Tue Mar 09, 2004
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Methane is a potent greenhouse gas, and believe it or not, a significant portion of it comes
from the belches of domestic livestock.
Hi, I'm Bryan Yeaton, and this is The Weather Notebook's weekly climate change series.
The burps and -- well, the front-end and the back-end burps -- of sheep, cattle, goats,
camels, and horses, make up about 15 percent of the world's methane emissions.
Pound-for-pound, methane has a much greater potential to warm the atmosphere than does carbon
dioxide. In fact, about one-third of global warming is independent of fossil fuel burning, and
much of that is due to methane.
Which brings up back to sheep and cows. Scientists who've studied the subject-which means
hooking up cows' noses to vacuum hoses-have found that the average dairy cow produces about
200 pounds of methane a year. That means a good-sized herd of about 200 cows produces as much
greenhouse gas in a year as a car driven five times around the globe.
This is a big problem for countries like New Zealand. In fact, more than half of that
country's greenhouse gas emissions comes from sheep and cow burps, and they're anxious to
reduce the gasses to comply with the Kyoto Protocol. So agricultural researchers have been
experimenting with livestock feed that can produce less methane.
The early news is promising: pasture plants high in condensed tannins, the compound that helps
give red wine its distinctive taste, produce up to 16 percent less methane in the animals that
eat it. But don't be too cowed by this information: in the United States, livestock are
responsible for only two percent of greenhouse gas emissions.
Today's show was sent in by David Appell. Our show is funded by Subaru of America and the
National Science Foundation. Thanks also to Davis Instruments, at www.davisnet.com.