6th mass extinction

A research paper by Anthony Barnosky, a biology professor at the University of California at Berkeley, drew global attention when published in the journal Nature on March 2 amid doomsday rumors following Japan`s massive earthquake. His team compared the ratio of extinction between the number of mammal species that went extinct over the past 500 years, and that of mammal species secured from analysis of fossils. The ratio of extinction discovered in fossils was two species or fewer over a period of a million years. At least 80 mammal species were found to have gone extinct over the past 500 years, however. In light of this trend, Barnosky predicted that a mass extinction of mammals between 300 and 2,200 years from now.

Mass extinction is a phenomenon in which biological species go extinct in a very short period of time. Five mass extinctions occurred in the Ordovician, Devonian, Permian, Triassic and Cretaceous periods. The mass extinction of the Permian Period saw 96 percent of biological species including those in the sea go extinct some 250 million years ago and that of the Cretaceous Period caused the dinosaurs to disappear. Since humans now rule the planet, they could end up disappearing as well if the sixth mass extinction occurs.

The theory of the sixth mass extinction is not new. The U.N. Environment Program released a report in 2007 suggesting that the event is underway on Earth. If it materializes, chances are high that it will be caused by human destruction of the environment, including of habitats, global warming and the spread of deadly viruses. The causes of previous mass extinctions included change in eco-systems, including the depletion of oxygen in seawater, earthquakes and volcanic activities, and strike by comets or meteors. No single biological species has put all life on Earth in jeopardy, however. The gloomy prediction of scientists suggests signs of such a catastrophe happening in the not-so-distant future.

Alan Weisman, a science writer and journalism professor, wrote the book "The World Without Us" about what would happen if humanity suddenly vanished. He said he got the idea for his bestseller when visiting the Demilitarized Zone dividing the two Koreas. Isolated from humans for nearly 60 years since the end of the Korean War, the zone is now a haven for animals and a treasure trove for the eco-system. The message that a beautiful world could come after humans vanish is a scary warning for selfish human beings.

Editorial Writer Chung Sung-hee (shchung@donga.com)