Arctic Ozone Thins

Unusually chilly temperatures in part of the Arctic atmosphere and iridescent ice clouds there are triggering significant depletion of the protective ozone layer, according to recent, ongoing observations by NOAA scientists and international colleagues.

“This is pretty sudden and unusual,” said Bryan Johnson, a research chemist in the Global Monitoring Division of NOAA’s Earth System Laboratory (ESRL) in Boulder, Colo., and leader of ESRL’s Ozonesonde Group.

The stratospheric ozone layer protects Earth from damaging ultraviolet radiation, but chlorine and bromine from air pollutants such as chlorofluorocarbons and similar compounds can eat away at ozone in the right conditions: Temperatures below -78C (cold enough to form nitric acid-containing ice crystals in the relatively dry atmosphere) and sunlight (to trigger chemical reactions on ice surfaces).