Eating meat is common in many parts of the world. Livestock's Long Shadow is a report prepared by the UN that documents the impact of livestock on the environment. How are the two related? Meat production, for lack of a better term, is a major source of GHG and the demand for meat increases GHG and, by extension, global warming.
The Globe and Mail summarizes it nicely in Ignoring the meat of the global warming issue. I realize not everyone wants to or can stop eating meat but it has been advocated as a way to reduce your "carbon footprint". Reducing meat consumption could help along with buying local meat products where possible. The Globe article really puts it into perspective. With BBQ season in full swing I'm sure it will be tough for many people but try nonetheless.