New research suggests ocean acidification and volcanic activity caused the most dramatic mass extinction in history.
The devastating extinction took place 252 million years ago, and killed off 90 percent of marine speices and over two-thirds of the animals present on land, the University of Edinburgh reported. The event occurred when the Earth's oceans absorbed giant amounts of carbon dioxide emitted by volcanic eruptions. The massive absorption changed the ocean's chemistry, causing it to become more acidic. This acidification was believed to be what pushed extinction event over the edge, causing the massive loss of diversity.
The findings could help researchers gain insight into the threat imposed by ocean acidification on modern sea life. The amount of carbon released in the atmosphere during the historical extinction was believed to have been larger than what exists in fossil fuel reserves today, but it was released at a rate similar to modern emissions.The Permian-Triassic Boundary extinction took place over a period of 60,000 years, and persisted for another 10,000.
"Scientists have long suspected that an ocean acidification event occurred during the greatest mass extinction of all time, but direct evidence has been lacking until now. This is a worrying finding, considering that we can already see an increase in ocean acidity today that is the result of human carbon emissions," said Matthew Clarkson, of the University of Edinburgh's School of GeoSciences, who co-ordinated the study.
To make their findings the researchers looked at rocks under the United Arab Emirates, which was the ocean floor at the time of the mass extinction. This allowed them to create a climate model for what drove the event.
"This work was highly collaborative and the results were only possible because we assembled a unique team of geochemists, geologists and [modelers] to tackle an important and long-standing problem," said professor Rachel Wood, of the University of Edinburgh's School of GeoSciences.
The findings were published in a recent edition of the journal Science.
