industry
Are Cattle in the U.S.
Causing an Increase
in Global Warming?
By Alan Rotz, USDA and Alex Hristov, Penn State Extension
Over the past decade, we have seen the media
place blame for our changing climate
on cattle. Scientific evidence does
not support this claim though for
cattle in the United States.
Cattle produce a lot of
methane gas, primarily
through enteric
fermentation and
fermentation of
their manure.
Methane
is a
powerful greenhouse gas that, along with
nitrous oxide, carbon dioxide and some other
compounds in the atmosphere, create a blanket
around our planet. This is good; without this
atmospheric blanket, the earth would be too
cold for us to survive. The current problem is that
concentrations of these gases in the atmosphere
are increasing, which is thickening our blanket.
Greenhouse gases and the atmosphere
The methane that cattle produce is part of a
natural carbon cycle that has been happening
since the beginning of life on our planet. Through
photosynthesis, carbon dioxide is extracted from
the atmosphere and fixed as carbohydrates in
plant material. Cattle consume and digest these
carbohydrates, where some of the carbon is
transformed to carbon dioxide and methane
gases that are respired back to the
atmosphere. This methane is oxidized
in the atmosphere through a series
of reactions, transforming that
carbon back to where it
started as carbon dioxide
in the atmosphere.
In contrast, when
we burn fossil
fuels, we
are
78 | AUGUST / SEPTEMBER 2019