The intensification of farm animal production in industrialized agricultural systems, or factory farms, compromises animal welfare and degrades the environment. Animal agriculture inefficiently consumes natural resources, contributes to deforestation, and produces immense quantities of animal waste, threatening water and air quality and contributing to climate change. The Food and Agriculture Organization (FAO) of the United Nations estimated in 2006 that animal agriculture was responsible for 18% of global, anthropogenic, or human-induced, greenhouse gas emissions and was ―by far the single largest anthropogenic user of land.
Humane Society International, "HSI Fact Sheet: The Impact of Animal Agriculture on the Environment and Climate Change in Brazil" (2010). HSI Fact Sheets: Farm Animal Protection. Paper 2.