It is scientifically well established that in general, fewer resources are required for the production of plant-based foods than animalbased ones. For example, a given amount of grain, if used to fatten a chicken for slaughter, will yield only about one fifth its weight in edible protein as if consumed by humans directly; if for a pig, one tenth; and if for a cow, less than one twentieth. In general, plant agriculture is less ecologically taxing than animal agriculture, and the negative impact of many edible crops is aggravated by the fact that a majority of wheat, soy, and corn grown in many regions is used to feed animal livestock rather than humans directly. That said, different crops and methods of production still vary widely in terms of sustainability.

One of the most ecologically destructive crops is palm oil, whose production frequently involves the clearing of tropical forests rich in biodiversity. In Indonesia, palm oil deforestation has proven especially destructive due to the use of fire in forest clearing, which ignites peat deposits in the soil and can spread rapidly and uncontrollably over vast areas. In September and October 2015, carbon dioxide emissions from forest fires in Indonesia sometimes exceeded the average daily emissions from all U.S. industry combined. On a more local level, palm oil deforestation imperils species including endangered orangutans, elephants, tree kangaroos, and other species less widely known but equally important to the health of their ecosystems.