New Zealand Tries to Cap Gaseous Sheep Burps

By John Roach
for National Geographic News
May 13, 2002

New Zealand scientists trying to curb their country's influence on global warming may have found an answer to belch about: Livestock that eat plants high in condensed tannins produce up to 16 percent less methane, a potent greenhouse gas.

Tannins are the yellow-brown chemical compounds found in many plants and give red wine its distinctive flavor.

Methane is one of the three most potent gases that some scientists say are causing the Earth to warm up at an accelerated and unnatural rate. Carbon dioxide from the burning of fossil fuels is the most common greenhouse gas in the world.

"New Zealand is unique in that over 50 percent of its greenhouse gas emissions arise from methane released by enteric fermentation," said Katharine Hayhoe, an atmospheric scientist at the University of Illinois, Urbana-Champaign, Illinois.

Enteric fermentation is methane produced as part of the normal digestive process of animals, such as cows and sheep. It is primarily released in the form of burps.

The 45 million sheep and 10 million cattle in New Zealand make for a lot of burped methane—about 90 percent of that country's methane emissions, according to government figures.

For comparison, livestock are responsible for about 2 percent of the United States' greenhouse gas emissions, according to the U.S. Environmental Protection Agency.

Protocol Preparation

New Zealand plans to sign the Kyoto Protocol, an international treaty to combat global warming, this August. Under the treaty, the country must reduce its greenhouse gas emissions to 5.2 percent below 1990 levels by 2012.

Thus, any step that can be taken to reduce the impact livestock have on global warming would certainly be welcome, say researchers at AgResearch Grasslands in Palmerston North, New Zealand.

Although livestock are exempt from a tax plan unveiled by the New Zealand government in April to help meet its targets under the protocol, the agriculture industry is required to fund research on ways to reduce agriculture methane emissions.

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