Would modern humans survive a volcanic winter

Some 74,000 years ago an Indonesian super-volcano exploded, blanketing the planet in a thick cloud of ash, and plunging our ancestors into a decade long volcanic winter, followed by centuries of cool climate. Or did it? The impact of this mega-eruption is heavily debated by scientists, but new ice core evidence suggests that Toba didn't chill the world quite as much as we thought.

Toba's ash has never been found in polar ice cores, but now Anders Svensson, from the University of Copenhagen in Denmark, and his colleagues, found traces of Toba in Greenland and Antarctica, by measuring acidity levels in the ice. In both ice cores the scientists found four acidic spikes within a few hundred years, caused by volcano-induced acid rain. Possibly this means that Toba erupted four times in quick succession, or that another very large tropical volcano was erupting around the same time.

Regardless of the number of eruptions, the width of the acid rain spikes show that the climate bounced back to normal after just a few years each time. "A long-term global winter seems out of the question," says Svensson. This lesser catastrophe fits with archaeological evidence from India, which shows that our ancestors survived the mega-eruption, despite being blanketed by ash. Without doubt there will be another super-volcanic eruption one day. That Toba was not as devastating as previously thought is somewhat reassuring, though whether we'd be as resilient as our ancestors remains to be seen.