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Earth’s magnetic field protects us, acting as a shield against the solar wind (a flow of charged particles and radiation) that flows from the sun. But the geomagnetic field is not stable in strength and direction, and it has the ability to turn or reverse.
About 42,000 years ago, during an event known as the Laschamp Excursion, the Poles did just that for about 800 years, before turning back the clock – but scientists weren’t sure exactly how or if this had happened. had an impact on the world.
Now, a team of researchers from the University of New South Wales in Sydney and the South Australian Museum claim that the reversal, along with changing solar winds, could have triggered a series of dramatic climate changes leading to environmental changes and to massive extinctions.
Scientists analyzed the rings found in ancient New Zealand kauris, some of which had been preserved in sediments for over 40,000 years, to create a timescale of how the Earth’s atmosphere has changed over time. .
Using radiocarbon dating, the team studied cross sections of trees – whose annual growth rings served as a natural timestamp – to track changes in radiocarbon levels during pole reversal.
“Using the ancient trees, we were able to measure and date the peak in atmospheric radiocarbon levels caused by the collapse of the Earth’s magnetic field,” Chris Turney, professor at UNSW Science, director of the Earth and Sustainability Science Research Center at university and co-lead author of the study, said in a statement.
The team compared their new timescale with records from cave, ice core and bog sites around the world.
‘End of days’
The researchers found that the reversal led to “pronounced climate change”. Their modeling showed that the growth of the ice sheet and glaciers in North America and the changes in major wind belts and tropical storm systems could be traced back to the period of the magnetic pole switch, which scientists called it “the Adams event”.
“Sure enough, Earth’s magnetic field is almost gone, and it opened up the planet to all these high energy particles from outer space. It would have been an incredibly scary time, almost like the end of days,” said Turney.
Researchers say the Adams event could explain many mysteries of Earth’s evolution, including the extinction of the Neanderthals and the sudden and widespread appearance of figurative art in caves around the world.
The phenomenon would have led to dramatic and dazzling events. In the run-up to the Adams event, the Earth’s magnetic field dropped to just 0% to 6% of its force, while the Sun has experienced several long periods of calm solar activity.
“We had virtually no magnetic field – our shield of cosmic radiation was totally gone,” Turney said.
The weakening magnetic field meant that more space weather conditions, such as solar flares and galactic cosmic rays, could be heading towards Earth.
“Unfiltered radiation from space tore up particles of air in Earth’s atmosphere, separating electrons and emitting light – a process called ionization,” Turney said in a statement. “Ionized air has ‘fried’ the ozone layer, triggering a wave of climate change across the world.”
During this time, the inhabitants of Earth would have been subjected to dazzling exposures – northern and southern lights, caused by solar winds hitting Earth’s atmosphere, would have been frequent. Meanwhile, the ionized air is said to have increased the frequency of electrical storms – which scientists say caused humans to take refuge in caves.
“The common rock art motif of the red ocher handprints may indicate that it was used as a sunscreen, a technique still used today by some groups,” said Alan Cooper, honorary researcher at the South Australian Museum, in a press release.
“The amazing images created in the caves during this period have been preserved, while other works of art in open areas have since eroded, making it appear that the art suddenly began 42,000 years ago,” added Cooper, co-lead author.
A coming reversal
“This speed – along with the weakening of Earth’s magnetic field of around 9% over the past 170 years – could indicate an upcoming reversal,” Cooper said.
“If a similar event happened today, the consequences would be enormous for modern society. The incoming cosmic radiation would destroy our power grids and our satellite networks,” he said.
Human activity has already pushed carbon into the atmosphere to levels “never seen by mankind before,” Cooper said.
“A reversal of the magnetic poles or an extreme shift in the activity of the Sun would be accelerators of unprecedented climate change. We urgently need to reduce carbon emissions before such a random event happens again,” he said. -he adds.
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