16 September – International Day for the Preservation of the Ozone Layer 

ANTARCTIC OZONE HOLE UNUSUALLY LARGE 

Geneva, 16 September 2003 – According to the World Meteorological Organization (WMO), measurements over and near Antarctica show that ozone is decreasing more rapidly this year than in previous years and that the size of the ozone hole is now as large as the all time record size of 28 million sq. km during September 2000. This is in stark contrast to the ozone hole last year when it was the smallest in more than a decade after splitting in two during late September.

 In recent years, the ozone hole is at or near its maximum size during mid-September, with the maximum sometimes reached in late September. It cannot be predicted with certainty whether the ozone hole will continue to grow during the next few weeks. Recent variations in size, depth and persistence of the ozone hole are due to year-to-year changes in meteorological conditions in the lower stratosphere over Antarctica, rather than changes in the amount of ozone depleting chemicals present in the ozone layer. 

The use of ozone depleting chemicals is presently being controlled through the enforcement of international agreements. Measurements show that most of these chemicals are decreasing in the lower atmosphere and they appear to have reached their peak in the critically important ozone layer in the stratosphere. There is a delay in the cleansing of these chemicals from the ozone layer, and it is expected to require decades before the stratosphere returns to pre-ozone hole conditions. Complete recovery of the ozone layer will require continuing diligence with the enforcement of the international agreements. 

In recognition of the importance of international co-operation on environmental issues and to commemorate the date of the 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 all nations to pursue their efforts in the monitoring of the chemical composition of the atmosphere and 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. 

For more information, please contact: Ms Carine Richard-Van Maele or Dr Michael Profitt Chief, Information and Public Affairs Senior Scientific Officer World Meteorological Organization World Meteorological Organization 7, bis Av. De la Paix 7, bis Av. De la Paix CH-1211 GENEVA 2 CH-1211 GENEVA 2 Tel: + 41 22 730 83 14/15 Tel: + 41 22 730 8235 Fax: + 41 22 730 80 27 

E-mail : proffitt_m@gateway.wmo.ch E-mail: vanmaele@gateway.wmo.ch