A new study reveals that an investment in the Earth’s magnetic poles 42,000 to 41,000 years ago may have caused environmental crises that led to mass extinctions. The period is called Excursion to Laschamps and the research used accurate carbon dating obtained from ancient tree fossils to study their effects.
The team details how they created an accurate radiocarbon record around the “Laschamps geomagnetic reversal about 41,000 years ago from the rings of kauri trees in the New Zealand swamp.”
“This record reveals a substantial increase in the carbon 14 content of the atmosphere that culminates during the period of weakening of the magnetic field strength prior to the polarity switch.” The team concluded that the “minimum of the geomagnetic field caused substantial changes in atmospheric ozone concentration that led to the synchronous global climate and environment,” with its model investigating the consequences of this event.
The researchers also noted that it is the first study of its kind to determine a link between dust investment and environmental change. To conduct the study, Cooper and his team used cross-sections of four ancient trees recovered from a Ngāwhā Springs swamp in northern New Zealand and tested them for carbon-14.
The team then simulated how a changing magnetic field could affect atmospheric weather patterns. Their results indicated that the increase in charged particles entering the atmosphere would also result in an increase in the production of atmospheric hydrogen oxides and nitrogen.
These molecules would consume ozone, preventing stratospheric ozone from protecting Earth’s inhabitants from ultraviolet radiation. These changes would also alter the absorption of sunlight into different layers of the atmosphere, leading to large-scale cooling of the planet.
However, while the research is generally interesting and solid, researchers rely too heavily on hypotheses. It’s as if they’re looking for everything that happened 42,000 years ago that could possibly be related to changing environmental circumstances.
In the end, it is still unknown what happened 42,000 years ago. But the work could inspire more research to examine the principles behind these mass extinctions. The study was published in the journal Science.
DISCLAIMER: This article was updated to contextualize the limitations of the research and its findings.