The Montreal Protocol

The chlorofluorocarbons (CFCs) are greenhouse gases whose emissions into the atmosphere are already controlled under the Montreal Protocol on ozone-depleting substances. This control has not arisen because of their potential as greenhouse gases, but because they deplete atmospheric ozone (see Chapter 3). Emissions of CFCs have fallen sharply during the last few years and the growth in their concentrations has slowed; for some CFCs a slight decline in their concentration is now apparent. The phase-out of their manufacture in industrialised countries by 1996 and in developing countries by 2006 as required by the 1992 amendments to the Montreal Protocol will ensure that the profile of their atmospheric concentration will continue to decline. However, because of their long life in the atmosphere this decline will be slow; it will be a century or more before their contribution to global warming is reduced to a negligible amount.

The replacements for CFCs - the hydrochlorofluorocarbons (HCFCs), which are also greenhouse gases though less potent than the CFCs - are required to be phased out by 2030. It will probably be close to that date before their atmospheric concentration stops rising and begins to decline.

Because of the international agreements that now exist for control of the production of the CFCs and many of the related species that contribute to the greenhouse effect, for these gases the stabilisation of atmospheric concentration required by the Climate Convention will in due course be achieved.

Other replacements for CFCs are the hydrofluorocarbons (HFCs), which are greenhouse gases but not ozone-depleting. The controls of the Montreal Protocol do not therefore apply and, as was mentioned in Chapter 3, any substantial growth in HFCs needs to be evaluated along with the other greenhouse gases. As we shall see in the next section, they are included in the 'basket' of greenhouse gases addressed by the Kyoto Protocol.

0 0

Post a comment