Some 42,000 years ago, the reversal of the Earth's magnetic field disrupted the climate, leading to extinction events and long-term changes in the behavior of human ancestors.
This is what emerges from the study published in the journal Science by the group of the Australian University of New South Wales coordinated by Chris Turney.
The research is based on the study of the radioactive decay of carbon, the so-called radiocarbon analysis, in the growth rings of the millennial kauri trees of New Zealand.
These are trees of impressive size, which can reach 50 meters in height and exceed 10 meters in circumference, like the Californian sequoias.
Thanks also to the help of climate models, the authors have, in particular, found a significant increase in atmospheric radiocarbon during the period of weakening of the magnetic field intensity that preceded the polarity reversal.
“We knew that 42,000 years ago the Earth underwent various environmental upheavals, but we did not know the reasons.
Now - observes Turney - we can accurately date the inversion of the magnetic field thanks to the traces left in the geological history of the planet ”.
According to the expert, "today we know that a similar event would almost certainly cause chaos with modern electronic and satellite technologies, but the potential environmental impacts of a magnetic reversal are still largely unknown."
For this, Turney concludes, the study of the Earth's climatic history "offers one of the best opportunities to analyze the potential future impacts of extreme changes in the planet's magnetic field".
