Cow burps make for bad air Down Under

Gastronomical emissions: Cows, which have doubled in population in the last 40 years to an estimated 1.3 billion worldwide, produce one pound of methane for every two pounds of meat that they yield

July 21, 2000
Web posted at: 12:27 p.m. EDT (1627 GMT)

By Environmental News Network staff

A burping cow is a polluting cow.

Belching and flatulence in cows and sheep annually produce 90 percent of Australia's methane emissions in the agricultural sector, a recent study shows.

In an effort to monitor Australia's national greenhouse gas inventory, Australian researchers went about calculating methane emissions from belching bovines and other livestock. Under the United Nations Framework Convention on Climate Change, Australia has an obligation to report on greenhouse gas emissions, which include methane. All countries that are signatories to the convention are required to produce inventories of greenhouse gas emissions to demonstrate whether agreed target reductions over the period 1990 to 2010 are being met.

"The map is a tool to verify Australia's methane emissions," said Simon Bentley, a scientist at CSIRO's division of Atmospheric Research. "To create the methane map, we calculated how emissions vary from place to place and between seasons."

Cows, which have doubled in population in the last 40 years to an estimated 1.3 billion worldwide, produce one pound of methane for every two pounds of meat that they yield. Methane is 25 times more potent than carbon dioxide in contributing to global warming.

In addition to gas produced by livestock, sources of methane emissions include fossil fuel extraction and waste disposal as well as natural sources such as wetlands and termites.

Sheep also contribute to methane levels in the environment

Australia's cattle and sheep produce six and a half billion pound of methane a year, the map shows.

"Most of the livestock methane comes from cattle and sheep burps, with a small additional source being animal wastes," Bentley said.

Bacteria in the intestines of the animals break down the food they eat, converting some of it to methane gas, he explained.

A typical cow burps about 280 liters of methane each day. Researchers have discovered that the amount of methane produced by a cow varies dramatically according to the quality of its diet.

Animals fed on poor meal, common in warm climates, generate significantly more gas and produce less meat and milk.

Researchers found that better diets lead to improved production from the animals, which translates to faster growth and a greater yield of milk and meat. To date, there is no legislation that governs what livestock are fed in Australia.

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CSIRO's division of Atmospheric Research
Cow belching
EPA's site onGlobal warming
United Nations Convention on Climate Change
Belch.Com

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