March 2, 2021

A magnetic inversion caused great extinctions 42,000 years ago


Image of the Earth seen from space

Image of the Earth seen from space
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The Earth’s history suffered a turning point 42,000 years ago, when a reversal of the magnetic poles produced a temporary magnetic field breakdown, which caused major global environmental changes and mass extinctions, according to a study published in ‘Science’.

Research from the Australian University of New South Wales (NSSW) and the South Australian Museum indicates that this event was caused by the inversion of the Earth’s magnetic poles combined with the change of the solar winds, which produced electrical storms, widespread auroras, and cosmic radiation.

The first human beings who had to live that moment were “it must have seemed like the end of days“said one of the authors, Alan Cooper of the South Australian Museum. The researchers, who dubbed this period the Adams Event, suggest that it could explain evolutionary mysteries, such as the extinction of Neanderthals or the sudden widespread appearance of figurative cave art. from around the world, having to seek more refuge.

Although scientists already knew that the magnetic poles temporarily shifted about 41-42,000 years ago (what is known as the Laschamps Event), they did not know exactly if and how it affected life on Earth. For the first time, they have been able to accurately date “the timing and environmental impacts of the last magnetic pole shift,” said study co-author Chris Turney of UNSW.

The ancient kauri trees of New Zealand, which have been preserved in sediments for more than 40,000 years, gave the team the clues, because by analyzing their rings, they were able to measure and date the peak of atmospheric radiocarbon levels caused by the collapse of the magnetic field and they created a detailed timescale of how the atmosphere changed. “Kauri trees are like the Rosetta Stone, which helps us relate records of environmental change in caves, ice cores and peatlands around the world, “explained Professor Alan Cooper of the South Australian Museum.

The researchers compared that timescale with records from locations across the Pacific and built global climate models to discover that the growth of North American ice sheets and glaciers and major changes in major wind belts and wind systems Tropical storms could be traced back to the Adams Event. One of his first clues was that the megafauna of mainland Australia and Tasmania suffered a simultaneous extinction 42,000 years ago.

The magnetic north pole – that is, the direction it points a compass needle – does not have a fixed location. It usually oscillates near the North Pole (the northernmost point on the Earth’s axis) over time due to dynamic motions within the Earth’s core, as does the magnetic south pole. Sometimes, for reasons that are not clear, the movements of the magnetic poles can be more drastic. Some 41,000-42,000 years ago they completely changed places.

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