The Antarctic Ozone Hole This Year Could Be The Smallest Since 1988

Scientists at the EU's Copernicus Atmosphere Monitoring Service who track the size of the ozone hole in the Antarctic report that it is expected to be atypically small this year.

BBC News reported that the annual hole that opens up in the Antarctic sky during the southern hemisphere spring is under half of the size that it typically reaches in September.

In addition, the hole is farther from the pole than it's normally found at this time of year. CAMS predicts that ozone depletion will occur at normal rates from this point, resulting in a significantly smaller gap in the ozone layer than has been seen since 1988.

Scientists have been monitoring the hole in the Antarctic ozone since it was announced in a 1985 paper by Joe Farman, Brian Gardiner and Jonathan Shanklin published in Nature.

By 1987, the Montreal Protocol was signed by 46 nations to commit to reducing the chemicals that cause ozone degradation.

CAMS deputy head Richard Engelen does not have an explanation for the smaller hole seen this year.

"It's not really related to the Montreal Protocol where we've tried to reduce chlorine and bromine in the atmosphere because they're still there," he told the BBC. "It's much more related to a dynamical event. People will obviously ask questions related to climate change, but we simply can't answer that at this point."

Model of ozone hole over Antarctic
Model of the ozone hole over the Antarctic in September of 2019 Copernicus Atmospheric Monitoring Service

Ozone is a naturally-occurring chemical consisting of a trio of oxygen atoms. When ultraviolet rays from the sun interact with ordinary oxygen molecules (made up from two atoms) in the upper atmosphere, the molecules are split in two. Each of those free oxygen atoms then bonds to another molecule to form ozone. This process is constantly repeated, diffusing a significant amount of UV radiation as heat before it reaches the Earth's surface.

In a stable environment, this cycle balances itself out. But human production of chemical compounds such as chlorofluorocarbons has reduced the ozone cycle's efficiency. These chlorine-containing molecules break down in the atmosphere as well, but their chlorine atom can break apart ozone to form ordinary oxygen chlorine monoxide, according to NASA. That reduces the efficiency of the ozone layer's UV filtering power.

Each year, the Coriolis effect caused by the Earth's rotation brings a westerly air current over the pole that causes the production of "polar stratospheric clouds." These clouds provide a surface for ozone-destroying chemical reactions to occur, resulting in ozone depletion over the same geographical area each year.

Reducing human production of chlorofluorocarbons has been a major goal of the environmental movement since their effect on the ozone layer was discovered. In 2018, the World Meteorological Association released a report saying that human efforts to return ozone to pre-1970 amounts could happen by 2060.