Changing a light bulb is a better way to prevent global warming than trying to reduce the amount of gas emitted by cows, according to two Cornell University economists.
The effects of cow flatulence on the atmosphere have been greatly exaggerated, Duane Chapman and Thomas Drennen say in a paper to be published in the fall. According to them, the methane emitted by one cow in a year has the same effect on global warming as the fuel burned to power a single 75-watt light bulb."Replacing incandescent light bulbs in industrialized countries with new 18-watt fluorescent bulbs that provide the same amount of light would go much further . . . than trying to regulate bovine emissions," said Chapman, a professor of resource economics.
According to Chapman and Drennen, the carbon dioxide produced by burning fuel and driving cars is a much more serious threat to the atmosphere than methane, a natural gas formed by the decomposition of vegetable matter, and one that can be dealt with more effectively.
Carbon dioxide and methane are greenhouse gases that stop infrared radiation from escaping the atmosphere and are believed to be contributing to the warming of the Earth. The amount of methane in the atmosphere has been increasing by about 1 percent each year, according to Patrick Zimmerman, a scientist at the National Center for Atmospheric Research in Boulder, Colo.
In recent years, researchers have estimated that cows give off as much as 15 percent of the methane released into the atmosphere.
But Chapman and Drennen said those estimates don't take into account the amount of carbon dioxide used up by growing the hay and grains that cattle eat.
Zimmerman, whose research includes measuring the amount of methane emitted by cows, disputed Chapman and Drennen's findings.
"You can't accumulate carbon by growing hay," he said. "It's hard to accumulate much even by growing a forest."
Zimmerman said it is important to learn how much methane is being emitted into the atmosphere from all sources in order to find out why climate conditions are changing so rapidly.
Chapman and Drennen's work is sponsored by grants from the U.S. Department of Agriculture and the Cornell Agricultural Experiment Station.