Are humans causing a mass extinction on the magnitude of the one that killed the dinosaurs?The answer is yes, according to a new analysis - but we still have some time to stop it.

Mass extinctions include events in which 75 percent of the species on Earth disappear within a geologically short time period, usually on the order of a few hundred thousand to a couple million years. It's happened only five times before in the past 540 million years of multicellular life on Earth. (The last great extinction occurred 65 million years ago, when the dinosaurs were wiped out.) At current rates of extinction, the study found, Earth will enter its sixth mass extinction within the next 300 to 2,000 years.

"It's bittersweet, because we're showing that we have this crisis," study co-author Elizabeth Ferrer, a graduate student in biology at the University of California, Berkeley, told LiveScience. "But we still have time to fix this."

Others aren't so optimistic that humans will actually do anything to stop the looming disaster, saying that politics is successfully working against saving species and the planet. [ YAHOO NEWS ]