This dramatic turning point in Earth’s history—laced with electrical storms, widespread auroras, and cosmic radiation—was triggered by the reversal of Earth’s magnetic poles and changing solar winds. The temporary breakdown of Earth's magnetic field 42,000 years ago sparked major climate shifts that led to global environmental change and mass extinctions, a new international study co-led by UNSW Sydney and the South Australian Museum shows.
This dramatic turning point in Earth's history—laced with electrical storms, widespread auroras, and cosmic radiation—was triggered by the reversal of Earth's magnetic poles and changing solar winds.
The researchers dubbed this danger period the 'Adams Transitional Geomagnetic Event', or 'Adams Event' for short—a tribute to science fiction writer Douglas Adams, who wrote in The Hitchhiker's Guide to the Galaxy that '42' was the answer to life, the universe, and everything.
The findings are published today in Science.
"For the first time ever, we have been able to precisely date the timing and environmental impacts of the last magnetic pole switch," says Chris Turney, a professor at UNSW Science and co-lead author of the study.
"The findings were made possible with ancient New Zealand kauri trees, which have been preserved in sediments for over 40,000 years.
"Using the ancient trees we could measure, and date, the spike in atmospheric radiocarbon levels caused by the collapse of Earth's magnetic field."
While scientists already knew the magnetic poles temporarily flipped around 41-42,000 years ago (known as the 'Laschamps Excursion'), they didn't know exactly how it impacted life on Earth—if at all. % buffered
The temporary breakdown of Earth’s magnetic field 42,000 years ago sparked major climate shifts that led to global environmental change and mass extinctions. Credit: UNSW Sydney
But the researchers were able to create a detailed timescale of how Earth's atmosphere changed over this time by analysing rings on the ancient kauri trees.
"The kauri trees are like the Rosetta Stone, helping us tie together records of environmental change in caves, ice cores and peat bogs around the world," says co-lead Professor Alan Cooper, Honorary Researcher at the South Australian Museum.
The researchers compared the newly-created timescale with records from sites across the Pacific and used it in global climate modelling, finding that the growth of ice sheets and glaciers over North America and large shifts in major wind belts and tropical storm systems could be traced back to the Adams Event.
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