Earth Equity News

Mass Extinctions Due to Sea Level Changes, Study Says. By John Roach, National Geographic, June 17, 2008. "The rise and fall of the seas may have a more lethal toll on Earth's life than asteroids and supervolacanoes, according to a new study. Over the past 540 million years, every increase in the rate of extinctions -- including the five so-called mass extinctions-has been linked to environmental changes wrought by changing sea levels, the study says. Only some mass-extinction events, though, have been clearly linked to space-rock impacts and supervolcano eruptions -- blasts many times greater than any in recorded times -- researchers say. 'To me, that is pretty striking,' study leader Shanan Peters, a geologist at the University of Wisconsin, Madison, said. The research may be especially relevant today, as what some scientists are calling the sixth mass extinction may already be underway, perhaps due to global warming... During the past 540 million years, there have been 5 major mass extinctions, primarily of marine plants and animals. Each time, between 75 and 95 percent of all species vanished. (See a prehistoric time line.) The idea that sea level changes are associated with these mass-extinction events has been around for almost 60 years, Peters noted, but until now scientists have been unable to quantify the environmental consequences of sea level change."