Throughout earth’s history, several forms of mass extinctions almost caused the elimination of all life on earth. Moreover, though data prove the incidents, scientists were never truly able to pinpoint the reason behind them. From asteroid impacts to cosmic ray blasts, many theories rose to justify the frightening occurrences. However, a new study suggests that the earth itself may have a leading role in these catastrophes. Recently, research published in Earth and Planetary Science Letters accuses the Earth’s magnetic field as a culprit. Thus, it explains how the reversals of the Earth’s magnetic field may have sparked mass extinctions in the past by stripping oxygen from the atmosphere.
The natural state of the magnetic field
Almost every 500,000 years, the earth’s magnetic field, which is conjured in the liquid outer core, spontaneously changes direction. Scientists call this change the geomagnetic reversals. During this process, the north and south poles fields swap places.
Now, under normal circumstances, the magnetic field acts as a shield around the atmosphere. It protects our world from the damaging effects of the sun and the solar wind. However, during geomagnetic reversals, the atmosphere becomes extremely vulnerable to the full force of the solar wind since the field is weakened greatly. Furthermore, in the field’s weakened state, oxygen ions end up being stripped off into space.
Though terrifying, scientists regard this as a well known old fact. However, Yong Wei of the Chinese Academy of Sciences and his team are now tying this occurrence with mass extinctions. In his recent study, he and his team are aiming to discover whether the oxygen lost during geomagnetic reversals could bring about mass extinctions.
For a long time, scientists believed that mass extinctions are often accompanied by both an increase in the rate of geomagnetic reversals and a decrease in atmospheric oxygen levels. Therefore, in the study, they aim to decide whether geomagnetic reversals are capable of causing such oxygen loss. Hence, whether geomagnetic reversals can lead to mass extinction.
The levels of Oxygen Depletion
Wei and his team choose to focus on the “Triassic-Jurassic” mass extinction that took place almost 200m years ago. During that extinction, almost 84% of all species on Earth perished from existence. Moreover, other Independent studies had proved that the geomagnetic reversal rate doubled during that time while the amount of atmospheric oxygen simultaneously dropped by 9 percent.
Furthermore, with the aid of a computer model, they were able to conduct a stimulation proving that the geomagnetic reversals stripped at least 218 trillion tons of oxygen from the Earth’s atmosphere during the Triassic-Jurassic extinction. Thus, the reversals alone were the reason behind at least half of the 9 percent oxygen drop that occurred during the extinction. Therefore, the effect of the geomagnetic reversals is enough to play a major role in the die-off according to the study’s author.
Explaining the unknown
This theory can also end up explaining even deadlier and scarier mass extinctions. Study coauthor Markus Fraenz, of the Max Planck Institute for Solar System Research, states that “the oxygen loss caused by geomagnetic reversals could also have caused the end-Permian mass extinction, in which up to 97% of all species were wiped out”.
In brief, theories behind the reasons for mass extinctions vary and now we have yet another theory for them. Geomagnetic reversals may not be the flashier way to end the world, but it’s a really terrifying possibility nonetheless.
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