The GHG footprint of consuming beef is up to 48 times that of high-protein plants
"The greenhouse gas footprint of consuming ruminant meat is, on average, 19–48 times higher than that of high-protein foods obtained from plants (Fig. 2), when full life cycle analysis including both direct and indirect environmental effects from ‘farm to fork’ for enteric fermentation, manure, feed, fertilizer, processing, transportation and land-use change are considered. Non-ruminant meats such as those from pigs and poultry (and marine fisheries) have a lower carbon equivalent footprint, although they still average 3–10 times greater than high-protein plant foods (Fig. 2).”
William J. Ripple et al., “Ruminants, climate change and climate policy,” Nature Climate Change 4 (2014): 3, doi:10.1038/nclimate2081