What is known about dairy cows' emissions of greenhouse gases?
General Reference (not clearly pro or con)
The Food and Agriculture Organization of the United Nations (FAO) wrote in its 2006 report "Livestock's Long Shadow: Environmental Issues and Options," that:
"The livestock sector
emerges as one of the top two or three most significant contributors to
the most serious environmental problems, at every scale from local to
global…
With
rising temperatures, rising sea levels, melting ice caps and glaciers,
shifting ocean currents and weather patterns, climate change is the
most serious challenge facing the human race.
The
livestock sector is a major player, responsible for 18 percent of
greenhouse gas emissions measured in CO2 equivalent. This is a higher
share than transport…
The
sector emits 37 percent of anthropogenic methane (with 23 times the
global warming potential (GWP) of CO2) most of that from enteric
fermentation by ruminants [such as dairy cows]. It emits 65 percent of
anthropogenic nitrous oxide (with 296 times the GWP of CO2 ) the great
majority from manure…
In
the United States methane from enteric fermentation totaled 5.5 million
tones in 2002…overwhelmingly originating from beef and dairy cattle.
This was 71 percent of all agricultural emissions and 19 percent of the
country's total emissions."
The United States Environmental Protection Agency (EPA) wrote in its Apr. 15, 2007 report "Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2005," that:
"Agricultural activities contribute directly to emissions of greenhouse gases through a variety of processes…
In
2005, the agricultural sector was responsible for emissions of 536.3
teragrams of CO2 equivalent (Tg CO2 Eq.), or 7 percent of total U.S.
greenhouse gas emissions. Methane (CH4) and nitrous oxide (N2O) were
the primary greenhouse gases emitted by agricultural activities. CH4
emissions from enteric fermentation and manure
management represent about 21 percent and 8 percent of total CH4
emissions from anthropogenic activities, respectively. Of all domestic
animal types, beef and dairy cattle were by far the largest emitters of
CH4."
The United States Department of Energy wrote in its Dec. 2004 report, "Emissions of Greenhouse Gases in the United States 2003," that:
"At
an estimated 7.9 million metric tons of methane (182.8 million metric
tons carbon dioxide equivalent), methane emissions from agricultural
activities in 2003 represent 30.4
percent of total U.S. anthropogenic methane emissions and approximately
2.6 percent of total U.S. greenhouse gas emissions. Ninety-four percent
of methane emissions from agricultural activities result from livestock
management. Sixty-six percent of these emissions can be traced to
enteric fermentation in ruminant animals, and the remainder is
attributable to the anaerobic
decomposition of livestock wastes…
[C]attle [including beef and dairy cows] account for 95.1 percent of all emissions from enteric fermentation…"
BioEnergy Solutions, a company that develops "green energy" from cow manure, published the following in its article "Cow Power," posted on its website, (accessed Apr. 30, 2008):
"Farm animals - especially cows - produce large amounts of methane, a greenhouse gas that contributes to global warming.
Emissions
from automobiles and factories can be reduced with the installation of
sophisticated equipment. But we have yet to see a catalytic converter
or scrubbing system that will capture gases generated by cows at, shall
we say, the source...
We
capture the methane released as livestock waste decomposes, then
'scrub' it to create clean, renewable natural gas that is delivered to
power plants. The process can reduce methane emissions by up to 70%, or
an estimated 1,500 tons per year, on a 5,000-cow dairy farm.
By capturing methane that would otherwise contribute to global warming, we create a new source of domestic renewable energy."
