植物性和動物性食品的生態足跡

陳惟華/愛家自然診所院長、英國牛津大學神經學博士、醫界蔬食聯盟發起人之一

Table 2. The ecological footprints of plants and animal products.

Items	Ecological footprints of plants vs animal products	References
I	Carbon footprint－emission amount of anthropogenic greenhouse gases which cause global warming
	Agriculture＞1/3 of all anthropogenic GHG emissions (Food is the largest source of global GHG emissions)	IPCC AR4
	1.     Petroleum Industry：26%
	2.     Livestock industry：14.5%〜18% (1) Beef production: 41% of livestock sector’s emissions (2) Cattle milk production: 19% of livestock’s emissions (3) Pig meat: 9% (4) Poultry meat & eggs: 8% (5) Other animal products	FAO Reports 2006 & 2013
	3.     Transportation：13%
II	Nitrogen footprint－nitrogen and phosphorus produced by fertilizers & livestock manure, flowing into water to stimulate overgrowth of toxic algae and deplete water oxygen, cause ocean dead zones (eutrophication potential) and produce acid rain.
	1.     Dairy products & Red meat：the highest N2 footprint	Environ Sci Technol, 2010;44 (16): 6450–6456
	2.     Poultry、eggs和fishes：the second one
	3.     vegetables：less N2 footprint
	4.     Grains：the least N2 footprint
III	Food footprint－Livestock consume 58% of the annual crop yields, this over-reliance on crops highlights livestock industry is unsustainable.
	1.     Livestock spent 74% of the world's soybeans and 36% of the grains (enough to feed two billion population), making one billion people starvation & malnutrition.	UNEP Report 2010/6
	2.     16 kg grains fed to cattle produce only 1 kg beef (94% grain loss in weight)
	3.     3 kg plant protein fed to pigs produce only1 kg pork protein （losing 2/3 first-hand protein）
	4.     Resources of a meat-eater consumed can feed 20 people.
IV	Water footprint－Livestock uses nearly 70% of the world's fresh water and it is one of the major causes of water pollution.
	1.     Led to 800 million people living without clean water.	UNEP Report 2010/6
	2.     Producing 1Kg of animal protein requires about 100 times more water than producing 1Kg grain proteins.	Am J Clin Nutr 2003;78: 660s-663S
	3.     Animal protein consumes water 5-10 times more than vegetarian protein.
	4.     Meat production consume lots of water：production of 1lb meat requires 15-time more water than that of 1lb plant protein.
	5.     Huge amounts of livestock manure contaminate river water.
V	Soil footprint－Livestock production occupies 70% of the world's agricultural land.
	1.     Livestock production occupies 38% of the global iceless arable land.	UNEP Report 2010/6
	2.     Land required for meat meals is 10 to 20 times more than that for vegetarian meals.
	3.     Global surface land is overgrazed for nearly 1/3, resulting in over 50% of the surface erosion & degradation.
	4.     Each year 90% of US cropland loses soil at rate 13 times above the sustainable rate of 1 ton/ha/y.	Am J Clin Nutr 2003;78: 660s-663S
	5.     It takes approximately 500 years to replace 25mm (1 in) of lost soil.
VI	Forest footprint－80% of rainforest deforestation is due to livestock pasture and planting forage crops.
	1.     Not only increases 20% of greenhouse gas emission, but also reduces CO2 absorption from trees.	FAO Report 2006
	6.     Eating a ¼lb hamburger meat razes 6 square meters of rainforest and destroys 20 to 30 different species of plants, 20 to 30 different kinds of birds & animals, and 100 different insects.
VII	Energy footprints－The fossil energy required to produce 1Kcal animal protein is more than 11 times greater than that for grain protein production (25 vs 2.2 Kcal).	Am J Clin Nutr 2003;78: 660s-663S
VIII	Disease Footprints	See Table 1