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

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