Day 011 - 12 Jul 94 - Page 39


     
     1        in the North of England and in Scotland (which are
              primarily covered by clouds) there is virtually no photo
     2        chemical smog at the moment.
 
     3   Q.   Mr. Lipsett suggested yesterday that pentane had been
              identified as having a role as a greenhouse gas.  Would
     4        you care to comment on that?
              A.   Yes, in principle if one were to look at the
     5        absorption bands of hydrocarbons, because they occur in
              roughly the same wavelength region as those of methane,
     6        one could argue that it might behave as a greenhouse gas.
              However, because pentane belongs to a group which are
     7        classified in UK reports as non-methane hydrocarbons (in
              other words hydrocarbons other than methane) these are, in
     8        fact, extremely reactive in the lower atmosphere and under
              most circumstances do not survive long enough to act as a
     9        substantial greenhouse gas.
 
    10   Q.   I would like to move, if I may, from pentane to methane
              which you have just mentioned.  You told us earlier that
    11        of the greenhouse gases, carbon dioxide was by far the
              largest in terms of proportion in the atmosphere.  Is that
    12        right?
              A.   Yes.
    13
         Q.   Was it 70 per cent or more?
    14        A.   Yes, it is of that order of magnitude.
 
    15   Q.   I think the figure you gave for methane was about 14 per
              cent.
    16        A.   Yes.
 
    17   Q.   Do you know how much in metric tonnes weight methane is
              emitted annually into the world's atmosphere?
    18        A.   It is about 550 metric tonnes.
 
    19   Q.   Do you know what proportion of that 550 metric tonnes ----
              I will ask it a different way.  Do you know how many
    20        tonnes are emitted by, what is called, enteric
              fermentation of animals?
    21        A.   About 80 million.
 
    22   Q.   This is 80 million metric tonnes.
              A.   80 million metric tonnes of that 550 comes from
    23        enteric fermentation by animals.
 
    24   Q.   Which animals emit methane in the process of enteric
              fermentation?
    25        A.   The primary animals are cows, sheep, elephants and
              other natural animals which, in the past, would have been 
    26        buffalos. 
  
    27   Q.   Are these ruminants?
              A.   Yes.
    28
         Q.   We humans, who do not ruminate, do not emit much methane,
    29        or any at all, is that right?
              A.   We do emit a bit of methane, but not very much.
    30
         Q.   Do you know of animal emission of methane what amount is

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