I have been starting to hear this argument too much, so I thought I would tackle it, and see if it really holds up. So let me know what you guys think, any critique is welcomed (if you want me to do other upper and lower estimates in other places let me know too). I just wrote this up having done the calculations so im sure there are some silly flaws, maybe some big ones.
The locavore argument (at least the one i am talking about) is that a society which eats only grass-fed large herbivores (cows) is actually more ethical and environmentally sustainable than veganism.
As far as ethics are concerned this principle was proposed by Davis (an enemy of Peter Singer) and has several major flaws, which if addressed and are run through his back of the envelope math, come out with numbers in favor of vegetarianism [1,2]. So I think ethics are taken care of. Thus I want to talk about efficiency (land specifically).
Some starting facts:
- Acres of Pastureland in US: 410,000,000 (rounding up) [3]
- Acres of Rural Land: 51,000,000,000 [3]
- Cows killed per day in the US: 100,000
- Acres needed per cow: 2-10 [various undisputed sources, though i could pull some up]
- It takes 2 years to grow a cow before they are killed.
For each day of meat we would need 500,000 acres on average for 2 years time (in other words every day of meat takes up 500,000 acres for 730 or so days).
Also we have to consider the land needed for alfalfa stockpiling for winter months. Say that this is about 2 months of the year. The cows will need 40 pounds of hay per day. So for 2 years, that is 2 months of hay feeding. So 120(days)*40(lbs)*100,000(cows)= 480,000,000 lbs of hay.
There are about 14,000 lbs. of hay created per acre per year [4]. Over 2 years 28,000 acres are made. 480,000,000/28,000=17,000 acres needed in addition to the half million.
This means each "day" of meat requires 517,000 acres of land. This is required for 730 days. 517,000*730= 377,410,000 acres of land.
Already this is 92% of the pasture land in the US. Presumably, a fair amount of this is actually IN USE, so we would need to cut down trees, convert croplands etc (so much for the environmental argument). Unfortunately there is not much data on how much land is in use vs unused land. But the next calculation definitely shows that it doesn't really matter.
Beef consumption is WAY down in the united states so were is the rest of the meat from? Mostly chicken.
So lets say… since most locavore arguments agree that large factory farms are terribly unethical (one thing we agree on) that we convert totally to grass fed beef, then eating the same amount of meat (or more if we are all paleo), means converting from chicken meat to cow meat.
Let us recalculate. 8,000,000,000 chickens are killed for food a year (in the US). Most chickens are 4-5 pounds and about 62% become meat. So that means about 2.5 pounds of meat per chicken. This is 20,000,000,000 pounds of meat. Even if only 1.5 pounds came from a chicken, that is 12,000,000,000 pounds. Since most cattle "yield" 600 pounds of meat. So that means 20,000,000 to 34,000,000 more cows.
Acres for upper estimate: 34,000,000*5=170,000,000
Acres for lower estimate: 20,000,000*5=100,000,000
Hay calculations for upper estimate: 34,000,000*40*180= 244,800,000,000 pounds of hay and thus 8,700,000 acres
Hay calculations for lower estimate: 20,000,000*40*180=144,000,000,000 pounds thus 5,000,000 acres.
So either 178,700,000 acres or 105,000,000 acres. Per day.
So multiplying by 730 days. That is 130,451,000,000 acres or 76,650,000,000 acres.
According to the ERS there are only 51,000,000,000 acres in the rural US [3]. Both numbers even the low end are significantly higher than this. And both are MUCH higher than the current amount of pasture lands.
Without even adding the numbers in the early calculation, or pigs, and any other meat, this simply cannot be done, especially as the population grows. Even under the locavore scheme, drastic reduction of meat products would be necessary, and plant based diets not only win out ethically [1,2] but are still the most efficient in terms of environmental sustainability. If we are truly trying to move towards an ethically sound and environmentally sustainable food system we can only look towards plant based diets.
[1] http://www.jgmatheny.org/matheny%202003.pdf
[2]http://animalrights.aresistance.net/...ing%20Beef.pdf
[3]http://www.ers.usda.gov/statefacts/US.htm
[4]http://www.uaex.edu/Other_Areas/publ...F/FSA-2005.pdf
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