A Growing Appetite 

World beef production is increasing at a rate of about 1 percent a year, in part because of population growth but also because of greater per capita demand in many countries. Economic analysis shows that if all beef were produced under the economically efficient feedlot, or CAFO (concentrated animal feeding operation), system—which generates fewer greenhouse emissions than many other common husbandry systems do—beef production by 2030 would still release 1.3 billion tons of CO2-equivalent greenhouse gases. If current projections of beef consumption are correct, even under the feedlot production system the buildup of CO2-equivalent greenhouse gases could amount to 26 billion tons in the next 21 years.  
U.N. FAO; U.S. Census Bureau
SOURCE: http://www.scientificamerican.com/slideshow.cfm?id=the-greenhouse-hamburger

Prime Cuts: How Beef Production Leads to Greenhouse Gases 

The largest fraction of the greenhouse effect from beef production comes from the loss of CO2-absorbing trees, grasses and other year-round plant cover on land where the feed crops are grown and harvested. Second most important is the methane given off by animal waste and by the animals themselves as they digest their food. This analysis of the U.S. feedlot beef production system was done by ecological economist Susan Subak, then at the University of East Anglia in England.
SOURCE: http://www.scientificamerican.com/slideshow.cfm?id=the-greenhouse-hamburger


* Livestock was responsible for 51% of global emissions. (Worldwatch Magazine, 2009)

* Methane dissipates from the atmosphere in 12 years vs. 1000 years for CO2.

* Methane global warming potential (GWP) is 68 times that of CO2 after 20 years, 23 times that of CO2 after 100years.

* Over 40% of Black Carbon (BC) emissions are attributed to the burning of forests and savannas.

* When BC lands on ice or snow, it causes rapid melting. A NASA study suggests that BC may be responsible for more than 30% of the most recent warming in the Arctic (i.e., in the last 30 years), contributing to the acceleration of Arctic Sea ice melting. Other ice masses known to be affected by BC deposits are the Himalayas, the Swiss Alps and Antarctica.