WMO Encourages Members to Monitor Ozone Hole

"After decades of chemical attack, it may take another 50 years or so for the ozone layer to recover fully. As the Montreal Protocol has taught us, when we degrade our environment too far, nursing it back to health tends to be a long journey, not a quick fix," said Ban Ki-moon, secretary-general of the United Nations, on the International Day for the Preservation of Ozone Layer (Sept. 16).

According to the World Meteorological Organization (WMO), the 2008 Antarctic ozone hole will be larger than the one of 2007. The observed changes in the stratosphere could delay the expected recovery of the ozone layer. It is therefore vital that all Member States with stratospheric measurement programs continue to support and enhance these measurements.

Routine ozone measurements in all parts of the world using surface-based spectrophotometers, balloon-borne sensors, aircraft and satellites have been made by the National Meteorological and Hydrological Services of WMO Members and partners worldwide since the 1950s. Thirty years later, comprehensive measurements started under coordination of the WMO Global Atmosphere Watch (GAW). These measurements have been critical to the series of Scientific Assessments of Ozone Depletion published since the mid-1980s by WMO and the Ozone Secretariat of the United Nations Environment Programme documenting progress made under the Vienna Convention for the Protection of the Ozone Layer. The most recent of these assessments came out in the spring of 2007. The work on the next ozone science assessment will begin in the middle of 2009.

In 1985, the Vienna Convention was signed by 22 countries. Two years later, the Montreal Protocol was signed on Sept. 16, a day which has since been designated by the United Nations as International Day for the Preservation of the Ozone Layer. The theme for 2008 is "Montreal Protocol - Global partnership for global benefits."

At the end of August 2008, WMO released its first of the 2008-series bi-weekly Antarctic Ozone Bulletin on the current state of stratospheric ozone in the Antarctic. These bulletins use provisional data from the WMO/GAW stations operated within or near the Antarctic, where the most regular and dramatic decreases in ozone occur.

According to the latest bulletin, the vortex is presently more circular than at the same time last year. This has led to an onset of ozone depletion that is close to the 1979-2007 average and somewhat later than last year, when the vortex was more elongated and more exposed to sunlight. The meteorological conditions observed so far could indicate that the 2008 ozone hole will be smaller than that of 2006 hole but larger than that of 2007.

Usually, the Antarctic ozone hole reaches its maximum intensity in late September/early October. In 2008, the ozone hole appeared relatively late. However, during the last couple of weeks it has grown rapidly and has now passed the maximum size attained in 2007. Since the ozone hole is still growing, it is too early to determine how large this year's ozone hole will be. On Sept. 13, 2008 the ozone hole covered an area of 27 million square kilometers. The maximum area reached in 2007 was 25 million square kilometers.

Scientists are increasingly aware of the possible links between ozone depletion and climate change, which delay the expected recovery of the ozone layer. It is therefore vital that funding agencies continue to support research on stratospheric ozone and harmful ultraviolet radiation and that all nations with stratospheric measurement programs continue to enhance these measurements.

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