Big footprints.

There are surprisingly large hidden costs to hot dogs, burgers, milk, and other animal products, finds a new report entitled Live stock's Long Shadow. Prepared by the United Nations Food and Agricultural Organization in Rome, the report notes that animal agriculture is the second or third biggest contributor to "the most serious environmental problems, at every scale from local to global."

The report's authors calculate that livestock production taps 8 percent of all fresh water used by humanity, primarily to irrigate feed crops. Farmed animals--now 20 percent of the total mass of land animals--are also edging out species and cutting biodiversity. The report observes that 30 percent of the land that these livestock now occupy once nurtured wildlife.

Livestock production is also having a growing influence on climate. Animal farming accounts for 18 percent of greenhouse--gas emissions, making it a bigger contributor than transportation. For instance, livestock are responsible for 9 percent of carbon dioxide releases associated with human activities, mostly as woodlands are burned around the globe for pastures or to create fields to grow feed. Moreover, 37 percent of all human-induced methane comes from livestock. Molecule-for-molecule, this major greenhouse gas contributes 23 times as much to global warming as carbon dioxide does.

The new report was not issued "simply to blame" livestock managers, but to encourage less-damaging practices, says Samuel Jutzi, director of the Food and Agricultural Organization's animal program. Among his group's recommendations: Calculate the cost of goods and services provided to animal agriculture by the environment and pass them along to livestock farmers. Not doing so, the report argues, fosters pollution and overexploitation of resources.--J.R.