Researchers believe that while humans are reversing ozone reduction, erupting supervolcanoes could drastically interrupt this recovery.
Last year it was revealed that humanity’s efforts to shrink the massive hole in the ozone layer were working. This ozone hole, first discovered above Antarctica in 1985, led nations to ban the use of chemical chlorofluorocarbons (CFCs) in 1987, with this action showing a 20pc reduction in the size of the hole decades later.
However, while this success could lead to an ozone layer of similar size to what it was in 1980 by 2050, scientists at the Chinese Academy of Sciences warn that cataclysmic natural events could seriously interrupt this.
In a paper published to Advances in Atmospheric Sciences, the researchers pinpointed the potential damage caused by supervolcanoes based on a transport and chemistry climate model jointly developed with Russian scientists. This simulated the impacts of supervolcano eruptions on the stratospheric ozone during different ozone recovery periods.
It showed that the total global mean column ozone depletion in a scenario with half the amount of harmful substances of the 1990s was at approximately 6pc, or 6.4pc in the tropics. When all ozone-depleting substances produced by humans are eliminated and only natural sources remain, a supervolcano would reduce the planet’s ozone layer by 2.5pc, or 4.4pc in the tropics.
The researchers’ concern is that since supervolcanic eruptions might inject large quantities of halogen into the atmosphere – which directly destroys ozone in the stratosphere – the true scale of depletion could be substantially higher than their estimates.
The big problem remaining for science is that current observations and studies can’t provide enough information on how much halogen enters the stratosphere. The researchers have also theorised that, based on these findings, supervolcanoes could have significantly influenced the evolution of life on our planet.
During the Palaeozoic era, supervolcanic eruptions occurring during a period when the ozone layer was relatively thin and weak could have destroyed it entirely. However, the researchers stressed that such questions require further investigation.