Devastating volcanic eruptions, caused by excess carbon in the atmosphere, could one day lead to the mass extinction of all marine animals, and possibly all life on Earth - so says a new study. The dire warning comes amid dramatic seismic events in Guatemala and Hawaii, where hundreds of people have been either killed or displaced from their homes in recent weeks. Researchers from Florida State University looked at data dating back millions of years to the Early Jurassic Period, when powerful volcanoes spewed huge amounts of carbon dioxide into the Earth's atmosphere, drawing oxygen from the world's oceans and killing marine life. The phenomenon was known as the 'Toarcian Oceanic Anoxic Event.' "It's extremely important to study these past events," said Theodore Them, a postdoctoral researcher at FSU. "It seems that no matter what event we observe in Earth's history, when we see carbon dioxide concentrations increasing rapidly, the result tends to be very similar: a major or mass