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Science
Friday > Archives
> 1997
> December
> December 5, 1997
Hour One: Greenhouse Gases: The Overlooked Sources:
The debate over global warming usually focuses on big industry. But what about other sources, from cows to that shiny new sport utility vehicle in your driveway?
The Kyoto conference on climate change is in full swing. But after they deal with the tough political question of how much to limit emissions of gases like carbon dioxide and methane, the nations involved will have to develop practical methods for cutting back production of these greenhouse gases. The main greenhouse gas that the delegates are examining is carbon dioxide, which is emitted primarily through combustion of carbon-based fuels. Two hundred times as much carbon dioxide as methane is emitted each year, but molecule for molecule, methane is about fifty times more effective at warming the planet. And while much of the global warming debate has focused on huge projects like developing cleaner methods of electricity generation or stopping deforestation, a big difference could come from relatively small sources of methane - like cows. | Cows can only digest some foods after a fermentation process, called rumination. During this process, bacteria in the cow's stomach produces methane gas. In fact, in ordinary cows, 2-12% of the energy from food is used to produce methane. And while the digestive difficulties of one burping cow may not seem like a big deal, the cumulative effects of 1.3 billion cattle producing over 100 million tons of methane annualy can have a significant effect on the world's balance of greenhouse gases. Human-related processes, from energy production to agriculture, produce approximately 60% of the world's methane. Ruminant animals such as cattle, buffalo, and sheep, are estimated to produce approximately a quarter of that tally, or 15% of the world's total supply. | 
photo courtesy of the
National Cattlemans' Beef Association | 
Cow wearing methane
monitoring device
(photo courtesy of Hal Westberg,
Washington State University) | Programs have been in place for several years to monitor the methane output of cows, and to try to develop ways of reducing methane production. Studies have found that poor nutrition is one reason for excess methane production - supplementing a cattle diet with urea has been found to lower methane production by 25-75%. Diet adjustments can also raise productivity, allowing cows to fatten faster - making it possible to achieve the same amount of product with fewer cows. India's National Dairy Development Board has estimated that with better feed, the cattle population in India could be reduced from 300 million to 120 million without affecting production. | 
photo courtesy of the
National Cattlemans' Beef Association | However, there are problems. Cows in different parts of the world have different nutritional deficiencies. While some of the nutritional supplements can be administered by a simple nutrient lick, oter types are more awkward to deliver. Some of the new feeds are more costly than regular feed, andwould be a major investment for many of the world's farmers. In some cultures, cattle can be a source of status, cattle dung can be a provider of much-needed fuel, and cattle themselves can be necessary as a protein source - all of which may make efforts to convince farmers worldwide to change their farming habits difficult.
Many cattle producers take great pains to point out that methane is only one of a number of greenhouse gases. In fact, they claim, driving six miles to the store to buy a hamburger has much more of an effect on greenhouse gases than producing the hamburger itself. And the question remains to be seen whether more progress can be made towards curbing greenhouse gas emissions through many small, focused programs, like developing more efficient cows, or through large sweeping programs that may have a more dramatic effect - but may be much more difficult to implement. | Join us as we talk about an innovative way to look at the global warming problem, plus a look at the influence that the ever-growing popularity of sport utility vehicles may be having on the environment.
Guests:
Richard Bowman
Program Director, Global Livestock Producers Program
Appropriate Technology International
Washington, D.C. and Moscow, Idaho
Guy Brasseur
Director, Atmospheric Chemistry Division
National Center for Atmospheric Research
Boulder, CO
Hal Westberg
Professor, Environmental Engineering
Washington State University
Pullman, WA
John German
Senior Technical Advisor, Office of Mobile Sources
Environmental Protection Agency
Ann Arbor, MI
Books/Articles Discussed:
Related Links:
U.S. EPA ruminant
info
A project in monitoring ruminant methane emissions at Texas A&M
CowTown
America
the beasties that produce methane in cows, from the Microbe Zoo
everything dealing with cows, from the NetVet
EPA Office of Mobile
Sources
Contrarian views
from the Coalition for Vehicle Choice
the
official web site for the global climate change conference in Kyoto
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