Researchers have identified a slump magnetic field reversal In the case of Earth, about 40 million years ago, big questions arose about how long these reversals actually take and how we would be affected by the next one.
As far as geological time scales are concerned, magnetic field reversals are thought to occur fairly regularly. There have been about 540 reversals in the past 170 million years, and they seem to have happened for billions of years.
But 40 million years ago, something was different. According to an international team of researchers, one transition from this period took 18,000 years and the other at least 70,000 years, much longer than the typical period of about 10,000 years that scientists consider standard.
“This discovery truly surprised us, revealing an unusually long-lasting reversal process and challenging conventional understanding.” I will write Lead author Yuji Yamamoto (Kochi University), a paleomagnetologist.
“The variation in reversal durations revealed in this study reflects the unique dynamical properties of Earth’s geomagnetic field and provides empirical evidence that geomagnetic reversals can last significantly longer than the widely assumed 10,000-year period.”
The research team analyzed sediment cores extracted from a location off the coast of Newfoundland in the North Atlantic Ocean. The magnetic signals within these cores are locked into tiny crystals that reveal their orientation. earth’s magnetic field over a vast period of time.
In this case, the researchers took a closer look at a particular layer, which is 8 meters (just over 26 feet) from top to bottom. Eocene. There was a clear change in polarity, but it was over an unexpectedly wide range of sediment cores.
Two magnetic field reversals were discovered, one lasting about 18,000 years and the other 70,000 years. Computer modeling suggested that such an event could span 130,000 years in some cases, but it was not seen in the geological record.
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These magnetic field reversals are caused by changes in Earth’s liquid iron and nickel outer corearound it 2,200km (1,367 miles) thick. This outer core is always in magnetic flux, but it can become unstable enough to change the position of the magnetic poles.
The planet does not flip over, but magnetic north becomes magnetic south and vice versa. After tens of thousands of years, the compass will eventually point in the opposite direction. incredibly confusing.
These newly identified flips not only took longer, but were also messier and more variable than the researchers expected. There have been multiple “rebounds” where the magnetic field appears unsure in which direction it will go, consistent with the results of our planet’s latest reversal – Brunges vs. Matsuyama comeback.
“The occurrence of multiple rebounds is not unheard of. This behavior has also been reported in Brunges and Matsuyama reversals.” write The researchers state in their published paper:
“We suggest that it may be more common and that polarity reversals are inherently complex events, if not somewhat chaotic.”
The Brunges-Matsuyama reversal, which occurred about 775,000 years ago, supports the new discovery. a Study from 2019 It turns out that the inversion took 22,000 years to complete. Therefore, long-term reversals may be the rule rather than the exception.
Next time it happens, we must be prepared. One of the consequences of the magnetic field reversal is that our planet much less protection From radiation falling from space and geomagnetic activity.
If that exposure lasts tens of thousands of years longer than previously thought, we need to know about it. It has the potential to disrupt everything from animal species to the climate system, but that requires more research. Know the exact effect.
Related: Signs of a mysterious structure near the core detected in the Earth’s magnetic field
“This is basically saying that we are exposing the entire planet, not just particularly high-latitude regions, to this cosmic radiation at higher rates and over longer periods of time.” say Peter Lippert, a paleomagnetist at the University of Utah.
“Therefore, it is logical to expect a higher incidence of genetic mutations. Atmospheric erosion may occur.”
This study Communication Earth and Environment.