Unlike the marine environment, the mechanisms that led to the mass extinction that took place on earth’s continents at the end of the Permian are still poorly understood. A new study shows that the terrestrial environment, in particular, was devastated by sulfuric acid rain and major climate change.
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 over 70% of terrestrial species became extinct.
The causes of this extinction are mainly attributed to intense volcanic activity in the Siberian Traps and possibly other recently identified volcanoes, which altered the chemistry of the oceans and caused catastrophic global warming, resulting in toxic environmental conditions for most marine life. However, little is known about the mechanisms that led to the extinction of terrestrial species.
Sulfate aerosols in the atmosphere at the end of the Permian
In a new study, a team of Chinese and American scientists has therefore sought to uncover the physical and chemical causes and mechanisms behind the extinction of a wide range of terrestrial species. After sampling and analyzing more than 1,000 meters of sediment cores to reconstruct Permian environmental conditions, the researchers found that this period was associated with major climatic disturbances caused by the presence of sulfate 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 climate warming.
Acid rain, volcanic winters, and warming: A perfect combination for mass extinction
The study, carried out in Australia’s Sydney Basin, shows that the extinction of continental species coincides with a clear change in atmospheric composition. Measurements show a significant increase in atmospheric sulfate concentration, which is linked to the dispersal of large amounts of sulfate aerosols from the ongoing Trapps eruption in Siberia. The presence of these aerosols would have led to sulfuric acid showers 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 decreases are linked to the ability of aerosols to reflect sunlight and prevent solar energy from reaching the Earth.
Sulfate aerosols are also responsible for other phenomena, this time leading to temperature increases: depletion of the ozone layer and warming of the middle layers of the atmosphere by absorption of infrared radiation.
Extinction on land is thought to have started 200,000 to 600-000 years before extinction in the oceans
The destruction of the ecosystems by sulfuric acid rain and the climate disruptions are thought to have combined to cause severe global degradation of the terrestrial environment, leading to the extinction of many species living on 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.