The hole in the ozone layer is larger this year than in
2007.
Image: iStockphoto
The Antarctic ozone hole will be larger this year than in 2007, research by the World Meteorological Organization (WMO) has discovered.
According to the WMO 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 programmes continue to support and enhance these measurements.
“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 occasion of the International Day for the Preservation of Ozone Layer on 16 September 2008.
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/Global Atmosphere Watch (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 13 September 2008 the ozone hole covered an area of 27 million square kilometers. The maximum area reached in 2007 was 25 million square kilometers. WMO and the scientific community will use ozone observations from the ground, from balloons and from satellites together with meteorological data, to keep a close eye on the development during the coming weeks and months.
Scientists are increasingly aware of the possible links between ozone depletion and climate change. Increased atmospheric concentrations of greenhouse gases (GHGs) will lead to warmer temperatures in the troposphere and at the Earth’s surface. In the stratosphere, at altitudes where we find the ozone layer, there will be a cooling effect. A cooling of the stratosphere in winter over the last decades has indeed been observed, both in the Arctic and in the Antarctic. Lower temperatures enhance the chemical reactions that destroy ozone. At the same time, the amount of water vapour in the stratosphere has been increasing at the rate of about one per cent per year. A wetter and colder stratosphere means more polar stratospheric clouds, which is likely to lead to more severe ozone loss in both polar regions.
These observed changes in the stratosphere could delay the expected recovery of the ozone layer. It is therefore vital that funding agencies continue to support research on stratospheric ozone and harmful ultra violet radiation and that all nations with stratospheric measurement programmes continue to enhance these measurements.
Editor's Note: Original news release can be found here.
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