A new study reveals that a reversal of the Earth’s magnetic poles 42,000 to 41,000 years ago may have sparked environmental crises leading to mass extinctions. The period becomes the Laschamps excursion and research used precise radiocarbon dating obtained from ancient tree fossils to study its effects.
The team explains how they created an accurate radiocarbon record around the time of the “Laschamps geomagnetic reversal, about 41,000 years ago, of the rings of New Zealand swampauri trees.”
“This record reveals a significant increase in the carbon-14 content of the atmosphere, culminating in the period of declining magnetic field strength prior to the polarity switch.” The team concluded that the “minimum geomagnetic fields caused significant changes in atmospheric ozone concentrations that synchronously caused global climate and environment” with their model examining the consequences of this event.
The researchers also emphasized that it is the first study of its kind to determine a link between polar reversals and changes in the environment. To conduct the study, Cooper and his team used cross-sections of four old trees taken from a swamp near 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 patterns. Their results indicated that the increase in charged particles entering the atmosphere would also result in an increase in the production of hydrogen and nitrogen oxides in the atmosphere.
These molecules would consume ozone and prevent the stratospheric ozone from protecting the inhabitants of the Earth from ultraviolet radiation. These changes would also disrupt sunlight from being absorbed from different layers of the atmosphere, leading to a large-scale cooling of the planet.
Although the research is generally interesting and solid, the researchers rely a little too much on hypotheses. It’s as if they’re looking for something that happened 42,000 years ago that may be related to changing environmental conditions.
What ultimately happened 42,000 years ago is still unknown. But the work could inspire more research to explore the principles behind these mass extinctions. The study has been published in the journal Science
DISCLAIMER: This article has been updated to contextualize the limitations of the study and its conclusions.