A global period of upheaval 42,000 years ago was the result of a reversal in Earth’s magnetic field flux, new research has found.
Evidence from Ancient Tree Rings
According to radiocarbon preserved in ancient tree rings, several centuries’ worth of climate breakdown, mass extinctions, and even changes in human behavior are often directly linked to the last time Earth’s magnetic flux changed its polarity.
Adams Event and Earth’s Magnetic Field Flux
The research team has named the amount the Adams Transitional Geomagnetic Event, or Adams Event, after sci-fi writer Douglas Adams, who famously declared the amount 42 the last word answer to life, the Universe, and everything.
“For the primary time ever, we’ve been ready to precisely date the timing and environmental impacts of the last magnetic pole switch,” said Earth scientist Chris Turney of the University of latest South Wales in Australia.
Evidence from New Zealand kauri trees
“The findings were made possible with ancient New Zealand kauri trees, which are preserved in sediments for over 40,000 years. Using the traditional trees we could measure, and date, the spike in atmospheric radiocarbon levels caused by the collapse of Earth’s magnetic flux .”
This most up-to-date period of magnetic reversal is understood because of the Laschamp event, and it’s what we call a geomagnetic excursion. this is often when the planet’s magnetic poles briefly swap places before returning to their original positions. It’s one among the foremost well studies of Earth’s magnetic flux events, recorded by ferromagnetic minerals.
It happened around 41,000 years ago and lasted for around 800 years. Exactly what impact this event had on life on the earth was unclear, though – so when scientists uncovered an ancient kauri tree (Agathis australis) in 2019 that had been alive during this point period, they seized on the prospect to find out more.
That’s because trees record atmospheric activity in their annual growth rings. especially, carbon-14, or radiocarbon, can reveal tons of data about the celestial activity.
Radiocarbon only occurs on Earth in trace amounts compared to the opposite present carbon isotopes. It’s formed within the upper atmosphere under the bombardment of cosmic rays from space. When these rays enter the atmosphere, they interact with the local nitrogen atoms to trigger a natural process that produces radiocarbon.
Since cosmic rays are constantly streaming through space, Earth receives a more or less steady supply of radiocarbon. Therefore, a spike in radiocarbon in tree rings tells us that Earth had greater exposure to radiocarbon during that year.
When Earth’s magnetic flux is weakened, because it was during the Laschamp event, more cosmic rays penetrate through to the atmosphere to supply more radiocarbon. due to this, scientists had previously been ready to ascertain that Earth’s magnetic flux had weakened to about 28 percent of its normal strength during that 800-year period.
The kauri tree, however, allowed the research team to review the years leading up to the Laschamp event. They found that the Adams event happened about 42,200 years ago, and therefore the magnetic flux was at its weakest point before the Laschamp event.
“Earth’s magnetic flux dropped to only 0-6 percent strength during the Adams Event,” Turney explained. “We essentially had no magnetic flux in the least – our radiation shield was totally gone.”
During this point, the Sun’s magnetic flux would even have weakened several times, as it, too, experienced magnetic reversal as a part of its regular cycle. These periods see less sunspot and flare activity, but the Sun’s magnetic flux also provides Earth with a measure of protection from cosmic rays – so, during these solar minima, ionizing radiation bombardment would have increased again.
This weakened magnetic flux would have triggered substantial changes in Earth’s atmospheric ozone, with dramatic consequences, including electrical storms and spectacular aurorae, and global climate change around the world.
“Unfiltered radiation from space ripped apart air particles in Earth’s atmosphere, separating electrons and emitting light – a process called ionization,” Turney said.
“The ionized air ‘fried’ the ozonosphere, triggering a ripple of global climate change across the world .”
This is according to climate and environmental changes from this point observed in other records from across the world, like the mysterious extinction of Australia’s megafauna.
Curiously, it also coincides with a number of our oldest cave art on record, prompting the researchers to hypothesize that the Adams Event could have driven humans indoors.
“This sudden behavioral shift in very different parts of the planet is according to an increasing or changed use of caves during the Adams Event, potentially as shelter from the rise of ultraviolet B, potentially to harmful levels, during grand solar minima of solar energetic particles, which could also explain an increased use of red ochre sunscreen,” they wrote in their paper.
That’s somewhat speculative, of course, but it suggests that a geomagnetic reversal is often a seriously world-altering event. and up-to-date evidence has suggested that we’re currently on the verge of another.
This, the researchers say, might be absolutely disastrous within the current climate.
“Our atmosphere is already crammed with carbon at levels never seen by humanity before. A magnetic pole reversal or extreme change in Sun activity would be unprecedented global climate change accelerants,” Turney said.
“We urgently got to get carbon emissions down before such a random event happens again.”