19 FEBRUARY 2021
A global period of upheaval 42,000 years ago was the result of a reversal in Earth s magnetic field, new research has found.
According to radiocarbon preserved in ancient tree rings, several centuries worth of climate breakdown, mass extinctions, and even changes in human behaviour can be directly linked to the last time Earth s magnetic field changed its polarity.
The research team has named the period the Adams Transitional Geomagnetic Event, or Adams Event, after sci-fi writer Douglas Adams, who famously declared the number 42 the ultimate answer to life, the Universe, and everything. For the first time ever, we have been able to precisely date the timing and environmental impacts of the last magnetic pole switch, said Earth scientist Chris Turney of the University of New South Wales in Australia.
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But according to the team s findings, the most dramatic part was the lead-up to the reversal, when the poles were migrating across the Earth. Earth s magnetic field dropped to only 0 to 6 per cent strength during the Adams Event, said Professor Turney. We essentially had no magnetic field at all – our cosmic radiation shield was totally gone.
During the magnetic field breakdown, the Sun experienced several grand solar minima (GSM) – long-term periods of quiet solar activity.
Even though a GSM means less activity on the Sun s surface, the weakening of its magnetic field can mean more space weather – like solar flares and galactic cosmic rays – could head Earth s way.
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Stromatolites – fossils of earliest life on Earth – may owe existence to viruses
As the Mars Rover sets out to look for evidence of life on another planet, scientists back on Earth suggest viruses played a key role in creating stromatolites, our planet’s earliest lifeforms.
Stromatolites at Shark Bay, Western Australia. Photo: UNSW Sydney/Brendan Burns
It may pain us to hear this during a deadly viral pandemic, but life as we know it on this planet may never have occurred if it weren’t for viruses, scientists studying billion-year-old ‘living rocks’ say.
In a paper published in the March issue of Trends in Microbiology, a team of scientists from UNSW Sydney and the US looked at evidence of the world’s oldest lifeforms in fossils known as stromatolites, layered limestone rocks often found in shallow waters around the globe. They wanted to understand the mechanism that led colonies of single-celled organisms known as microbial mats to create these intriguin