Sheep, like cows, are ruminants and ruminants burp methane, which is a greenhouse gas. Per unit of lamb or beef, about two-three times[1] as much of greenhouse

Sheep, like cows, are ruminants and ruminants burp methane, which is a greenhouse gas. Per unit of lamb or beef, about two-three times[1] as much of greenhouse units ("CO₂ - equivalents") is produced than for pork. Chicken has an even lower carbon footprint. I think it is evident that many in the Western world eat more meat than they need to to stay healthy. The best for your health and the environment is probably to eat an as varied diet as possible, with lots of vegetables to complement your meat/protein intake. [1] numbers differ depending on who you ask, and on which farms were measured.