[asa] A Response to the BBC Documentary on The Great Warming Swindle-3

3. The documentary claims the CO2 is a very minor gas in the atmosphere
and it claims that it is a minor greenhouse gas. The implication is that one
should not expect such a minor atmospheric gas to be able to contribute to a
warming climate.
Response: It is true that CO2 is a trace gas in the dry atmosphere. Currently
it makes up about 0.0384% of the dry atmosphere – but that is up from about
0.0280% in 1880 (a 36% increase). But the documentary fails to acknowledge
that, although a trace gas, CO2 makes up about 99% of the greenhouse gases in a
dry atmosphere. Nitrogen, oxygen and argon which together make up about 99.9%
of the gases in a dry atmosphere are not greenhouse gases and do not contribute
to warming. So it is not unreasonable to expect that an increasing level of the
main greenhouse gas in the dry atmosphere will lead to absorption of more heat
energy radiating from the surface of the earth. There are other greenhouse
gases (methane, nitrous oxide, CFCs, CHFCs, SF6) at much lower levels than CO2
in the dry atmosphere that also contribute to warming. It is true that water
vapor is the most important greenhouse gas. But the level of water vapor in the
air is strongly variable from day to day depending on the weather. Sometimes
its level is so high (humid days) that it is responsible for nearly all of the
greenhouse warming; at other times its level is much lower (high pressure
systems, winter) and then it contributes a smaller fraction to warming and the
other trace greenhouse gases proportionately more.
Moreover, warming of the atmosphere (and later, the oceans) due to human use
of fossil fuels will lead to higher average water vapor levels in the
atmosphere and therefore, very likely, greater warming (positive feedback).
This is a reality that is already being observed: “The average atmospheric
water vapour content has increased since at least the 1980s over land and ocean
as well as in the upper troposphere. The increase is broadly consistent with
the extra water vapour that warmer air can hold.” {3.4} – IPCC-FAR-SPM).

Ken Piers

"We are by nature creatures of faith, as perhaps all creatures are; we live by
counting on things that cannot be proved. As creatures of faith, we must choose
either to be religious or superstitious, to believe in things that cannot be
proved or to believe in things that can be disproved."
Wendell Berry

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Received on Wed Mar 21 11:36:17 2007