Palaeontology

Geomagnetic reversal linked to mass extinction

By T.K. Randall
February 21, 2021

Image: Compass
Credit: Shyamal / CC BY-SA 3.0 (adapted) The current orientation of our planet's magnetic field is something that we tend to take for granted, however every now and again the Earth's poles perform a total reversal, meaning that at some point in the future we can expect the same thing to happen again.

But what was the impact of life on Earth the last time this happened ?

According to new research, when the Earth's magnetic field flipped around 42,000 years ago it caused so much environmental destruction that it could explain the disappearance of much of the planet's megafauna as well as the Neanderthals - our closest living relatives at that time.

While previous studies had suggested that this event - known as the Laschamps excursion - had little impact on life, scientists now believe that the opposite is more likely to have been true.

The research involved conducting radiocarbon analyses of ancient kauri trees (which date back up to 42,000 years) that were found preserved in the northern wetlands of New Zealand.By cross-referencing their findings with other scientific data such as that obtained from ice core samples, they were able to identify a period of significant environmental upheaval across the globe.

"We see this massive growth of the ice sheet over North America... we see tropical rain belts in the west Pacific shifting dramatically at that point, and then also wind belts in the southern ocean and a drying out in Australia," the researchers wrote.

That said, not all scientists agree with the study's conclusions.

"I think it could certainly have contributed to the [Neanderthals'] demise," said Chris Stringer from the Natural History Museum in London.

"But they did survive longer and ranged more widely than just Europe, and we have a very poor fix on the timing of their final disappearance across swathes of Asia."

Source: The Guardian

Tags: Earth, Magnetic