Scientists Have Identified What Triggered The World’s Biggest Climate Catastrophe Some 252 million years ago the world was going through a tumultuous period of rapid global warming.
To understand what caused it, scientists have looked to one particular event in which a volcanic eruption in what is now Siberia spewed huge volumes of greenhouse gas into the atmosphere. Sea surface temperatures had increased by more than 6-8 ℃ in the hundreds of thousands of years leading up to the Siberian outpouring. Temperatures increased again after it, so much so that 85-95 percent of all living species eventually went extinct.
The eruption in Siberia obviously made a mark on the planet, but experts remained puzzled about what caused the initial warming before it. Our research reveals Australia’s own ancient volcanoes played a big role. Prior to the event in Siberia, catastrophic eruptions in northern New South Wales spewed volcanic ash across the east coast.
These eruptions were so large they initiated the world’s biggest ever climate catastrophe – the evidence for which is now hidden deep in Australia’s thick piles of sediment. Our study, published today in Nature, confirms eastern Australia was shaken by repeated “super eruptions” between 256 and 252 million years ago.
To put it into perspective, the 79 CE eruption of Mt Vesuvius, which obliterated the Italian city of Pompeii, produced just 3-4km³ of rock and ash. And the deadly Mt St Helens eruption in 1980 was about 1km³. The Australian eruptions would have repeatedly covered the entire east coast in ash – meters thick in some places. And a massive outpouring of greenhouse gases would have triggered global climate change.
Ancient sedimentary rocks provide us with a timeline of the environmental damage caused by the eruptions. Ironically, the evidence is preserved in coal measures. Today’s coal deposits in eastern Australia show ancient forests used to cover much of this land. After the super eruptions, however, these forests were abruptly terminated in a series of bushfires over some 500,000 years, 252.5–253 million years ago.
Without the forests, there was no plant matter to accumulate. The ecosystem collapsed and most animals Triggered became extinct. The subsequent eruptions in Siberia only exaggerated the devastation started by Australia’s supervolcanoes. And this collapse of ecosystems was not limited to Australia, either. The catastrophic event affected all of the ancient continents. It had a substantial influence on the evolution of life – which eventually led to the rise of the dinosaurs. Australia’s super eruptions were a key marker of change in the ancient world. As we look to achieving a more habitable climate in the future, who knew the clues to environmental catastrophe lay buried beneath our feet?
Acknowledgement: We would like to thank our colleague Phil Blevin from the Geological Survey of New South Wales for his contribution to this work.The Conversation Timothy Chapman, Postdoctoral Fellow in Geology, University of New England; Ian Metcalfe, Adjunct Professor, University of New England, and Luke Milan, , University of New England.
Source: This news is originally published by sciencealert