Thunderstorms are punching new holes in the ozone layer over the US, say Harvard University scientists.
The ozone loss, they say, is both serious and entirely unexpected, as it's been observed a long way from the polar regions to which it was originally thought to be restricted.
A team led by professor James G Anderson has discovered that during intense summer storms over the United States, convection carries water vapor far higher into the lower stratosphere than previously thought possible, leading to substantial, widespread ozone loss throughout the following week.
"What proved surprising was the remarkable altitude to which water vapor was being lofted — altitudes exceeding 60,000 feet — and how frequently it was happening," says Anderson.
Where the water vapor was injected into the stratosphere, the researchers found that the catalytic loss of ozone increased a hundredfold - meaning, says the team, that ozone could be being lost far faster than it can be replaced.
And while the data comes from the US only, the team says the same thing could be happening elsewhere.
There are, clearly, public health implications to the study, thanks to the increased risk of skin cancer. And, says the team, if the stratosphere becomes wetter, as has happened in the past when CO2 levels have risen, things could really get serious.
"Were the intensity and frequency of convective events to increase irreversibly as a result of climate forcing, decreases in ozone and associated increases in UV dosage would also be irreversible," says the team.