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Harold Brooks · April 14th 07, 11:20 PM posted to uk.sci.weather

In article , says...
Dave Cornwell wrote:

The reference you site above quotes "CFCs have ceased the increase observed
before about 1992 and have either leveled off or are in decline (Montzka et
al., 1999). The latter is a response to decreased emissions related to the
Montreal Protocol on substances that deplete the ozone layer. "

I am referring specifically to CFC's so I'm not quite sure what the less
positive view is as illustrated here?
Dave

The effect of CFC 11 has reduced very slightly since 1997, and that is good, but
the larger effect of CFC 12 has only levelled, and thus the amount of 'harm' it
is doing has remained constant, and at its peak. While a cessation of increase
is welcome, the 'damage' done, and still being done, is not (yet) reduced.

Table 2 is actually a very positive view of the CFC changes from
Montreal. Note that CFCs have long lifetimes. CFC11 went up by 40%
from 1979-1989, peaked in the early 90s and has decreased since then.
CFC12 went up by 60% from 1979-1989 and have now leveled off. In the
absence of the Montreal Protocol, the CFC12 forcing would have been ~
0.23 (instead of 0.17) and CFC11 ~0.11 instead of 0.063. More
importantly, the forcings would be continuing to increase instead of
decreasing as they will be in the future.

Harold
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Harold Brooks