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A new study reveals that a reversal of the Earth’s magnetic poles 42,000 to 41,000 years ago may have led to environmental crises that resulted in mass extinctions. The period is called the Laschamps excursion and research used precise carbon dating obtained from ancient tree fossils to study its effects.
The team details how they created an accurate radiocarbon record at the time of the “Laschamps geomagnetic reversal about 41,000 years ago from rings of kauri trees in New Zealand swamps.”
“This record reveals a substantial increase in the carbon-14 content of the peak atmosphere during the period of weakening magnetic field strength preceding the change in polarity.” The team concluded that “the minimum geomagnetic field caused substantial changes in atmospheric ozone concentration which drove the synchronous global climate and the environment” with their model investigating the consequences of this event.
The researchers also pointed out that this was the first study of its kind to determine a link between pole reversals and environmental changes. To conduct the study, Cooper and his team used cross-sections of four ancient trees recovered from a swamp in Ngāwhā Springs in northern New Zealand and tested them for carbon-14.
The team then simulated how a changing magnetic field could affect atmospheric weather conditions. Their results indicate that the increase in charged particles entering the atmosphere would also lead to an increase in the production of atmospheric hydrogen and nitrogen oxides.
These molecules would consume ozone, preventing stratospheric ozone from protecting Earth’s inhabitants from ultraviolet radiation. These changes would also prevent sunlight from being absorbed in different layers of the atmosphere, leading to large-scale cooling of the planet.
However, while the research is generally interesting and solid, researchers rely a little too much on guesswork. It is as if they are researching everything that happened 42,000 years ago that could be related to changing environmental circumstances.
Ultimately, what happened 42,000 years ago is still unknown. But the work could inspire more research to examine the principles behind these massive extinctions. The study was published in the journal Science.
DISCLAIMER: This article has been updated to contextualize the limitations of the research and its findings.
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