When a typhoon saved Earth from an ozone-destroying volcanic eruption

In June 1991 Mount Pinatubo blew its top in spectacular fashion, producing one of the greatest volcanic eruptions in the 20th Century.

The eruption killed  800 people and left 10,000 homeless, and ejected so much dust into the atmosphere that it had a major effect on climate, depressing global temperatures by around 0.5°C for a couple of years.

But if Typhoon Yunya hadn’t coincided with the eruption, the impact could have been significantly worse.

Along with magma and ash, vast quantities of hydrogen chloride pumped out of Pinatubo. Had this hydrogen chloride reached the stratosphere it would have initiated chemical reactions with chlorine (which is increased thanks to all chlorofluorocarbons – CFCs – we have pumped out) and massively thinned Earth’s ozone layer.

But Typhoon Yunya powered its way through the eruption plume and washed most of the hydrogen chloride out before it got anywhere near the stratosphere.

But new research suggests that future Pinatubo-esque eruptions would likely cause serious thinning of the ozone layer, having a significant impact on skin cancer rates, livestock mortality and crop yields.

“The implications for surface life on Earth from such a future eruption could be profound,” the scientists write in Geophysical Research Letters. The study showed that short-lived bromine (produced by marine plankton and micro-algae) will still facilitate this dramatic ozone thinning reaction in the stratosphere for decades to come.

Source: When two disasters saved Earth from a worse one | Science | The Guardian