Record Loss In Arctic’s Ozone Layer

Some 14 years after the Montreal protocol led to a phasing out of ozone-depleting chemicals in refrigerators, fire extinguishers, and aerosol spray cans, lingering chlorofluorocarbons in the stratosphere and a particularly cold winter have combined to decrease the Arctic’s ozone layer by a record 40%, according to scientists at the World Meteorological Organization. Previously, the highest ozone layer loss recorded over the Arctic was 30% during winter months. Speaking on April 5 at the European Geosciences Union’s annual meeting in Vienna, WMO’s Geir O. Braathen said that the decrease in the Arctic’s ozone layer “is not because the Montreal protocol doesn’t work.” Without the Montreal protocol, this year’s Arctic ozone loss probably would have been worse, Braathen noted. Instead, Arctic stratosphere temperatures dropped this winter below –78 °C, which led to cloud formation. In these clouds, chlorofluorocarbons emitted before the ban can cause ozone-depleting chemical reactions. Unlike the Antarctic, which has an annual ozone layer loss due to consistently low winter temperatures, the Arctic’s ozone layer is sometimes not reduced at all during the winter months when temperatures in the stratosphere don’t drop too low. Because of the long lifetimes of ozone-depleting chemicals in the stratosphere, the Arctic’s ozone layer is not expected to return to pre-1980 levels until at least 2030.