A scientist in the United States has questioned the impact meat and diary production has on climate change, and accused the United Nations of exaggerating the link.
In 2006, a report published by the U.N. Food and Agriculture Organization (FAO) titled "Livestock's Long Shadow," claimed meat production was responsible for 18 percent of greenhouse gas emissions, which it added was greater than the impact of transport.
Livestock farming already occupies 30 percent of the world's surface and its environmental impact will double by 2050 unless drastic action is taken, the U.N. warned.
Environmentalists and leading campaigners including Paul McCartney, used the findings to urge consumers to eat less meat and save the planet. Last year the former Beatle's much hyped-campaign featured the slogan: "Less meat = less heat."
But Frank Mitloehner, an air quality specialist from the University of California at Davis (UCD), said the U.N. reached its conclusions for the livestock sector by adding up emissions from farm to table, including the gases produced by growing animal feed; animals' digestive emissions; and processing meat and milk into foods.
But its figures for transport did not add up emissions from well to wheel; instead, it considered only emissions from fossil fuels burned while driving.
"This lopsided 'analysis' is a classical apples-and-oranges analogy that truly confused the issue," Mitloehner said on the university's Web site.
Mitloehner also pointed to the fact that leading authorities agree raising animals for food accounts for about 3 percent of all greenhouse gas emissions in the U.S., while transportation creates an estimated 26 percent.