merbs writes: The biggest extinction event in planetary history was driven by the rapid acidification of our oceans, a new study concludes (abstract). So much carbon was released into the atmosphere, and the oceans absorbed so much of it so quickly, that marine life simply died off, from the bottom of the food chain up. That doesn't bode well for the present, given the similarly disturbing rate that our seas are acidifying right now. A team led by University of Edinburgh researchers collected rocks in the United Arab Emirates that were on the seafloor hundreds of millions of years ago, and used the boron isotopes found within to model the changing levels of acidification in our prehistoric oceans. They now believe that a series of gigantic volcanic eruptions in the Siberian Trap spewed a great fountain of carbon into the atmosphere over a period of tens of thousands of years. This was the first phase of the extinction event, in which terrestrial life began to die out.