e-Digest Statistics about: Ozone Depletion
Action to Limit Ozone Depleting Substances
International agreement to limit the production and consumption of ozone depleting substances was reached in 1987 under the Montreal Protocol on Substances that Deplete the Ozone Layer. The provisions have been strengthened a number of times since 1987, most recently in November 1999 (Beijing Amendment). Table 10 shows the current reduction and phase out requirements for developed countries under the Montreal Protocol. It also shows the requirements which apply in the EU under the provisions of EC Regulation 2037/00 on Substances that Deplete the Ozone Layer. The new EC Regulation was introduced in 2000 to take account of the tighter controls introduced for HCFCs and methyl bromide by the Protocol in 1995 and 1997.
The Montreal Protocol has led to substantial reductions in the production and consumption of ozone depleting substances. In terms of ozone-depleting potential (ODP) tonnes, developed countries have reduced over 95% of their consumption of all ODS, while developing countries have globally reduced their consumption by around 50%. Data on the production and consumption of ozone depleting substances in the UK over this period are given in Table 11. Further details of reported production and consumption in other countries party to the Protocol may be found on the web site of the UNEP Ozone Secretariat [25]. UK supply of CFCs and of substitute HCFCs and their use is given in Table 12.
The concept of the combined chlorine and bromine loading of the atmosphere provides a useful measure of the potential damage to the ozone layer arising from halocarbon emissions (Table 13). Atmospheric measurements suggest that as a result of global compliance with the current provisions of the Montreal Protocol, the total equivalent chlorine loading peaked in the mid-1990s at around 4.7 parts per billion by volume (ppbv), after more than doubling over the previous two decades, before starting to decline. It is anticipated that the atmospheric loading will return to pre-Antarctic ozone hole levels of 2.8 ppbv by the middle of this century with a coincident recovery of the stratospheric ozone layer [17]. The natural background amount is estimated to be about 0.9 ppbv equivalent chlorine loading. There is increasing evidence that climate change has an impact on ozone and may delay recovery. For example, the cooler stratosphere associated with climate change assists the development of polar stratospheric clouds which subsequently increase ozone loss.
The Universities of Bristol and East Anglia measure a wide range of ozone depleting substances and their replacements at Mace Head in Ireland (Table 14, Key Fact). The Met Office has analysed the Mace Head data and identified trends in concentrations of ODS. The concentrations of two of the principal ozone-depleting CFCs, CFC-11 and CFC-113, and of ethyl chloroform (CH3CCl3) and carbon tetrachloride (CCl4), are declining. Observed CFC-12 concentrations, which has been increasing in recent years, are now declining. . There is a sustained growth in concentrations of HFCs and HCFCs, which have replaced CFCs in some applications. (HFCs are not ozone depleting gases but are powerful greenhouse gases that contribute to global warming – see Understanding the Causes of Climate Change.)In Detail:
- Stratospheric Ozone Depletion and Possible Impacts of Ozone Depletion in the UK
- Understanding Stratospheric Ozone Depletion
Further Information:
- Key Facts:
- Column ozone in the UK
- Atmospheric concentrations of ozone depletors
- World and UK consumption of CFCs
Data Tables:
- References, further reading and links to other resources:
- [17] Department of the Environment, (1996). Stratospheric Ozone, 1996. United Kingdom Stratospheric Ozone Review Group
- [19] Department of the Environment, (1996). The Potential Effects of Ozone Depletion in the United Kingdom. United Kingdom UVB Measurements and Impacts Review Group Second Report. TSO
- [20] Department for Environment, Food and Rural Affairs, (2003) The Ozone Layer
- [25] United Nations Environment Programme (2002), Report of the Secretariat: Production and Consumption of Ozone Depleting Substances (ODS) under the Montreal Protocol 1986-2000 http://www.unep.org/ozone
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Page last modified: 6 November 2007
Page published: 10 September 2003