Researchers analyzing minerals in fossilized ash from the most recent mega-eruption of Yellowstone National Park’s supervolcano say that it is due to blow up again much sooner than previously thought—and may wipe life off Earth in a matter of decades, National Geographic reports.

The Arizona State University researchers have found that the supervolcano could potentially send out more than 1,000 cubic kilometers of ash, which is 2,500 times more material than blew from Mount St. Helens in 1980, The New York Times reports. This could cover most of the United States and force the entire planet into a volcanic winter.

The supervolcano’s last giant eruption was over 630,000 years ago. This event created the 40-mile bowl that spans the Yellowstone park. This is not Earth’s only dormant supervolcano. Scientists guess that a supereruption occurs roughly every 100,000 years.

Geologists assumed that it would take hundreds of years for the next supervolcanic eruption—until now. The ASU researchers found in their analysis temperature changes and composition that have taken mere decades, instead of the expected centuries, and scientists are now realizing that the conditions that contribute to supereruptions could show within one lifetime.

These new findings further a 2011 study that found that the magma reservoir in Yellowstone had grown by 10 inches in seven years, which is very high, experts say. Major tourist attractions like the Old Faithful geyser and Grand Prismatic Spring are indications of that magma reservoir.