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
