Ancient relic points to a turning point in Earth's history 42,000 years ago

Full article issued by The University of New South Wales.

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 ARC-supported 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.

'For the first time ever, we have been able to precisely date the timing and environmental impacts of the last magnetic pole switch,' says Professor Chris Turney, an Australian Laureate Fellow 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. 

But the researchers have now been able to create a detailed timescale of how Earth’s atmosphere changed over this time by analysing rings on the ancient kauri trees.

The event has now been dubbed 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.

 

UNSW’s Professor Chris Turney at the Chronos 14Carbon - Cycle facility. Image Credit: UNSW Sydney.