Here's another reason to go vegetarian or at least eat more vegetarian meals:
According to a report from the Food and Agriculture Organization, farmed animals are a top contributor to today’s serious environmental problems. The report found that livestock produced 35 percent to 40 percent of all methane emissions (which have 23 times the global warming potential of carbon dioxide), 65 percent of nitrous oxide (which is 320 times as warming as carbon dioxide), and 64 percent of ammonia, which contributes to acid rain. In addition to climate changes, the growth of global meat production adds immensely to water pollution and the reduction of forests for livestock grazing. Nearly 30 percent of the Earth’s entire land surface is used for grazing animals, and that amount is expected to grow because the global livestock sector is growing faster than any other agricultural sub-sector.
Steinfeld H, De Haan C, Blackburn H. Livestock-Environment interactions: Issues and options. Food and Agriculture Organization of the United Nations, the United States Agency for International Development and the World Bank. 2006. Available at: http://www.fao.org/docrep/x5305e/x5305e00.htm# Accessed: Dec. 4, 2006.
Source: Physicians Committee for Responsible Medicine