The production of methane gas by ruminant animals is often
given as a reason by some people as a reason for avoiding meat to mitigate the
potential effects of methane on global warming.
The notion exists that methane is a more potent greenhouse gas than
carbon dioxide. Like so many issues
surrounding agriculture, a little knowledge is dangerous and leads many people
to the wrong conclusions. It even led to
the New Zealand Government at one point considering a financial penalty for the
farming of ruminant animals.
There is a popular belief that methane is something like 20
to 25 times more potent than carbon dioxide – an example of how if you repeat a
lie enough times people start believing it.
Here are a few facts:
- · Carbon dioxide is nearly three times heavier than methane so if equal volumes of the gases are compared rather than weights it is evident that the warming ability of methane is grossly overstated.
- · Carbon dioxide remains in the atmosphere for hundreds of years whereas methane has a half-life of around eight years converting into carbon dioxide and water.
- · There appears to be little correlation between methane levels and the number of ruminants on the planet. Increases in the number of ruminant animals has resulted in no corresponding increase in methane levels in the atmosphere.
·
Livestock agriculture contributes between 15%
and 28% of global methane emissions from human activity. The balance comes from activities such as
rice growing, landfills and pipeline leaks.
Having discussed the relative potency of methane and carbon
dioxide, perhaps the most important point is that in many ways it is
irrelevant. I raise livestock in the
rangelands of Australia where there are few alternative land uses and cattle
are raised in close as possible to a natural environment. It is one of the most benign forms of food
production. The vegetation that grows
here would be eaten or broken down by something. In our case it is cattle converting the grass
to meat – if the cattle were not there the grass would be eaten by termites or
broken down by microorganisms releasing methane into the atmosphere.
The digestion performed by ruminant animals is truly a
miracle of nature which brings into agricultural production land that would
otherwise be unsuitable for production. It
is a form of food production which should be promoted rather than the
opposite.
FURTHER READING
Brill, Barry (2011)
Methane: myths and
misrepresentations. http://quadrant.org.au/opinion/doomed-planet/2011/05/barry-rill-methane/
