What is the lowest-carbon protein? Chicken, for example, has a GHG footprint almost nine times lower than beef's – generating 5.7kg of CO2e per 100g of protein. Alamy Harder cheeses, such as parmesan, are more carbon-intensive than soft cheeses because they are made with more milk Yoghurt, meanwhile, is surprisingly low-carbon, 2.7kg of CO2e per 100g of protein, as not …