Lessons from the Laschamps Excursion 42,000 years ago

By | May 28, 2023

Dirk Schulze-Makuch writes:

After studying the reversal of Earth’s magnetic pole known to have occurred 42,000 years ago, a science team led by Alan Cooper from the South Australian Museum in Adelaide, Australia concludes that the event had significant environmental repercussions, especially at lower and mid-latitudes. That time period, known as the Laschamps Excursion, had anomalously high radiocarbon concentrations in the atmosphere, which were linked to a higher influx of radiation. When the reversal occurred, within a span of about 1,000 years, Earth’s magnetic field weakened drastically and the magnetic North and South Poles flipped, temporarily leaving surface-dwelling organisms largely unprotected from high influxes of both ionic and ultraviolet radiation.

Previous studies had not found much of an environmental impact from the flip. But that conclusion was based primarily on ice cores from Greenland and Antarctica, which biased it toward higher latitudes. Cooper and his colleagues took more representative samples from all over the world, including from tree rings in New Zealand. They conclude that the magnetic reversal was in fact related to the extinction of a large fraction of large animals at the time, as well as the disappearance of the Neanderthals and even the appearance of cave art.

If the connection with mass extinctions is true, it’s a cause for concern. Earth’s magnetic field has weakened nearly 10 percent in the last 200 years, and the position of the magnetic North Pole has changed quite a bit. A magnetic reversal may be imminent. One can only imagine what trouble such an event could cause, with more solar and cosmic radiation hitting Earth’s surface. Potentially, we could see an increase in cancer rates, environmental disturbances, and the failure of power grids. Do we need to worry? [Continue reading…]

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