Agencies report ozone-hole peak smallest recorded since 1982

The Antarctic ozone hole hit its smallest annual peak on record since tracking began in 1982, the National Oceanic and Atmospheric Administration and NASA announced Monday.

But, while there’s been progress in cutting down on the use of ozone-depleting chemicals, the agencies cautioned that the milestone doesn’t mean the problem has been solved. Instead, scientists attribute the relatively tiny ozone hole to unusually mild temperatures in that layer of the atmosphere.

According to NASA and the NOAA, the annual ozone hole — which consists of an area of heavily depleted ozone high in the stratosphere above Antarctica, between 7 and 25 miles above the surface — reached its peak extent of 6.3 million square miles on Sept. 8 and then shrank to less than 3.9 million square miles during the rest of September and October.

“During years with normal weather conditions, the ozone hole typically grows to a maximum of about 8 million square miles,” the agencies said in a news release.

This is the third time in 40 years that weather systems have caused warm stratospheric temperatures that put the brakes on ozone loss, the federal science agencies said. Similar weather patterns led to unusually small ozone holes in 1988 and 2002, they reported.

“It’s a rare event that we’re still trying to understand,” Susan Strahan, an atmospheric scientist at the NASA’s Goddard Space Flight Center in Maryland, said in the release. “If the warming hadn’t happened, we’d likely be looking at a much more typical ozone hole.”

The stratospheric ozone layer helps deflect incoming ultraviolet radiation from the sun, shielding life on Earth from its harmful effects, such as skin cancer, cataracts and damage to plants. However, chemicals used for refrigeration purposes, such as chlorofluorocarbons [CFCs] and hydrofluorocarbons [HFCs], break down stratospheric ozone molecules, thereby exposing the planet’s surface to greater amounts of UV radiation.

The Montreal Protocol, a landmark international environmental treaty that took effect in 1988, has reduced CFC emissions worldwide.