A major reversal of the Earth’s magnetic poles, which occurred 42,000 years ago, may have caused a global climate catastrophe similar to those featured in Hollywood disaster film scripts. This is suggested by a study conducted by scientists from several countries, published in the journal Science last Friday (19).
According to the researchers, the extinction of Australia’s megafauna, the expansion of the ice sheet in North America, the disappearance of the last Neanderthals and the almost complete destruction of the ozone layer are some of the events related to the weakening of the Earth’s magnetic field recorded at the time.
Responsible for protecting the planet from cosmic radiation, the magnetic field weakened about 42,000 years ago, during the inversion of the poles, leaving the Earth without its defense against radiation from space. Such pole migration became known as the Laschamps Tour.
This event was already known by scientists, but the impacts caused by it were not known. With the new investigation, it was possible to gather evidence that the effects of the geomagnetic reversal were “apocalyptic”, according to the article, bringing consequences for the whole planet and of long duration.
How an ancient tree helped in the study
The investigation was based on the trunk of a kauri tree thousands of years old, taken from the bottom of a swamp in New Zealand, where it was preserved. With more than 2.5 meters in diameter, it has a time stamp on each of its rings, storing important information.
With the analysis of the rings, the scientists were able to create a detailed time scale about the changes in the Earth’s atmosphere in that period, following the increase in atmospheric radiocarbon levels, measuring and dating the impacts of the changes in the magnetic poles.
“As soon as we discovered the exact moment when kauri trees were registered, we could see that it perfectly matched the records of climatic and biological changes worldwide,” commented Alan Cooper, professor in the Department of Geology at the University of Otago, the study’s lead author.
Among the events reported by Cooper are the extinction of animals such as giant kangaroos and giant wombats in Australia, the disappearance of Neanderthals in Europe and a huge layer of ice advancing through the eastern USA. These and other situations would have been accelerated by the changes in ecosystems caused by the Laschamps Tour.