Part 1: Introduction
Carbon dioxide is not the only greenhouse
gas whose presence in the atmosphere is blamed
on Mankind. Another is methane (CH4). And so,
after a mountain of evidence showed that carbon
dioxide levels above 300 ppm do not cause
global warming, [1] climate fear-mongers looked
for another man-made product that might bolster
their cause. They came up with methane as an
even more serious ‘warmer’ than
carbon dioxide. And methane levels, we are
told, have already doubled. The main
‘new’ sources of methane are from
our agriculture, largely from our herds of
cattle and from flooded rice paddies. Adding to
these, but in smaller amounts, are emissions
from waste dumps and leaks from coal mining and
natural gas production.
The IPCC’s Summary for Policy Makers
2007 stated:
‘The global atmospheric concentration
of methane has increased from a pre-industrial
value of about 715 ppb to 1732 ppb in the early
1990s, and is 1774 ppb in 2005. The atmospheric
concentration of methane in 2005 exceeds by far
the natural range of the last 650,000 years
(320 to 790 ppb) as determined from ice cores.
Growth rates have declined since the early
1990s, consistent with total emissions (sum of
anthropogenic and natural sources) being nearly
constant during this period. It is very likely
that the observed increase in methane
concentration is due to anthropogenic
activities, predominantly agriculture and
fossil fuel use, but relative contributions
from different source types are not well
determined.’[2]
As a consequence, many
‘warmers’ took note of the first
part of this, neglecting the latter half, and
called for humans to reduce their intake of
meat. Naturally, vegetarians also climbed on
the bandwagon, and there was a spate of
newspaper articles in western countries.
The case against methane stems from a claim
that past emissions currently contribute 15-20%
of the enhanced greenhouse effect and
reinforced by another: that, although it
started later than the rise in CO2, a current
large increase in emissions of methane means
that its contribution has been catching up fast
despite the fact that a recent study by
Dlugokencky, et al shows that atmospheric
methane was at a steady state of 1751 ppbv
between 1999 and 2002.”[3] EPA used ppbv
(parts per billion by volume) because that
gives a much bigger number (1.75 parts per
million looks a bit insignificant compared to
385 parts per million for CO2).
Methane, then, has given the
‘warmers’ something else to
attack in our society.
And we should all become veges to save the
planet.
But how important is methane as far as
possible climate change effects?
Part 1: Introduction | Part 2:The IPCC’s
Argument | Part 3:
Methane chaos | Part
4: Science and references
|
