Unlike the marine environment, the mechanisms that led to the mass extinction that took place on the terrestrial continents at the end of the Permian are still poorly understood. A new study shows that the Earth’s environment, in particular, has been devastated by sulfuric acid rains and major climate change.
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Acid rain
The end of the Permian, some 252 million years ago, represents a critical period in the history of life on Earth. It was the greatest biological crisis in the history of life on earth when almost 90% of marine species and more than 70% of terrestrial species disappeared.
The causes of this extinction are mainly attributed to intense volcanic activity in the Siberian Traps and possibly other recently identified volcanoes, which have altered ocean chemistry and caused catastrophic global warming, resulting in mostly toxic environmental conditions. of marine life. However, little is known about the mechanisms that led to the extinction of terrestrial species.
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Sulfate aerosols in the atmosphere at the end of the Permian
In a new study, a team of Chinese and American scientists therefore sought to uncover the physical and chemical causes and mechanisms behind the extinction of a wide range of terrestrial species. After collecting and analyzing more than 1,000 meters of sediment cores to reconstruct the environmental conditions of the Permian, the researchers found that this period was associated with major climatic disturbances caused by the presence of sulphate aerosols in the atmosphere. Short periods of cooling, similar to volcanic winters, would have occurred as part of a long-term global pattern of extreme global warming.
Acid rain, volcanic winters and warming: a perfect combination for a mass extinction
The study, conducted in the Sydney Basin in Australia, shows that the extinction of continental species coincides with a marked change in atmospheric composition. Measurements show a significant increase in atmospheric sulfate concentration, which is related to the dispersal of large amounts of sulfate aerosols from the ongoing Trapps eruption in Siberia. The presence of these aerosols would have resulted in showers of sulfuric acid in parallel with significant climatic variations. It is well known that volcanic sulfur aerosols cause short volcanic winters that precede longer periods of global warming. These short-term temperature drops are related to the ability of aerosols to reflect sunlight and block solar energy from reaching Earth.
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Sulphate aerosols are also responsible for other phenomena, this time leading to temperature rises: depletion of the ozone layer and warming of the middle layers of the atmosphere by absorption of infrared radiation.
The extinction on land is thought to have started 200,000 to 600,000 years before the extinction in the oceans
The destruction of ecosystems by sulfuric acid rains and climatic disturbances would have combined to cause serious global degradation of the terrestrial environment, leading to the extinction of many species living on the continents.
This extinction of terrestrial species would have preceded the extinction of marine species by 200,000 to 600,000 years. The results of this study were published in the journal Earth and Planetary Science Letters.
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References
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