Bloomberg Businessweek reports on how cows and their methane emissions are overlooked in the entire global-warming debate:

Cattle and other ruminants are probably the biggest human-related source of methane, a gas adding to global warming, and climate negotiators have paid too little attention to livestock, a team of researchers said.

Cows, sheep, goats and buffalo produce “copious amounts” of methane in their digestive systems, Oregon State University wrote in an online press release, citing analysis published in the journal Nature Climate Change today. One of the most effective ways to cut the gas would be to reduce the global population of ruminant livestock, the university said.

Ruminants, which ferment plants in a specialized stomach before digestion, are estimated to be the largest single human-related source of methane, with greenhouse-gas emissions from sheep and cattle 19 to 48 times higher than beans or grains per pound of food produced, according to the report.

“Reducing demand for ruminant products could help achieve substantial greenhouse gas reductions in the near-term,” Helmut Haberl of Austria’s Institute of Social Ecology, a study co-author, was cited as saying in the statement. Lowering demand would be “a considerable political challenge,” he said.

The number of ruminant livestock in the world has risen 50 percent in the past 50 years to about 3.6 billion animals, according to the report. About a quarter of the Earth’s land area is used for grazing, mostly cattle, sheep and goats.