The Montreal Protocol 245increased by around thirty-seven per cent (China and India by about
nineteen and sixty-eight per cent respectively).
As we shall learn later in the chapter, stabilisation of carbon dioxide
emissions would not lead in the foreseeable future to stabilisation of
atmospheric concentrations. Stabilisation of emissions could only be a
short-term aim. In the longer term much more substantial reductions of
emissions are necessary.
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 hydrochloro-fluorocarbons
(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 which 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.