Supervolcanoes have the power to cough up enough ash to coat entire continents. They emit waves of hot gas, rocks and ash that flow down their slopes at speeds so great they strip away vegetation and kill anyone in their path. And they carve vast depressions in the planet, leaving permanent scars.
And yet, they might not be as apocalyptic as previously thought. About 74,000 years ago, a supervolcano at the site of present-day Lake Toba on the Indonesian island of Sumatra rocked our world. But while it was the largest volcanic eruption of the last two million years, a new study published Monday in Nature suggests that humans not only survived the event — they thrived.
The study counters previous hypotheses, which suggested that the behemoth was so disastrous it caused the human species to teeter on the brink of extinction.
It’s easy to see how that idea came about. The Toba supereruption expelled roughly 10,000 times more rock and ash than the 1980 Mount St. Helens eruption. So much ejecta would have darkened skies worldwide, causing scientists to speculate that it might have plunged the Earth into a volcanic winter whose chill could be felt far from Indonesia. Climate models suggest that temperatures may have plummeted by as much as 30 degrees Fahrenheit. And in such a cold world, plants may have ceased growing, glaciers may have advanced, sea-levels may have dropped and rainfall may have slowed.
Then in 1998, Stanley Ambrose, an anthropologist, linked the proposed disaster to genetic evidence that suggested a population bottleneck had occurred around the same time. He was certain that the Toba supereruption had caused the human population to decline to some 10,000 people — a close call for our ancestors.