A new theory about the Great Mass Extinction

The extinction that occurred between the Permian and Triassic periods, 250 million years ago, in which about 90% of animal and plant species disappeared, was probably caused by the release of toxins into the air from dried up salt lakes

The largest mass extinction in Earth's history was caused by the release of halogen gases from salt lakes, which changed the atmospheric composition so drastically that vegetation was irreversibly damaged. This is what researchers hypothesize in an article published in the latest edition of the journal "Proceedings of the Russian Academy of Sciences". The extinction occurred between the Permian and Triassic periods, 250 million years ago, and about 90% of animal and plant species disappeared. Until now, it was thought that the extinction was caused by a volcanic eruption, the impact of an asteroid collision, the dehydration of methane.

The new theory is based on a comparison with biochemical changes and chemical processes in the atmosphere. "Our calculations show that pollutants emitted into the air from huge saline lakes, such as the Chestine Sea, probably caused disastrous consequences at that time," says Dr. Ludwig Wiebflug, from the Institute for Environmental Research of the Helmholtz Center. Observations predict an increase in the amount of desert areas and salt lakes as a result of climate change. This is why scientists predict that there will be an increase in the amount of halogen gases.

The team of researchers - which included scientists from Russia, Austria, South Africa and Germany - examined whether a process that began in an ancient period on Earth could have led to a global mass extinction, which reached its peak in the Permian period. The starting point for this theory was a discovery found in southern Russia and South Africa. A microbial process in salt lakes today has been found to produce and emit volatile halogenated carbons, such as chloroform, trichloroethane and tetrachloroethane. They discarded from the conclusions of the research on the Cheshtian Sea that existed 250 million years ago, in the Permian period, and was located in the area where Central Europe is today. The Chestine Sea, which spread over about 600,000 square kilometers, was almost the size of present-day France. This shallow Dead Sea was exposed at that time mainly to a dry desert climate and intense solar radiation. "We assume that the climatic, geochemical and microbial conditions in the Chestian Sea area are similar to those that exist today on the salty days we are investigating," Wiebflug says.

Based on the calculation of the amounts of halogen gas in the atmosphere, which are currently emitted by salty seas in southern Russia, the scientists estimated that from the Chisinau Sea alone, amounts of at least 1.3 million tons of trichloroethane, 1.3 million tons of tetrachloroethane, 1.1 million tons of chloroform and 0.05 million tons of methyl-chloroform were emitted annually. For comparison, the annual emission of trichloroethane and tetrachlorethane from industrial plants constitutes about 20% of the quantities specified, and only about 5% of the chloroform allegedly emitted from the Chestine Sea. Industrial emissions of methyl-chloroform, which damages the ozone layer, were outlawed in 1987 by the Montreal Agreement.

"By using prairie plant varieties, we were able to prove that halogen gases contribute to the acceleration of the desertification process: a combination of halogen carbons with dry climatic conditions leads to irreversible damage to the balance of the vegetation, and this accelerates the phenomenon of erosion," explains Dr. Carsten Kuta from the University of Heidelberg.

Based on these findings, the researchers propose the following hypothesis: at the end of the Permian era, the emission of halogen gases from the Cheshtian Sea and other salty seas was responsible for a complicated chain of events that led to the largest mass extinction in the history of the Earth, in which approximately 90% of animal and plant species became extinct.

"The question that remains unanswered is whether halogen gases from the giant salty seas were solely responsible for the extinction, or whether it was a combination of different components, including a volcanic eruption, an asteroid impact, or the dehydration of methane," says Ludwig Wiebflug. But the fact is that the effects of salty days have been underestimated. According to forecasts by the International Organization for Climate Change (IPCC), an increase in temperatures and dryness as a result of climate change will accelerate the desertification process in the future, thus increasing the areas of salty seas, salty lagoons and salt marshes. All this will lead to an increase in the formation of natural halogen gases. The toxic effect of these circumstances as well as pollutants present in the atmosphere will cause an increase in dryness and accelerate the natural toxins that cause climate change.

Participating in the preparation of the news: Nathaniel Mandelman

to the researchers' press release