Described first 1956 by G.M.B. Dobson the ozone hole put the international community into action. The Montreal Protocol signed by 24 countries and by the European Community in September 1987 was one of the first successful international agreements regarding the environment.
Ozone depleting substances like chlorofluorocarbons, halons, carbon tetrachloride, hydrochlorofluorocarbons, hydrobromofluorocarbons and methyl bromide will phase out at last 2020 by developed and 2040 by developing countries.
This years hole in the Antarctic ozone layer was the most serious on record exceeding that of 2000. Not only was it the largest in surface area (matching 2000) but also suffered the most mass deficit, meaning that there was less ozone over the Antarctic than ever previously measured.
Measurements were taken from instruments on both NASA and European Space Agency (ESA) satellites. These are validated by surface based observations
of the WMO Global Atmosphere Watch (GAW) ozone network.
Each agency uses different instruments hence the slightly different values.
NASA instruments showed that, on 25 September 2006, the area of the hole reached 29.5 million km2, compared to 29.4 million km2 reached in September 2000.
According to ESA, the ozone hole area reached 28.0 million km2 on 25 September 2006, very close to the maximum in 2000, which peaked at 28.4 million km2
The ozone mass deficit in 2006 was measured at 39.8 megatonnes on 1 October, higher than in 2000, which peaked at 39.6 megatonnes on 29 September. Mass deficit is the amount of ozone missing from a vertical column of air compared to a baseline measured many decades earlier before severe ozone depletion appeared.
This years hole was caused by the continuing presence of peak levels of ozone destroying substances in the atmosphere combined with a particularly cold stratospheric winter.
3rd October, World Meteorological Organization (WMO)
UNEP: OzonAction Education Pack, Regional Networks, WMO Ozone Bulletins
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