Want to slow global warming? Cut back on red meat.

It’s been an interesting month for folks like me who write about farm animals. First, the American Journal of Public Health printed an editorial saying our appetite for chicken nuggets and other meat products can contribute to the spread of diseases like avian flu. (See "Can vegetarianism prevent bird flu?") Then today, The Lancet—likely the most well-respected health journal in the world—published a study declaring that eating less red meat can help curb climate change.

One of the typical ways meat producers try to limit greenhouse gases (especially methane) from cows is by changing feed practices, including feeding animals higher-quality grain or giving them medications that help reduce fermentation in their systems. But according to Dr. John Powles, a public health expert at Cambridge University and one of the authors of the Lancet study, these practices have a “limited impact” on cutting emissions. The only “real option,” says Powles, is reducing demand for meat.

In the industrialized world, consumers eat as much as 90 kilograms of meat per year (or about 230 grams per day)—the equivalent of a side of beef, 50 chickens, and one pig. In the developing world, consumption of animal products is only about 30 kilograms a year, and in Africa, people consume just over 30 grams per day.

According to the study, however, reducing global meat consumption to just 90 grams a day could help cut the methane and nitrous oxide emissions released from cows, and thus help slow the rate of climate change.

Eating less meat can also improve our health by reducing cardiovascular disease and some of the cancers associated with eating high-fat meat products, says Powles. Consumers also have the option of choosing lower-fat, more nutritious, and more humane meat, eggs, and milk from producers who raise their animals outdoors on grass. Because of their lower population numbers and better diets, these farm animals are likely to produce fewer greenhouse gases than the millions of animals crowded together in factory farms. (See "Feeding Livestock Grass: A Climate Solution.")