Ozone Layer depletion
Ozone Layer depletionwikimedia commons

The hole in the ozone layer above Antarctica is healing. Scientists at MIT have observed that the hole in the ozone layer has shrunk by over four million square miles since the year 2000 when ozone depletion was at its peak.

The scientists detailed their observations in the journal, Science. They say that while the rate of healing was hindered by the eruption of volcanos, the ozone layer was on a definite path towards healing.

The hole in the ozone layer was created largely due to chlorofluorocarbons (CFCs), which are emitted by old refrigerators, aerosol sprays like hairsprays and dry cleaning processes. Almost the entire world came together to sign the Montreal Protocol in 1987 and actively banned the use of CFC. It appears that the efforts have finally paid off.

"We can now be confident that the things we've done have put the planet on a path to heal," says lead author Susan Solomon, the Ellen Swallow Richards Professor of Atmospheric Chemistry and Climate Science at MIT, in a statement. "Which is pretty good for us, isn't it? Aren't we amazing humans, that we did something that created a situation that we decided collectively, as a world, 'Let's get rid of these molecules'? We got rid of them, and now we're seeing the planet respond."

The researchers tracked the yearly opening of the Antarctic ozone hole between 2000 and 2015 every September. They also analyzed ozone measurements taken from weather balloons and satellites, analysed satellite measurements of sulfur dioxide, typically from volcanos that also influence the ozone layer.

While Chlorine is the ozone layer's biggest enemy, temperature and sunlight also play a role in accelerating the depletion of the ozone layer. For chlorine to deplete the ozone layer, the weather needs to be cold enough to to create polar stratospheric clouds. While volcanos don't release much chlorine into the atmosphere, they do help form polar stratospheric clouds.

Solomon expects to see the hole in the ozone layer close by midcentury and the only thing that could possibly throw this trend off track is a series of massive volcanic eruptions.