Geology Reference
In-Depth Information
Effect of the Montreal Protocol
20000
Effective stratospheric
chlorine
Montreal
1987
15000
10000
No protocol
London 1990
5000
Copenhagen
1992
Beijing
1999
Zero emissions
0
1980
2000
2020
2040
2060
2080
2100
Year
Figure 27 Predictions for the future abundance of effective stratospheric chlorine are
shown in (1) the assuming no Protocol regulations, (2) only the regulations in
the original 1987 Montreal Protocol and (3) additional regulations from the
subsequent Amendments and Adjustments. The city names and years indicate
where and when changes to the original 1987 Protocol provisions were agreed
upon. Effective stratospheric chlorine as used here accounts for the combined
effect of chlorine and bromine gases. The ''zero emissions'' line shows strato-
spheric abundances if all emissions were reduced to zero beginning in 2003
58
Figure 29 shows a recent picture of the ozone hole taken from space.
Strictly speaking the use of the word ''hole'' to describe what happens to
ozone in the Antarctic is an exaggeration. There is undoubtedly a
massive depletion of ozone, particularly between 12 and 20 km in the
Antarctic stratosphere (up to 100%) but the total column of ozone is
depleted rather than removed altogether (see Figure 28). The exact
location and size of the hole varies with meteorological conditions, but
the area covered has increased over the past 10 years or so (see Figure
30). Currently, in the austral spring the hole extends over the entire
Antarctic continent, occasionally including the tip of South America,
covering an area equivalent to the North American continent (ca. 22
million km
2
) (see Figure 31).
