Day 011 - 12 Jul 94 - Page 35
1 is to talk about the active and inactive chlorine in the
stratosphere.
2
Q. Is this the first time in any of these SORG reports that
3 chlorine loading had been used as a measure?
A. Yes.
4
MR. JUSTICE BELL: The concept was known. It was just which
5 was the most helpful way to compare them, was it?
A. The concept was known. I think that the difference
6 between 1988 and 1990 was that people were not quite so
confident that they had identified all the reaction
7 channels which were necessary if you were going to use
ozone depleting potential, whereas the idea that once
8 substances were transported into the upper atmosphere, it
took so long for the substances to get out of the upper
9 atmosphere that once the chlorine-containing species got
there, then effectively all of them had the potential to
10 damage the upper atmosphere. It is not that, in fact,
ozone depleting potential is not used; it is, in fact,
11 still used. It still has some validity. However, it was
felt that this alternative way of looking at the scenario
12 had some benefits and it was commended to the British
government by the group who wrote the report.
13
MR. RAMPTON: Can I ask you to look at another two short
14 paragraphs here.
15 "8. Chlorine loading has doubled since 1973 and, under
the existing terms of the Montreal Protocol, it will
16 continue to rise throughout the next century. Priority
should be given to halting this rise. Prompt action to
17 scale down releases of currently controlled substances
could hold peak loading below 4 ppbv.
18
"9. To reduce the chlorine loading in the second half of
19 the next century to values between 1.5 and 2 ppbv, such as
prevailed before the appearance of the Antarctic ozone
20 'hole' requires a rapid phase out of all the long-lived
halocarbons, and a subsequent phase out of short-lived
21 halocarbons."
22 Professor Duxbury, as between CFC- 12, for example, and
HCFC- 22, which falls into which category - long-lived and
23 short-lived?
A. CFC-12 falls into the long- lived category and HCF-22
24 into the short-lived category.
25 Q. There is a mention on carbon tetrachloride in paragraph
11. Paragraph 12,
26
"The short-lived halocarbons capable of carrying chlorine
27 to the stratosphere must be controlled if the benefit of
cutting CFCs is not to be lost. Some are already in use
28 (e.g. Methyl chloroform) and others are being developed as
substitutes for CFCs (HCFCs).
29
"13. Substitution of CFCs by HCFCs in other than modest
30 proportion, depending on the lifetime of the particular
HCFC used, could both increase the peak chlorine loading
