By Patrick Cullis, CIRES and NOAA scientist  The 2021 Antarctic ozone hole is taking shape as we move into the ozone depletion season. Stratospheric temperatures are frigid and the Sun is activating chlorine, beginning a catalytic reaction in which a single chlorine molecule will destroy thousands of ozone molecules, while South Pole ozonesonde measurements show… Read More


By Irina Petropavlovskikh, Secretary of the International Ozone Commission and a CIRES and NOAA scientist  September 16 is the International Day for the Preservation of the Ozone Layer, celebrating the 1987 anniversary of the Montreal Protocol on Substances that Deplete the Ozone Layer. The Montreal Protocol is the globally ratified treaty that controls the production… Read More