[asa] A Response to the BBC Documentary on The Great Warming Swindle-2

2. The documentary suggests that human contributions to carbon dioxide
levels in the atmosphere are very small - even negligible one might infer. They
suggest that volcanoes, and vegetative decay and the oceans are by far the
larger source of carbon dioxide.
Response: This is true, although their claim about volcanic sources of carbon
dioxide are much over-stated; the primary effect of volcanic activity is
cooling due to their high atmospheric emissions of small particulate matter
which scatters sunlight and decreases the amount of solar radiation reaching
the earth. In fact much of the cooling due to the “little ice age” in the
1700s is believed to be attributable to relatively high levels of global
volcanic activity during this time period.
They also quote Prof Carl Wunsch (MIT) as a source regarding the warming
oceans as a source of CO2 (gases become less soluble in water as the water
warms - Henry’s Law). But when Prof. Wunsch talked to Martin Durkin, he
stressed that because a warming ocean releases CO2 there was very good reason
to be concerned about the current increase in global average temperatures
because this will (later) lead to even higher levels of CO2 in the atmosphere
due to release of this gas from the warming oceans, thereby producing a
positive feedback effect and entailing even more warming (see
http://www.realclimate.org/index.php/archives/2007/03/swindled/ response
#109 for a copy of Wunsch’s letter to Durkin). So Wunsch was quoted but very
much out of the context in which he made his quotes to the interviewer.
It is true that human combustion of fossil fuels contributes a relatively
small amount of CO2 to the planet’s climate budget - maybe about 5%. But all
of the rest of the CO2 is part of natural cycles the circulate carbon through
the planet’s systems and keeps things more or less balanced. That is why cows
and animals should not be understood as main contributors to climate change;
generally they eat grasses and grains that remove CO2 from the atmosphere and
return such CO2 (along with some methane) when they undergo respiration. But
fossil fuel combustion places an additional input of CO2 into the atmosphere
(carbon that was removed by plants and animals millions of years ago and fixed
in the ground) that is not balanced by an additional mechanism for removal of
CO2 from the atmosphere. So human use of fossil fuels places greater intensity
on the already existing CO2 removal mechanisms which, it seems, are inadequate
to remove all of the additional CO2 we add each year. Hence human use of fossil
fuels contributes to rising carbon dioxide levels in the atmosphere.

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 11:34:17 2007