Is the Hole in Ozone Layer Closing? First Signs of Healing

The infamous "hole in the ozone layer" may be en route to recovery. MIT News reported that a team led by MIT climatologist Susan Solomon said that they have detected "the first fingerprints of healing" in the depleted ozone region over Antarctica.

In a paper submitted to the journal Science, Solomon's team shared their discovery that the September ozone hole has gotten smaller by over 1.5 million square miles (about 3.88 million sq. km) since the peak of depletion in 2000. The scientists expected the ozone replenishment to continue, and predicted that the ozone hole will have recovered permanently by mid-century, unless future volcanic eruptions come to disrupt the healing process.

Climate scientists have typically used the October measurement of the total ozone value as the benchmark in their studies. While ozone loss was first detected in the 1950s, the noteworthy finding came in the '80s when a landmark British Antarctic survey released results which showed that the October total ozone value was decreasing.

October is the time of the year when the ozone hole reachest its fullest extent. Solomon's team decided against using the October benchmark because measurements taken during that month could be significantly influenced by various meteorological conditions.

"September is a better time to look because chlorine chemistry is firmly in control of the rate at which the hole forms at that time of year," Solomon informed MIT News.

Chlorine originating from chlorofluorocarbons (CFCs) triggers chemical reactions that lead to the destruction of the ozone layer. The Montreal Protocol, signed by most of the world's nations in 1987, sought to curb human production of CFCs in a global effort to restore the ozone layer.

Solomon's team engineered a simulation that could issue predictions of total ozone value based on yearly estimates of the amount of chlorine in the atmosphere, EarthSky.org reported. The team, finding that the hole in the ozone had shrunk compared to its size in 2000, also saw that this drop matched the simulation's prediction. This gave them the confidence to support its prediction of the eventual restoration of the ozone layer.