A global period of revolution 42,000 years ago was the result of a reversal in the Earth’s magnetic field, new research has found.
According to radiocarbon conservation in ancient tree rings, climate disruption, mass extinctions, and even changes in human behavior of several centuries can be directly linked to the last time the Earth’s magnetic field changed polarity.
The research team named the period the Adams Transitional Geomagnetic Event, or Adams Event, after science writer Douglas Adams, who declared the number 42 as the ultimate answer to life, the universe and everything.
“For the first time ever, we were able to precisely update the timing and environmental impacts of the latest magnetic pole switch,” said Chris Turney of the Earth Scientist at the University of New South Wales in Australia.
“The findings were made possible by ancient New Zealand kauri trees, which have been preserved in sediments for more than 40,000 years. Using the ancient trees, we were able to measure and date the increase in atmospheric radiocarbon levels caused by the collapse of the Earth’s magnetic field. “
This most recent period of magnetic reversal is known as the Laschamp event, and this is what we call a geomagnetic outing. This is when the magnetic poles of the planet change places briefly before returning to their original positions. This is one of the most studied events of the Earth’s magnetic field, recorded by ferromagnetic minerals.
It occurred about 41,000 years ago and lasted about 800 years. Exactly what impact this event had on life on the planet was unclear, however – so when scientists discovered an ancient kauri tree (Agathis australis) in 2019 who lived during this period, they took the opportunity to learn more.
This is because trees absorb atmospheric activity in their annual growth rings. In particular, carbon-14, or radiocarbon, can reveal a lot of information about celestial activity.
Radiocarbon occurs only in trace amounts on Earth compared to the other naturally occurring carbon isotopes. It is formed in the upper atmosphere under the bombardment of cosmic rays from space. When these rays enter the atmosphere, it interacts with the local nitrogen atoms to cause a nuclear reaction that produces radiocarbon.
As cosmic rays constantly flow through space, the earth receives more or less steady supply of radiocarbon. Therefore, an increase in radiocarbon in tree rings tells us that the earth had greater exposure to radiocarbon during that year.
When the Earth’s magnetic field is attenuated, as during the Laschamp event, more cosmic rays penetrate the atmosphere to produce more radiocarbon. As a result, scientists were able to determine earlier that the Earth’s magnetic field weakened to about 28 percent of its normal strength over a period of 800 years.
However, the kauri tree enabled the research team to study the years before the Laschamp event. They found that the Adams event occurred about 42,200 years ago, and that the magnetic field was at its weakest point previously the Laschamp meeting.
“The Earth’s magnetic field dropped to just 0-6 percent strength during the Adams event,” Turney explained. “We actually had no magnetic field – our cosmic radiation shield was completely gone.”
During this time, the magnetic field of the Sun would also have weakened several times, as it also experienced magnetic reversal as part of its regular cycle. These periods exhibit less sunspot and torch activity, but the sun’s magnetic field also provides some protection against cosmic rays on Earth – so cosmic ray bombardment would have increased again during this minimum of the sun.
This weakened magnetic field would have caused significant changes in the Earth’s atmospheric ozone, with dramatic consequences, including electric storms and spectacular aurorae, and climate change around the world.
“Unfiltered radiation from space has torn apart air particles in the Earth’s atmosphere, separated electrons and emitted light – a process called ionization,” Turney said.
“The ionized air ‘fried’ the ozone layer, which caused a ripple of climate change around the world.”
This is in line with climate and environmental changes of this time observed in other reports from around the world, such as the mysterious extinction of the Australian megafauna.
Oddly enough, it also coincides with some of our oldest cave art recorded, prompting researchers to assume that the Adams Event could have driven people indoors.
‘This sudden shift in behavior in many different parts of the world corresponds to an increasing or changing use of caves during the Adams event, possibly as a shelter against the increase of ultraviolet B, possibly to harmful levels, during small-minima or solar energy particles that can also explain an increase in the use of red ocher sunscreen, ‘they write in their newspaper.
This is of course somewhat speculative, but it does suggest that a geomagnetic reversal could be a serious world-changing event. And recent evidence has suggested that we are currently on the verge of being different.
This, according to the researchers, could be absolutely disastrous in the current climate.
“Our atmosphere is already filled with carbon at levels that humanity has never seen before. A reversal of the magnetic pole or extreme change in solar activity would be an unprecedented climate change,” Turney said.
“We urgently need to reduce carbon emissions before such a random event happens again.”
The research was published in Science.