We continue to beef up big time.

• Position: Your Life

Global meat production and consumption have increased rapidly in recent decades, with harmful effects on the environment and public health as well as on the economy, according to the Worldwatch Institute's Nourishing the Planet project, Washington, D.C. Worldwide meat production has tripled over the last four decades--and is up 20% in just the last 10 years. Industrial nations are consuming nearly double the quantity of developing countries.

"Much of the vigorous growth in meat production is due to the rise of industrial animal agriculture, or factory farming," points out Danielle Nierenberg, director of Nourishing the Planet. "Factory farms pollute the environment through the heavy use of inputs such as pesticides, herbicides, and fertilizers utilized for feed production."

Large-scale meat production also has serious implications for the world's climate. Animal waste releases methane and nitrous oxide, greenhouse gases that are 25 and 300 times more potent than carbon dioxide, respectively. "The world's supersized appetite for meat is among the biggest reasons greenhouse gas emissions are still growing rapidly," warns Robert Engelman, president of Worldwatch.

"Yet, properly managed and scaled meat production--like the kind pursued by small-scale pastoralists on dry grasslands--could actually sequester carbon dioxide. It's largely a matter of rethinking meat at both ends of the production-consumption trail."

Dirty, crowded conditions on factory farms can propagate sickness and disease among the animals, including swine influenza (H1N1), avian influenza (H5N1), foot-and-mouth disease, and mad-cow disease (bovine spongiform encephalopathy). These diseases not only translate into enormous economic losses each year--the United Kingdom alone spent about $25,000,000,000 in a three-year period to combat foot-and-mouth disease--they lead to human infections.

Mass quantities of antibiotics are used on livestock to reduce the impact of disease, contributing to antibiotic resistance in animals and humans alike. Worldwide, 80% of all antibiotics sold in 2009 were used on livestock and poultry, compared to 20% for human illnesses. Antibiotics that are present in animal waste leach into the environment and contaminate water and food crops, posing a serious threat to public health.

The amount of meat in people's diets has an impact on human health. Eaten in moderation, meat is a good source of protein as well as important vitamins and nutrients such as...