Fig. 2: Comparison of emissions per calorie of edible fats.

a,b, Shading and contours show grams of CO₂-equivalent GHG emissions per kilocalorie of edible fat produced by conventional agriculture (a) and chemical synthesis (b). Agricultural emissions are shown as the sum of land-use emissions (y axis) and energy-related emissions (x axis), and emissions from synthesis are shown as a function of feedstock emissions intensity (y axis) and energy emissions intensity. Red circles denote specific estimates based on literature and assumed values (as labelled; see Methods). Feedstock emissions include process-related conversion of feedstock to CO₂—for example, during extraction of natural gas, gasification of coal and the eventual human respiration of fossil feedstock (see Supplementary Table 4).