Earth Took Ten Million Years To Recover From Mass Extinction

Scientists from the University of Bristol and the China University of Geosciences have found that the earth took 10 million years to recover from mass extinction that took place 250 million years ago.

Life was nearly wiped out 250 million years ago at the end-Permian era, a crisis triggered by a number of physical environmental shocks such as global warming, acid rain, ocean acidification and ocean anoxia. These were enough to kill 90 per cent of living things on land and in the sea.

"It is hard to imagine how so much of life could have been killed, but there is no doubt from some of the fantastic rock sections in China and elsewhere round the world that this was the biggest crisis ever faced by life," said Dr Zhong-Qiang Chen, scientist at the China University of Geosciences, in a statement.

Scientists found that only 10 per cent of plants and animals survived. It is currently debated how life recovered from this cataclysm, whether quickly or slowly. Scientists found that the earth recovered quite slowly after the mass extinction.

The reason: the sheer intensity of the crisis, and continuing grim conditions on earth after the first wave of extinction.

The study revealed that grim conditions continued in bursts for some five to six million years after the initial crisis, with repeated carbon and oxygen crises, global warming and other ill effects.

Some groups of animals in the sea and on land did recover quickly and began to rebuild their ecosystems, but they suffered further setbacks. Life had not really recovered in these early phases because permanent ecosystems were not established.

"Life seemed to be getting back to normal when another crisis hit and set it back again. The carbon crises were repeated many times, and then finally conditions became normal again after five million years or so," said Professor Michael Benton, Professor of Vertebrate Palaeontology at the University of Bristol, in statement.

According to the scientists, after the environmental crises ceased to be so severe, more complex ecosystems emerged. In the sea, new groups, such as ancestral crabs and lobsters, as well as the first marine reptiles, came on the scene, and they formed the basis of future modern-style ecosystems.

"We often see mass extinctions as entirely negative but in this most devastating case, life did recover, after many millions of years, and new groups emerged. The event had re-set evolution. However, the causes of the killing - global warming, acid rain, ocean acidification - sound eerily familiar to us today. Perhaps we can learn something from these ancient events," Professor Benton added.