Ozone Depletion and Climate Change
Ozone depletion and climate change have usually been thought of as environmental issues with little in common other than their global scope. The climate system involves the atmosphere - specifically processes within the troposphere, such as air circulation patterns - land surfaces and oceans. The ozone layer is found in the stratosphere, which is the layer of the atmosphere immediately above the troposphere.
Climate change is a long-term shift in climate measured by changes in temperature, precipitation, winds, and other indicators. Climate change can involve both changes in average conditions and changes in variability, including, for example, changes in extreme conditions.
Climate change is concerned with how carbon dioxide, methane, and other greenhouse gases are altering the global climate system. Ozone depletion, on the other hand, involves how certain industrially produced chemicals containing chlorine or bromine are damaging the earth's protective stratospheric ozone layer. However, as the global community has come to understand more about these issues, and the complex physical and chemical processes that drive them, we have become increasingly aware of the ways in which actions to address each are interlinked. The most obvious linkage between efforts to mitigate ozone depletion and climate change is the fact that certain ozone-depleting substances (ODS) such as chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) are also powerful greenhouse gases.
In addition, hydrofluorocarbons (HFCs) and other halocarbons, which do not deplete the ozone layer but are greenhouse gases, are currently commonly used as alternatives to CFCs and HCFCs. This illustrates the need to consider the implications for both issues when choosing alternatives to ODS, and to consider environmental impact as an important factor, in addition to technical and financial feasibility.
Another important linkage involves the way that ozone-depleting substances and greenhouse gases alter certain processes in the atmosphere so as to enhance both global warming and stratospheric ozone depletion. These changes result in a warming of the troposphere and a cooling of the stratosphere. Stratospheric cooling is a key factor in the development of ozone holes over the poles.
It is clear that actions to mitigate global warming can have positive effects on ozone depletion and vice versa. However, care must be taken to avoid solutions to one problem that make the other worse.
Find Out About...
- Canada's Action on Climate Change
- Safeguarding the Ozone Layer and the Global Climate System: Issues related to hydrofluorocarbons and perfluorocarbons (Intergovernmental Panel on Climate Change Special Report)
- The importance of the Montreal Protocol in protecting climate (Journal article - Proceedings of the National Academy of Sciences of the United States of America)
- The large contribution of projected hydrofluorocarbon emissions to future climate forcing (Journal article - Proceedings of the National Academy of Sciences of the United States of America)
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