By intern reporter Kang Xin

(Caijing.com.cn) Volcanic activity has most likely contributed to the largest mass extinction in the Earth's history, according to a paper by British and Chinese scientists published in Science on May 29. 

Massive eruptions in Mount Emei unleashed around a half million cubic kilometers of lava about 260 million years ago, covering an area five times the size of Wales. This environmental catastrophe caused the extinction of 90 percent of the world's marine life and 70 percent of land species, according to the paper.

Previous studies pointed to volcanoes as likely causes for large mass extinctions but the evidence was elusive.

Finding a direct cause-effect link between volcanic activity and mass extinctions is difficult because the fossils that mark the extinctions are rare in volcanic regions. Researchers finally made a breakthrough in Mount Emei in southwest China, which, in the past, was located below sea level. Volcanic rock sandwiched between layers of limestone contains easily datable marine fossils, which provides the most precise and direct evidence for the link between the volcanic explosion and mass extinction.

While volcanic eruption can lead to the emission of large amounts of greenhouse gases, some scientists have argued that global warming is a long process and it could not have caused a large mass extinction. The report has provided an explanation.

Lava at extremely high temperatures projected into the sea during the volcanic eruption, causing a sharp cooling that produced clouds of volcanic dust and sulfide. The clouds reflected and absorbed sunlight, which caused a global cooling effect that limited the growth of photosynthetic creatures. Long periods of acid rain spelled disaster for world species, especially marine life, according to the paper.

Full article in Chinese: http://www.caijing.com.cn/2009-06-02/110174840.html