The temporary breakdown of the Earth’s magnetic field 42,000 years ago caused major climatic changes that led to global environmental transformations and mass extinctions.
As a new international study co-led by the University of New South Wales (UNSW), Sydney and the Museum of South Australia shows, this dramatic turning point in Earth’s history, mixed with thunderstorms, widespread auroras 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 make objects levitate driven by light).
“For the first time in history, we have been able to accurately date the timing and environmental impacts of the last magnetic pole reversal”says Chris Turney, a professor at UNSW and co-lead author of the study.
The finds were made possible by ancient New Zealand kauri trees, which have been preserved in sediments for more than 40,000 years. “Using the 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 the magnetic poles were temporarily reversed 41-42,000 years ago, They did not know exactly how life on Earth, if at all, impacted. But the researchers were able to create a detailed timescale of how 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, helping us to unite the records of environmental change in caves, ice cores and peatlands around the world.”says co-leading professor Alan Cooper, an honorary researcher at the Museum of South Australia.
The researchers compared the newly created timescale with records from 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 large changes in the major belts of Wind and tropical storm systems can be traced to the Adams Event, named by researchers after British science fiction writer Douglas Adams.
It was a time when seemingly random cosmic events and extreme environmental changes coincided found around the world 42,000 years ago.
One of his first clues was that the megafauna in mainland Australia and Tasmania went through simultaneous extinctions during that period.
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“This never seemed correct, because it was a long time after the arrival of the Aborigines, but it was around 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 appearance of figurative art in caves around the world.
The Colombian physicist Santiago Andrés Triana, from the Royal Observatory of Belgium, comments that The reversal of the magnetic poles is a phenomenon that has occurred 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 liquid core of the Earth. Currents in that 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 currently observe. 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 reversed polarity, the intensity of the magnetic field was much smaller than 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, albeit at a relatively slow rate: “We also know that ‘jerks’ occur periodically in the magnetic field, such as the one currently evidenced by the rapid drift of the magnetic north pole from Canada to Siberia.
The magnetic inversion revealed by the Laschamps event, as the phenomenon described in the study is called, shows that surprising changes in the Earth’s interior can occur on a very fast time scale (geologically speaking) and that they can negatively affect the habitability of our planet. That is why it is important to study and understand as precisely as possible the processes that occur in the Earth’s core. Our future may depend on it, ”says Triana.
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