A new United Nations report calculates that raising livestock contributes more to global warming than does transportation. Of the greenhouse gas emissions that can be traced to human activities, livestock manure emits 65 percent of global nitrous oxide, and the animals' digestive systems release 37 percent of global methane. Both gases are more damaging than carbon dioxide.
The impacts of livestock are clear in Brazil's Cerrado, a vast tropical savanna that is now a leading global hotspot for cattle production. Over 71 percent of the ecoregion has been converted into pastureland and agricultural fields. The UN report suggests that recognizing the local and environmental tolls of meat and dairy production can help improve livestock industry practices and curb future impacts.