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United
Nations Environment Programme |
Press Release - Ozone Day 2000
(For use of the information media-not an official record) WMO-N°652
Update on this Year's Antartic Ozone Hole on the Occassion of the International Day for the Preservation of the Ozone Layer
Unprecedented rate of ozone loss measured one to two weeks earlier over and near Antarctica.
Geneva, 15 September 2000 -- Measurements confirm that ozone over and near Antarctica is decreasing more rapidly this year than in previous years. The total amount and the rate of ozone loss varies considerably from year to year. These large variations are expected and are primarily due to meteorological variations in the stratosphere. For more than a decade, the annual Antarctic ozone hole has predictably appeared in late August or early September, the period when the first sunlight appears in the Antarctic region after the total darkness of winter. Consequently, the ozone hole is characteristically growing rapidly at this time.
The year to year variations in the intensity of ozone loss and its duration are carefully monitored at WMO Global Atmosphere Watch (GAW) stations and by satellites. The loss this year is one to two weeks ahead of all previous years. Another important measure of the ozone loss is made by comparing this year's measurements to the 1964-76 pre-ozone hole norms (1998 WMO Scientific Assessment of Ozone Depletion). This year, Antarctic stations have recorded ozone values more than 50% below the pre-ozone hole norms, and satellite ../images confirm that these large losses are widespread within the ozone hole. Overall, the average decrease from the norms within the ozone hole is 35-40% wherever there is sunlight. Although ozone decreases of this magnitude and larger are common during each ozone hole season, it is remarkable to find these low values so early in September, one or two weeks earlier than in any previous year.
For August, satellite ozone measurements averaged over the month show ozone was also exceptionally low outside the vortex region. A comparison of latitude bands between the Antarctic vortex and latitude 50° S with all satellite data from previous years, shows this year's ozone level to be the lowest on record for the month of August, with figures 10% to 20% below the pre-ozone hole norms. Ozone levels farther north are typical of recent years and near historical norms.
In recognition of the importance of international co-operation on environmental issues that affect all the countries of the world and to commemorate the date of the historic signing of the Montreal Protocol in 1987, 16 September has been designated by the United Nations as International Day for the Preservation of the Ozone Layer. On this occasion, Prof. G.O.P. Obasi, Secretary-General of WMO urged nations of the world to pursue their efforts in the implementation of the Vienna Convention on the Protection of the Ozone Layer and the Montreal Protocol and Amendments on Substances that Deplete the Ozone Layer and in particular maintain the monitoring networks. The landmark agreement of 1987 was an appropriate response to the announcement of the unexpected appearance of the Antarctic ozone hole in the mid-1980s. Careful analysis of the historical datasets available confirmed that substantial ozone loss was occurring above the entire Antarctic continent. The controls that have been put into place since 1987, are expected to reduce these losses to pre-1980 values in the coming decades, perhaps by the year 2050.
In any case, prevailing meteorological conditions in the stratosphere, particularly during the austral spring, strongly influence the overall extent of ozone decreases and may substantially limit the total seasonal depletion within the ozone hole this year.
For more information please contact:
Taysir Al-Ghanem,
Chief, Information & Public Affairs
World Meteorological Organization (WMO)
7 bis, Avenue de la Paix, CH-1211 Geneva 2,
Switzerland
Tel: (41 22) 730 8315 Fax: (41 22) 7308027
E-mail: Al-Ghanem_T@gateway.wmo.ch
http://www.wmo.ch
Dr Michael Proffitt, Senior Scientific Officer, WMO Global Atmosphere Programme
at proffitt@wmo.ch
for scientific questions
