World Meteorological Organization (WMO) said colder-than-usual high
altitude temperatures over the Antarctic combined with ozone-eating
gases lingering in the atmosphere had stretched the ozone hole to an
average of 26.9 million square kilometres over a 30 day period -
covering an area larger than all of North America.
is the third largest observed after the record-breaking ozone holes
in 2000 and 2006," the UN's climate and weather agency said in a
hole peaked on 2 October, when it measured 28.2 million sq km,
according to the measurements conducted by the US space agency NASA.
shows that the ozone hole problem is still with us and we need to
remain vigilant," WMO scientist Geir Braathen said in the
there is no reason for undue alarm."
size of the hole in the ozone layer above the Antarctic fluctuates,
usually peaking during the polar spring in September and October,
when extremely cold temperatures mix with the returning sunlight to
release chlorine radicals that destroy ozone.
said that during colder years, the hole was larger, but stressed that
"this does not reverse the projected long-term recovery in the
ozone layer - which helps protect the Earth from potentially
dangerous ultraviolet rays that can cause skin damage - began
developing holes on an annual basis starting in the 1980s due to
widespread use of chlorofluorocarbons, or CFCs.
commonly used in refrigerators and aerosol cans, CFCs are now almost
non-existent thanks to an international treaty signed in Montreal in
1987, amid global concern over widening holes in the ozone layer.
year, the UN said the ozone layer was "well on track" for
recovery by mid-century, although fixing it over Antarctica would
Montreal Protocol is in place and is working well," Mr Braathen
warned though that "we may continue to see large Antarctic ozone
holes until about 2025" because of weather conditions in the
stratosphere and because ozone depleting chemicals linger in the
atmosphere for several decades after they have been phased out.