Supervolcano Rained Acid on Both Poles—But Wasn't So Bad After All?
Toba was Mount St. Helens times 5,000, but new evidence softens the fallout.
Roughly 74,000 years ago, Indonesia's Toba supervolcano pumped massive amounts of sun-shrouding ash and gases into the atmosphere, cooling the planet, possibly devastating early humanity, and—a new study reveals—raining sulfuric acid on both poles. (How Toba's eruption changed Earth.)
Scientists have long debated just how extensive and enduring those effects were. One study, for example, suggested the Toba blast spawned a thousand-year ice age that only some 10,000 individuals survived. Another has found evidence of humans thriving in relatively nearby India shortly after the eruption.
The new study—based on acid rain-tainted ice cores from Antarctica and Greenland—suggests Toba's fallout wasn't quite as catastrophic as might be expected.
The Antarctic ice core, for example, even bears traces of a warming