A microbial feeding frenzy may have fueled the biggest mass extinction in Earths history, new research suggests. The findings suggest that bacteria, with a little help from massive volcanism, produced large quantities of methane, thereby killing 90 percent of life on the planet. About 252 million years ago, more than 96 percent of ocean life and 70 percent of land-based life forms died in an event known as the end-Permian extinction. The mass die-off happened in a geologic flash of just 60,000 years. Scientists have proposed everything from massive meteor impacts to coal explosions to rifting supercontinents to explain this cataclysmic extinction. [Wipe Out: Historys Most Mysterious Extinctions] Rocks from that time period in locations such as Meishan, China, show that atmospheric carbon-dioxidelevels skyrocketed right around the time of the extinction. Sediments also show that during this time, the largest set of volcanic eruptions in recorded geologic history — called the Siberian Traps — spewed enough lava to cover the entire landmass of the United States, said study co-author Gregory Fournier, a biologist at the Massachusetts Institute of Technology. Therefore, many researchers have theorized that the Siberian Traps could have belched out the extra carbon dioxide, choking life on the planet.
Posted on: Mon, 31 Mar 2014 20:43:34 +0000