Figure 1. Greenhouse gas emissions associated with the production of protein-rich foods. Beef has the highest emissions per kilogram. These emissions data are from Poore & Nemecek (2018), with the exception of  "Ruminant meat," which was calculated based on the amount of beef and lamb consumed in 2022. 

Poore, J. &  T. Nemecek (2018) Reducing food’s environmental impacts through producers and consumers. Science 360, 987–992. https://doi.org/10.1126/science.aaq0216