<P> The Siberian Traps had unusual features that made them even more dangerous . Pure flood basalts produce fluid, low - viscosity lava and do not hurl debris into the atmosphere . It appears, however, that 20% of the output of the Siberian Traps eruptions was pyroclastic (consisted of ash and other debris thrown high into the atmosphere), increasing the short - term cooling effect . The basalt lava erupted or intruded into carbonate rocks and into sediments that were in the process of forming large coal beds, both of which would have emitted large amounts of carbon dioxide, leading to stronger global warming after the dust and aerosols settled . </P> <P> In January 2011, a team, led by Stephen Grasby of the Geological Survey of Canada--Calgary, reported evidence that volcanism caused massive coal beds to ignite, possibly releasing more than 3 trillion tons of carbon . The team found ash deposits in deep rock layers near what is now Buchanan Lake . According to their article, "coal ash dispersed by the explosive Siberian Trap eruption would be expected to have an associated release of toxic elements in impacted water bodies where fly ash slurries developed...Mafic megascale eruptions are long - lived events that would allow significant build - up of global ash clouds ." In a statement, Grasby said, "In addition to these volcanoes causing fires through coal, the ash it spewed was highly toxic and was released in the land and water, potentially contributing to the worst extinction event in earth history ." In 2013, a team led by Q.Y. Yang reported the total amounts of important volatiles emitted from the Siberian Traps are 8.5 × 10 Tg CO, 4.4 × 10 Tg CO, 7.0 × 10 Tg H S and 6.8 × 10 Tg SO, the data support a popular notion that the end - Permian mass extinction on the Earth was caused by the emission of enormous amounts of volatiles from the Siberian Traps into the atmosphere . </P> <P> In 2015, evidence and a timeline indicated the extinction was caused by events in the Large igneous province of the Siberian Traps . </P> <P> Scientists have found worldwide evidence of a swift decrease of about 1% in the C / C isotope ratio in carbonate rocks from the end - Permian . This is the first, largest, and most rapid of a series of negative and positive excursions (decreases and increases in C / C ratio) that continues until the isotope ratio abruptly stabilised in the middle Triassic, followed soon afterwards by the recovery of calcifying life forms (organisms that use calcium carbonate to build hard parts such as shells). </P>

What was the cause of the permian extinction