in strength over time. Credit: ESA/ATG medialab

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 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 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).'

Dr. Thouveny is one of the principal investigators on the five-year EDIFICE project, which has been running since 2014. Together with his colleagues, he has been investigating the history of Earth's magnetic , including when it has reversed in the past, and when it might again.

Cosmic rays

Our planet's magnetic field is predominantly created by the flow of liquid iron inside the core. It has always been a feature of our planet, but it has flipped in polarity repeatedly throughout Earth's history. Each time it flips – up to 100 times in the past 20 million years, while the reversal can take about 1,000 years to complete – it leaves fossilised magnetisation in rocks on Earth.

By taking cores—or columns—of sediments from the sea floor, like a long straw that can extend down up to 300 metres with the help of a drill, we can look back in time and see when these reversals occurred. Dr. Thouveny and his team looked at two particular forms of elements that allowed them to probe the history of our planet's magnetic field in greater detail.

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.

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.'

The Earth's magnetic field has been weakening over the South Atlantic (blue region). Credit: ESA/DTU Space

Today, we can already see the effects of a weakened magnetic field on our satellites in orbit.

In the Atlantic Ocean between South America and Africa, there is a vast region of Earth's magnetic field that is about three times weaker than the field strength at the poles.

This is called the South Atlantic Anomaly (SAA), and it's the focus of the CoreSat project being led by Professor Chris Finlay from the Technical University of Denmark (DTU) near Copenhagen. Using data from multiple satellites, including the European Space Agency's (ESA) three Swarm satellites launched in 2013, this project is trying to figure out what is causing the SAA.

'This is a region where we see that satellites consistently (experience) electronic failures,' said Prof. Finlay. 'And we don't understand where this weak field region is coming from, what's producing it, and how it might change in the future.'

Scientists first noticed the SAA in the 1950s, and since then it has decreased in strength by a further 6%, as well as moving closer to the west. '(There) hasn't really been any convincing explanation of it,' said Prof. Finlay, adding that scientists haven't been able to predict how it's going to alter.

The CoreSat project is hoping to change all that, using the most detailed data available yet to study the properties of the magnetic field here and how it shifts over time. By probing the SAA, the team are hoping to see what's going on inside Earth's core that might be causing it.

One possibility is that there could be a vast anticyclone in the southern portion of Earth's liquid metal outer core, which may be pushing out the magnetic field from the South Atlantic region. Another possibility is that the magnetic field in this region is pointing the wrong way – in effect, there's a mini-polarity reversal taking place.

The SAA gives us a direct look at how a weakened magnetic field can affect satellites, as numerous spacecraft have reported electronic malfunctions when flying over this region as they are hit by . But it's unclear at the moment if the SAA has any relation to the Earth's magnetic field flipping in polarity, which is also something Prof. Finlay and his team will investigate.

'In some simulations you see features like the SAA growing during a pole reversal,' he said. 'It's not necessarily the case, but it wouldn't be a surprise if something like this was involved in a magnetic reversal.'

A glimpse

Nevertheless, the SAA just might give us a glimpse of what is to come in the near future. If trends continue, our planet's magnetic field could reverse again in one or two millennia. Prior to that, the field may continue to weaken, and within a century we could be faced with serious problems.

'The decrease in geomagnetic field is much more important and dramatic than the reversal,' said Dr. Thouveny. 'It is very important to understand if the present field will decay to zero in the next century, because we will have to prepare.'

Explore further: Stalagmite study offers clues about Earth's past magnetic polarity shifts

Related Stories

Earth's magnetic field is not about to reverse, study finds

April 30, 2018

A study of the most recent near-reversals of the Earth's magnetic field by an international team of researchers, including the University of Liverpool, has found it is unlikely that such an event will take place anytime soon.

Video: Magnetic field update

June 20, 2014

This animation shows changes in Earth's magnetic field from January to June 2014 as measured by ESA's Swarm trio of satellites.

Recommended for you

Researchers make coldest quantum gas of molecules

February 21, 2019

JILA researchers have made a long-lived, record-cold gas of molecules that follow the wave patterns of quantum mechanics instead of the strictly particle nature of ordinary classical physics. The creation of this gas boosts ...

Sculpting stable structures in pure liquids

February 21, 2019

Oscillating flow and light pulses can be used to create reconfigurable architecture in liquid crystals. Materials scientists can carefully engineer concerted microfluidic flows and localized optothermal fields to achieve ...


Adjust slider to filter visible comments by rank

Display comments: newest first

1.8 / 5 (10) Dec 07, 2018
These people must be following the "Suspicious Observers" community.
1 / 5 (10) Dec 07, 2018
Global Magnetism Movement must be started, we need to start protesting, marching, TAXING, of course man is somehow responsible, we need to have political debates, blame Republicans because their practices deplete the magnetic particles from the earths core. Americans benefit most from the magnetic poles, we have more compasses than anyone so of course we're sucking up all the magnetic force, we need to subsidize the poor neutral non magnetized countries.
2.6 / 5 (7) Dec 07, 2018
Earth's magnetic poles could start to flip. What happens then?

Homing pigeons get lost?

These people must be following the "Suspicious Observers" community.

Nobody with any brains follows that fruitloop crankery.
not rated yet Dec 07, 2018
First, our communications satellites in the highest orbits go down.

I wonder how all the satellites sent to Mars, Jupiter, Pluto,... communicate? They are all far beyond earth's magnetosphere.
5 / 5 (4) Dec 08, 2018
Doesn't make sense. It's nonsense to predict it to reach 0 in the next century based on observations that it took 3000 years to decrease by 30%, i.e. 0.1% per century. Some misquoting or exaggeration going on.

It doesn't follow it will keep going anyway. Could level off or turn back to a higher value. They say themselves they don't know what it will do next.

And if it does reach 0, yes we need to take precautions but it's not disastrous for us. It means we have to make space hardy satellites, avoid flying passenger flights across the North Pole, and have solar storm shelters in space stations. And after decades or centuries of this the ozone layer is depleted by solar storms, and we need more sunblock cream to protect ourselves from skin cancer, and also migrating
birds could get confused.
5 / 5 (4) Dec 08, 2018
Doesn't make sense. It's nonsense to predict it to reach 0 in the next century based on observations that it took 3000 years to decrease by 30%, i.e. 0.1% per century. Some misquoting or exaggeration going on.

Hello, author here. Sorry if that's a bit confusing, he's implying that the field could decay more within the next century. And he's saying in the final quote that we'll need to prepare more in the coming century, not that it will descend to zero in a century if current trends continue.
not rated yet Dec 08, 2018
What influence does this have on mutation rates. We may need to recalibrate dating of lifeforms as a result.
Da Schneib
1 / 5 (1) Dec 09, 2018
Who cares? By the time this is a problem there won't be a billion humans left on the planet.
1 / 5 (1) Dec 10, 2018
It's Trump's fault! Impeach! Hillary, save us!
Da Schneib
1 / 5 (1) Dec 10, 2018
I am irresistibly reminded of a cartoon from the time of the Chernobyl disaster in my local paper. The picture is of a newscaster, with a background of Silicon Valley with dark nasty clouds raining over it; the caption is, "Scientists believe that the radiation from the exploding nuclear reactor will have little effect on the Valley's toxic ground water."
not rated yet Dec 10, 2018
Place a Satellite at a Geostationary orbit that generates a man-made field....problem solved.
Whydening Gyre
not rated yet Dec 10, 2018
"Earth's magnetic poles could start to flip. What happens then?"
Invest in new compass manufacturers...
not rated yet Dec 15, 2018
Place a Satellite at a Geostationary orbit that generates a man-made field....problem solved.

Place a Satellite at a Geostationary orbit that generates a man-made field....problem solved.

Easily said than done. With our present technology, this idea is not engineerable

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.