The Permian-Triassic mass extinction, also known as The Great Dying and “mother of all extinctions”, occurred 252 million years ago. It is Earth’s most devastating mass extinction event with up to 96% of all marine species and 70% of land animals becoming extinct. It is the only known extinction event to kill off insects. Strangely, it took life on Earth more than 5 million years to recover.
Now a joint study led by University of Leeds in the United Kingdom and China University of Geosciences in China have discovered that the cause of this lengthy event was a temperature rise to lethal levels. The researchers have determined that during the event, ocean temperatures rose above 100 degrees Fahrenheit (prior to this, climate modelers believed ocean temperatures could rise no higher than 86 degrees Fahrenheit) and land temperatures rose up to 140 degrees.
According to the study published in Science journal yesterday, the environment would have been very strange:
“The dead zone would have been a strange world – very wet in the tropics but with almost nothing growing. No forests grew, only shrubs and ferns. No fish or marine reptiles were to be found in the tropics, only shellfish, and virtually no land animals existed because their high metabolic rate made it impossible to deal with the extreme temperatures. Only the polar regions provided a refuge from the baking heat. This broken world scenario was caused by a breakdown in global carbon cycling. In normal circumstances, plants help regulate temperature by absorbing Co2 and burying it as dead plant matter. Without plants, levels of Co2 can rise unchecked, which causes temperatures to increase.”
To determine the temperatures during the Permian-Triassic extinction event, scientists studied 15,000 ancient conodonts, small teeth from extinct eel-like fishes.
According to Science journal:
“Conodonts form a skeleton using oxygen. The isotopes of oxygen in skeletons are temperature controlled, so by studying the ratio of oxygen isotopes in the conodonts he was able to detect temperature levels hundreds of millions of years ago.”
Professor Paul Wignall, co-author of the study noted:
“Hopefully future global warming won’t get anywhere near temperatures of 250 million years ago, but if it does we have shown that it may take millions of years to recover.”