Feb 20, 2021 - Science

When the Earth's magnetic poles flipped out

The aurora borealis — which results from disturbances in the Earth's magnosphere caused by solar winds — seen above Murmansk, Russia, last month.
The aurora borealis — which results from disturbances in the Earth's magnosphere caused by solar winds — seen above Murmansk, Russia, last month. Photo: Lev Fedoseyev\TASS via Getty Images

The Earth's magnetic poles temporarily reversed themselves 42,000 years ago, triggering environmental catastrophe, according to a new study.

Why it matters: The research sheds new light on a period of chaotic climatic change and human upheaval — and provides a warning that the same thing could happen to us.

Driving the news: In a study published Thursday in Science, researchers analyzed the rings found in ancient kauri trees in New Zealand to produce a radiocarbon archive.

  • The tree ring data shows that nearly 42,000 years ago, the Earth's geomagnetic field flipped and stayed reversed for some 800 years before returning to normal.

What happened: Scientists knew that the reversal — called the Laschamp Excursion — had happened, but the new study provides a more accurate time frame.

  • It also shows just how catastrophic the event likely was for the Earth and those living on it, including humans and their evolutionary cousins the Neanderthals.
  • With virtually no protective magnetic field, and with solar activity at an ebb, the planet was bombarded with high-energy particles from outer space, leading to rapid climate change and spectacular electrical storms.
  • It would have been "like the end of days," said Chris Turney, an Earth scientist at the University of New South Wales and a lead co-author on the paper, in a statement.

What's next: Earlier research has indicated that the Earth's magnetic north pole has been moving at an accelerating pace, which could presage another reversal.

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