'Mega' El Niño may have fueled Earth's biggest mass extinction

The worst mass extinction in Earth's History may have been caused by a supercharged El Niño cycle.

New research suggests that an overload of carbon dioxide in the atmosphere led to the climatic shift, which, in turn, killed 90% of the species on Earth around 250 million years ago, at the end of the Permian period. The finding has implications for modern climate Science: Researchers don't know how current warming will affect the El Niño-La Niña cycle, but even a fraction of the disruption resulting from the world's worst mass extinction would make life for humanity very difficult.

"When we start pushing ourselves outside of those boundaries that we existed in for hundreds of thousands of years, it becomes uncharted territory," study co-author Alex Farnsworth, a paleoclimate modeler at the University of Bristol in the U.K., told Live Science.

Life flourished in the Permian period (298.9 million to 251.9 million years ago). The supercontinent Pangaea was ringed with lush forests where odd reptiles ranged alongside amphibians and whirring clouds of insects. In the oceans, towering reefs provided homes to spiral-shelled nautiluses, bony fish and sharks.

And then a set of giant volcanic rifts in what is now Siberia erupted. These rifts, known as the Siberian Traps, spewed massive amounts of carbon dioxide into the air. Worse, they erupted in an area rich in coal seams, which also vaporized into the atmosphere. The geological fallout from this eruption has been found in rock layers as far as South Africa.

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Exactly how the eruptions and the subsequent climate warming translated to mass death has been tricky to pin down. Other large eruptions did not lead to mass extinction, Farnsworth said. Plus, the timing of the deaths was odd: Terrestrial Animals started disappearing first, before the worst of the climate warming, and marine species followed.