The temporary rupture of the Earth’s magnetic field 42,000 years ago caused major climate change that led to global environmental transformations and mass extinctions.
As shown by a new international study co-led by the University of New South Wales (UNSW), Sydney and the Museum of South Australia, this dramatic turning point in Earth’s history, mixed with thunderstorms, auroras widespread and cosmic radiation, was caused by the reversal of the Earth’s magnetic poles and changing solar winds. The findings are published in Science. (Read also: Researchers get objects levitated by light).
“For the first time in history, we have been able to accurately date the timing and environmental impacts of the latest magnetic powder inversion”, Says Chris Turney, UNSW professor and lead co-author of the study.
The findings were made possible by New Zealand’s ancient kauri trees, which have been preserved in sediment for over 40,000 years. “Using ancient trees, we were able to measure and date the increase in atmospheric radiocarbon levels caused by the collapse of the Earth’s magnetic field,” Turney said in a statement.
While scientists already knew that magnetic poles were temporarily reversed 41-42,000 years ago, they did not know exactly how life impacted the Earth, if it did. But researchers were able to create a detailed timeline of how the Earth’s atmosphere changed during this time by analyzing the rings in ancient kauri trees.
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“Kauri trees are like the Rosetta Stone, and they help us unite records of environmental change in caves, ice cores and peatlands around the world”, Says co-professor Alan Cooper, an honorary researcher at the Museum of South Australia.
The researchers compared the newly created time scale with records of sites across the Pacific and used it in modeling the global climate, finding that the growth of ice sheets and glaciers in North America and the great changes to major wind belts and tropical storm systems can be traced to the Adams Event, named after researchers in honor of British science fiction writer Douglas Adams.
It was a time when seemingly random cosmic events and extreme environmental changes coincided. found worldwide 42,000 years ago.
One of its first clues was that the megafauna in mainland Australia and Tasmania went through simultaneous extinctions during this period.
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“This never seemed right, because it was a long time after the arrival of the aborigines, but it was almost at the same time that the Australian environment changed to the current arid state,” says Professor Cooper. The paper suggests that the event could explain many other evolutionary mysteries, such as the extinction of Neanderthals and the sudden and widespread emergence of figurative art in caves around the world.
Colombian physicist Santiago Andrés Triana, of the Royal Observatory of Belgium, comments that the reversal of magnetic poles is a phenomenon that has happened many times in the past and its precise causes are not fully understood.
“We know that the magnetic field is generated by a dynamo effect in the Earth’s liquid core. Currents in this ocean of liquid iron generate magnetic fields that in turn deliver more energy to these currents, in a feedback process that results in a large-scale magnetic field like the one we observe today. However, this process is not completely stable. The magnetic reversal of 42,000 years ago is evidence of this, “says Triana.
Triana adds that “during this relatively short period of inverted polarity, the magnetic field strength was much smaller than the normal intensity. This allows more radiation from electrically charged particles from the Sun to reach the surface of our planet, causing substantial damage to the ozone layer and, in turn, affecting the climate and the environment in general. “
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According to Triana, the magnetic field is currently weakening, although at a relatively slow pace: “We also know that there are periodic ‘strokes’ in the magnetic field, such as what is currently evidenced by the rapid drift of magnetic north pole from Canada to Siberia.
The magnetic inversion revealed by the Laschamps event, as it is called in the phenomenon described in the study, shows that surprising changes inside the Earth can occur on a very fast time scale (geologically speaking) and which can negatively affect the habitability of our planet. That is why it is important to study and understand as accurately as possible the processes that occur in the Earth’s core. Our future may depend on that, ”says Triana.
EUROPA PRESS