Environment

Ancient tree tells chaotic tale of Earth’s magnetic field reversal

Ancient tree tells chaotic tal...
An ancient kauri tree log from Ngāwhā, New Zealand
An ancient kauri tree log from Ngāwhā, New Zealand
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Handprints in red ochre – which may have been used as an ancient form of sunscreen – are a common cave art motif. The centre of this cave art from Spain is believed to be almost 42,000 years old.
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Handprints in red ochre – which may have been used as an ancient form of sunscreen – are a common cave art motif. The centre of this cave art from Spain is believed to be almost 42,000 years old.
An ancient kauri tree log from Ngāwhā, New Zealand
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An ancient kauri tree log from Ngāwhā, New Zealand
Another look at the ancient tree unearthed in New Zealand
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Another look at the ancient tree unearthed in New Zealand
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A perfectly preserved ancient tree fossil has offered scientists a unique peek into a moment 42,000 years ago when the Earth’s magnetic field went haywire. The impressive study paints a picture of temporary environmental chaos, potentially influencing everything from an increase in cave paintings to the extinction of the Neanderthals.

Without the Earth’s magnetic field we’d have a pretty hard time living on the planet. Beyond helping us simply navigate around the world with a compass, the Earth’s magnetic field is fundamental to the existence of life. It helps deflect harmful solar winds and keeps our protective atmosphere in place.

But our planet’s magnetic field is far from static. In fact, it is profoundly dynamic, consistently shifting and fluctuating over time. Every few hundred thousand years it completely flips, with magnetic north switching places with magnetic south.

The last major geomagnetic reversal occurred 780,000 years ago, and plenty of scientists suggest we are well overdue for a similar event. In between these full geomagnetic reversals, which can last up to 10,000 years, we find shorter disruptions to the Earth’s magnetic field. These events are known as geomagnetic excursions.

Geomagnetic excursions are short-lived, and involve temporary changes to the Earth’s magnetic field lasting anywhere from a few hundred to a few thousand years. The most recent recorded geomagnetic excursion is known as the Laschamps excursion and it took place around 42,000 years ago.

"The Laschamps Excursion was the last time the magnetic poles flipped," explains Chris Turney, co-lead author on a landmark new study investigating this transformative event. "They swapped places for about 800 years before changing their minds and swapping back again."

Scientists have known about these dramatic magnetic pole events for a long time but it’s never been clearly understood what kind of impact they have on life or the environment. That is until a few years ago, when an ancient fossilized tree was discovered in New Zealand.

Another look at the ancient tree unearthed in New Zealand
Another look at the ancient tree unearthed in New Zealand

Workers preparing a site for a new power-plant unearthed the massive kauri tree trunk, perfectly preserved for 42,000 years, with its rings offering up an incredible 1,700-year record of the Earth’s environmental conditions exactly spanning the period of the Laschamps Excursion.

"For the first time ever, we have been able to precisely date the timing and environmental impacts of the last magnetic pole switch," says Turney. "Using the ancient trees we could measure, and date, the spike in atmospheric radiocarbon levels caused by the collapse of Earth's magnetic field."

In a bold new study, published in the journal Science, the research team used the detailed radiocarbon data from the ancient tree to create a novel timeline of the Earth’s atmosphere across the period spanning the Laschamps Excursion. The team then ran a global climate model, incorporating previously gathered data from all over the world, to explore what acute effects this type of magnetic field disruption had on the environment.

Life, the Universe and Everything

The results reveal an incredibly dramatic period of environmental change, particularly in the stretch of time leading up to the few hundred years the Earth’s magnetic field was reversed. The study calculated a depleted ozone layer, higher levels of ultraviolet radiation and increased atmospheric ionization all coalesced about 42,000 years ago. In tribute to author Douglas Adams – in whose book The Hitchhiker's Guide the the Galaxy, the supercomputer Deep Thought calculates the answer to the ultimate question of life, the universe and everything is "42" – the researchers named this specific period the “Adams Transitional Geomagnetic Event.”

"The more we looked at the data, the more everything pointed to 42," says Turney. "It was uncanny.”

Alan Cooper, co-lead author on the study, suggests a number of novel environmental conditions would have appeared during the so-called Adams Event. Auroras, for example, would have been widespread across the entire planet, alongside extraordinary volumes of electrical storms due to increases in ionized air.

“Early humans around the world would have seen amazing auroras, shimmering veils and sheets across the sky,” says Cooper. “It must have seemed like the end of days.”

Handprints in red ochre – which may have been used as an ancient form of sunscreen – are a common cave art motif. The centre of this cave art from Spain is believed to be almost 42,000 years old.
Handprints in red ochre – which may have been used as an ancient form of sunscreen – are a common cave art motif. The centre of this cave art from Spain is believed to be almost 42,000 years old.

Perhaps the most controversial part of the new study is the degree of hypothetical speculations the researchers make between the Adams Event and evolution of life on Earth. One link raised in the study suggests the magnetic field disruption led to an influx of cave art, underpinned by the need for humans to seek shelter from the increase in ultraviolet rays.

“We think that the sharp increases in UV levels, particularly during solar flares, would suddenly make caves very valuable shelters,” suggests Cooper. “The common cave art motif of red ochre handprints may signal it was being used as sunscreen, a technique still used today by some groups.”

Other bold speculations in the study are that the Adams Event both prompted the extinction of several megafauna species in Australia and hastened the end for Neanderthals. Chris Stringer, from the Natural History Museum of London, calls the new study important but also questions some of its broad hypotheses.

“The authors also make a link with the physical extinction of the Neanderthals around 40,000 years ago and I think it could certainly have contributed to their demise,” he said in an interview with The Guardian. “But they did survive longer and ranged more widely than just Europe, and we have a very poor fix on the timing of their final disappearance across swathes of Asia.”

Shifting to what the research can tell us about life on Earth today, Alan Cooper cautiously suggests his team’s research offer novel insights into how the world would be affected if something like the Adams Event were to happen nowadays. He points to current movements of the north magnetic pole across the Northern Hemisphere as a potential warning sign.

"This speed – alongside the weakening of Earth's magnetic field by around nine per cent in the past 170 years – could indicate an upcoming reversal," says Cooper. "If a similar event happened today, the consequences would be huge for modern society. Incoming cosmic radiation would destroy our electric power grids and satellite networks."

The new study was published in the journal Science, and the short video below narrated by Stephen Fry gives an overview of the Adams Event.

Paleopocalypse! - Narrated by Stephen Fry.

Source: UNSW

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18 comments
18 comments
Chris Coles
Am currently reading; More Evidence of Rapid Geomagnetic Reversals Confirms a Young earth by Dr. Andrew A. Snelling, which sets out an alternative debate regarding the time scale for such a reversal . . . of months rather than thousands of years.

Then add, we already know these reversals regularly occur; so we can also take it as read that the majority of species survive. On a more personal level, my skull has a strong protruding rib from forehead to the back of the upper surface; strongly suggesting that I may have Neanderthal DNA within my body . . . which also means that, perhaps, everyone should accept that instead of their being made extinct; they have simply become a part of a deeper relationship with Homo Sapiens.
drBill
Is the trunk an example of mummified wood, so there's still carbon in it? Is the age determined by carbon dating?
poika
The magnetic field has been known to be unreliable for years. To locate the position of transmitters of radio signals on earth, the receiving antennae have to be oriented to the North Star as a reliable true North for all radio signal locations. The magnetic north continues to wander and is unreliablewhen the changes occur.
Rhino Jones
The article describes the tree as fossilized, but doesn't state that it was petrified, rather that it was preserved, which one takes to mean it was not in fact fossilized. If the wood wasn't replaced by silica, then it was not fossilized.
Bill Hunt
These events are nothing new and very doubtful were a life changing event in comparison to volcanic and other geo thermo events. But who can say with any certainty. One thing is very clear that our world is more fragile than we realize and humans do little to help
akarp
I wonder if the magnetic field flips because the core is rotating and the Janibekov’s effect?
akarp
While a magnetic flip is unlikely to cause issues with life, our human world would go nuts for a while. "The whole would end like Y2K!" There would be quite a bit of corrections to make though.
clay
You had me at: "The more we looked at the data, the more everything pointed to 42," says Turney. "It was uncanny."

:-) That's about all there is to say about that.

Okay, one more thing: This singular buried treesure (<< should be a word) demonstrates how [such as in a republic for which even ONE vote can still make a difference] every single artifact is a treasure... to be cherished for historical record keeping in all it's dimensions. Because one never knows what informational treasure it may yield.
bwana4swahili
Yet another way for Mother Nature to rid the Earth of us pests... :) :)
LauchlanGiddy
Our civilisation survives on an exceptionally thin knife edge, we dont realise it, but an event like this would be an extinction level event for our civilisation, not necessarily civilisation. ONE major system failure or major impact would have a domino effect that would be catastrophic. we had isolated populations with low technology and very very low numbers, we have BILLIONS now , are overpopulated , and live hand to mouth in exceptionally high tech cities.....i dont need to spell out how it would end.