UN says that Antarctic ozone layers are down by 30%

The World Meteorological Organisation (WMO) announced on 29 August that satellites above the continent recorded an average drop of 30% when compared to 1964-76 norms before ozone depletion was detected, which it described as “double the 15 percent reported two weeks ago and unusual for this early period”.

The WMO said that levels were unusual for this early period, as ozone depletion normally begins in late August and then intensifies until it peaks in October. However, the organisation stressed that it was too soon to say if there would be record depletion of the layer this year as meteorological conditions in the stratosphere could change, and much of the continent was still in darkness, limiting the area possible for ozone measurements by ground-based and satellite instruments which all require sunlight.

Preliminary ground-based measurements taken between August 16-22 from four Antarctic stations all showed substantial decreases when compared to the pre-ozone hole period, with France’s Dumont d’Urville reporting levels 20% below, Russia’s Mirny reporting 35% and Japan’s Syowa and Ukraine’s Vernadsky posting levels 25% below.

“Both Syowa and Vernadsky have ozone records extending back more than 25 years that indicate the Syowa weekly average is the second lowest on record while for Vernadsky this year is the lowest,” the WMO said.

“I don’t remember such a rapid increase in the proportion of ozone decrease,” a WMO spokesperson told edie, adding that scientists are awaiting sunnier conditions to take further measurements and then comment, “so as not to alarm people at this stage.”

Further measurements will be taken on 7 September, the spokesperson said, which will enable a clearer picture of the situation across more of the continent to emerge.

Ozone depletion is most acute over Antarctica because of its extremely cold winter conditions when ice clouds form in the upper atmosphere, allowing chemicals and sunlight to react with CFCs. This reaction releases chlorine which attacks ozone. At the same time a vortex forms and isolates Antarctic air, preventing other, relatively ozone-rich air from mixing and sustaining ozone levels. Due to the extreme cold, the vortex, which explains the timing and location of the ozone hole, remains intact until December.