The following is my Philosophical Senior Defense paper, which I wrote for my undergraduate philosopy degree at The University of Minnesota, Morris. It argues that given Hedonic Act Utilitarianism, veganism is obligatory.
Vegetarianism is Obligatory
Jessi Gurr, Spring 2004
Numerous environmental issues deserve ethical scrutiny. Among these issues are fresh water exhaustion, wildlife depletion, and pollution. With a rising world population, these issues are pressing, and we may think of things we ought morally to do in order to prevent them. In this paper, I discuss some of these environmental concerns. I reach conclusions about what we ought to do with regard to these environmental issues from the point of view of the moral theory of utilitarianism.
Hedonic act utilitarianism is concerned with evaluating actions. Roughly, hedonic act utilitarianism states that our obligations consist in making the world as good as we can. To formulate the theory, consider all of the consequences that would result if an act, A, were performed. Call all of these results A’s outcome. For example, suppose that Jane has a date with Jim, but Jane promised Mike that she would help him with his calculus homework before she planned her date with Jim. Jane can cancel her date with Jim, or she can cancel her study session with Mike. Let’s assume that Jane keeps her date with Jim, and examine the outcome of this act. There are different components that make up the outcome â€“ (i) Jane feels some pleasure because she went out with Jim, (ii) Jane may feel some pain because she broke a promise, (iii) Jim feels some pleasure because Jane accompanied him for the evening, and (iv) Mike feels some pain because Jane broke her promise to help him study. The utility of an act, A, is the result of subtracting the total amount of intrinsic badness from the total amount of intrinsic goodness in A’s outcome.
According to the theory of hedonic act utilitarianism John Stuart Mill defends, pleasure is the only intrinsic good, and pain is the only intrinsic bad. Hedonic act utilitarianism states that the utility of an act is determined solely by the amount of pleasure or pain contained in the act’s outcome. So, according to hedonic act utilitarianism, the hedonic utility of A can be determined by subtracting the total amount of pain in its outcome from the total amount of pleasure in its outcome â€“ subtracting the amount of pain that results from (ii) and (iv) from the amount of pleasure that results from (i) and (iii), assuming, for simplicity, that these are the sole constituents of the relevant action’s outcome. Finally, the theory can be stated in this way:
According to hedonic act utilitarianism, an act is obligatory if and only if its hedonic utility is greater than that of any alternative; an act is right if and only if no alternative has a higher hedonic utility than it has; an act is wrong if and only if its hedonic utility is lower than that of some other alternative.
There are many arguments in the literature that suggest that vegetarianism is obligatory given certain versions of Utilitarianism. In general, the bulk of these arguments have focused on pain, suffering, and animal rights. In this paper, I wish to set these common arguments aside and suggest that there are enough other arguments that are sufficient for deeming vegetarianism obligatory, at least in the light of the moral theory of Hedonic Act Utilitarianism. The bulk of this paper is devoted to presenting and examining specific environmental issues. I shall argue that, of the relevant alternatives, vegetarianism maximizes hedonic utility. The term vegetarianism applies to individuals who subsist entirely on a plant-based diet; a person who does not consume animal meats, dairy products, or eggs is a vegetarian. Given facts about the environment that I will present in this paper, I will suggest that the hedonic utility of acts of vegetarianism is greater than that of any other alternative (for example, the acts of consuming meat, dairy, or eggs) and, hence, is obligatory, given act utilitarianism. It is important to keep in mind that we are aiming for the greatest overall hedonic utility, and each individual act performed does count towards that utility. Every time an individual chooses to eat a vegetarian entrÃ©e, her act counts towards the overall hedonic utility in many different ways. She is choosing not to purchase an animal product, which in turn impacts a supplier, a butcher, and others who become aware of her choice. Similarly, every time an individual chooses not to eat a vegetarian entrÃ©e, her act counts towards the overall hedonic utility. She is then choosing to purchase an animal product, support the supplier and butcher, and possibly even influence her friends, children, and others who see her making the choice to eat meat.
Before addressing specific issues, I should note that the argument that vegetarianism maximizes utility is extremely controversial and that there are some obvious exceptions to my argument. There are people, for example, who cannot digest certain kinds of plant sugars, and hence must rely on a diet that is rich in animal products. There are others who live in areas or are in such a financial state that they do not have access to plant foods that would provide them with adequate nutrition. For example, one living in the arctic region may not have access to some plant foods, specifically those plants containing protein, calcium, and certain vitamins. Whether or not one should refrain from eating meat (acting in a life-threatening manner) in such cases depends on what maximizes utility. If, for some people, utility is maximized by sustaining their lives and the only way in which to do this is to eat meat, then by utilitarian principles, they ought to continue to eat meat. A Utilitarian would not insist that one act in a way that is threatening to one’s life (in such cases).
The first environmental concern that I wish to focus on is wildlife depletion. Currently, forests and national parks cover about 34% of Earth’s land. Can the forests and national parks be sustained? The human population has been increasing for the entire history of the species, greatly accelerating since 1850; currently, the population is reaching 6.4 billion. The U.S. Census Bureau predicts that the population will surpass 9 billion in fifty years. Scientists have estimated that the world can support approximately 15 billion people under today’s current conditions. However, this estimation does not assume that 15 billion people can be supported and wildlife areas can be maintained at the same time. People have very basic needs that must be met, and doubling the production of the goods that satisfy these basic needs, such as needs for food, clean water, and shelter, will be a difficult task given that we have only a limited amount of land to work with. David Pimentel, professor of Ecology and Agricultural Science at Cornell University, has done extensive research on current available resources in the world, and his findings indicate that we do not have much room for expansion 1 .
The total land area on the earth, including the poles, can be broken up in the following way:
|Pasture for Meat/Dairy:||24%|
|Unsuitable for crops/pasture:||30%|
Pimentel’s studies confirm that two-thirds of the world’s current land used for agriculture is dedicated solely to raising livestock and producing food for livestock 2 . Imagine a situation in which the world’s human population increases by fifty percent, as is predicted to happen in 50 years. With this increase in population comes an increase in need for food, water, clothing, and shelter. For simplicity’s sake, let’s assume that increases in housing and commercial units do not invade any areas that are currently used for natural parks, forests, or agriculture, that humans simply expand on the current 30% of non-arable land 3 .
A fifty percent increase in population will result in a fifty percent increase in food (and clothing) consumption. Assuming that humans do not change their dietary (and clothing) habits, this means that the current 12% of the world that is being used for food/fiber production will need to be increased to 18% (we can show this using simple algebra; a fifty percent increase means that one-and-a-half times more land will be needed for food/fiber crops, an increase from the current 12% of land dedicated to food/fiber to 18%). In addition, the current 24% of the world that is used as pasture and food production for meat and dairy will need to be increased to 36%. With this increase in agricultural land needed to support the future human population, we can see that the forests and national parks that now make up one-third of Earth’s land will expand over only 16% of the land in the future.
Two-thirds of the world’s crops are being fed to animals so that animals can, in turn, be fed to humans. In fact, about 90% of the grain produced in the United States goes to feed livestock (De Haan, 1998). About half of the land area in the continental US is dedicated to agriculture, and most of that goes toward the production of meat. In order to meet the demand for meat that will significantly increase with an increasing population (assuming no change in diet), animal farm productivity will need to be increased, resulting in an increase of land area that is needed to maintain the production of meat.
Increasing the amount of land that is needed to maintain the production of meat leads to severe depletion of nature reserves, forests, and wildlife areas. Acting in ways that preserve wildlife has a greater hedonic utility than acting in ways that deplete wildlife. First, we need forests in order to survive: trees produce oxygen and the depletion of trees (the depletion of forests) causes an increase in carbon dioxide levels. Increases in carbon dioxide levels have been asserted as one of the leading causes of global warming 4 . Second, people take great pleasure in strolling through nature reserves, taking boating trips, and experiencing wildlife. Depleting wildlife areas for agriculture will decrease such pleasure-generating activities. For example, biologists will have fewer plants and animals to study (which will decrease chances of discovering new drugs for the treatment of severe diseases), living areas will become more crowded as farms take over available land space, many species of animals and plants will be lost as their habitat disappears, and the Boy Scouts will have less camping ground.
There is one way in which we can significantly reduce the amount of land needed for agriculture: adopting a vegetarian diet. Per calorie, one vegetarian meal requires about 1/12 of the land area that is required to produce one hamburger. If the human population were to exclude all animals and animal by-products from its diet, there would be no need for pig farms, chicken factories, cattle and dairy farms, or egg hatcheries. If the United States alone stopped feeding 90% of its grain to livestock, there would be much more available land to grow food for human consumption. There would be plenty of room to expand food/fiber crops if we abolished animal farming, and sufficient space would be available for the population to increase threefold, without destroying any forests or national parks. If we all (special cases aside) adopted a vegetarian diet, we would not need to face all of the negative consequences that come from wildlife depletion. So, it appears that the hedonic utility of vegetarianism is greater than that of the principal alternative; eating meat and meat by-products leads to wildlife depletion and the negative consequences I mentioned earlier. Given hedonic act utilitarianism, vegetarianism, it seems, is obligatory.
My opponent may agree that vegetarianism can account for some increase in hedonic utility, but may question whether or not it actually maximizes hedonic utility. I have not yet considered things that may bring about a loss of utility upon this conversion to vegetarian diets. The rise of vegetarians will bring about a loss of demand for animal farmers, which leads to a decline in animal farms and meat factories. Many people are dependent on animal farming for their livelihood; slaughterers, farmers, livestock veterinarians, meat processors, and others will need to look for alternative sources of income. Many will lose their jobs, and those dependent on the meat business will incur a significant amount of pain. Hence, it seems that becoming vegetarians may actually decrease utility sharply, and by my own utilitarian principles, we ought not to be vegetarians.
In response to this objection, I draw an analogy between jobs in agriculture production and jobs in weapons production. It is true that a decrease in demand for animal products will lead to a decrease in jobs for people who produce animal products. It is also true, however, that if we completely end war and the use of guns, tanks, bombs, etc. then there will be a decrease in jobs for people who produce weapons. I remind the reader that the goal is to maximize utility, and that many farmers do not depend solely on animal products to make their living. In addition, according to Great Britain’s Annual Business Inquiry (in conjunction with the Office for National Statistics), the number of people worldwide employed in agriculture pales in comparison to the number employed by manufacturing and service-oriented jobs. Approximately one percent of Britain’s employees are involved in agricultural careers, and that number only reaches 3 percent world-wide.
What must be considered with this objection is the difference between the hedonic utility that stems from vegetarianism and the hedonic utility that stems from providing agricultural jobs for people. There may be instances where a family simply cannot survive unless its members are involved in animal farming, and a Utilitarian would make an exception for such an instance. However, in general the benefits for phasing out animal farming and adopting a vegetarian diet are far greater, and the utility that can be gained by preserving wildlife, allowing for more medical research on plants, and allowing preserving forests and national parks for our future generations to enjoy will affect more people in the long run than a one-time decrease in the number of jobs in agriculture. Each act of vegetarianism increases utility, which makes it clear that vegetarianism is obligatory. There are many other benefits of vegetarianism I have not yet discussed that will make it clear that the hedonic utility of vegetarianism outweighs the hedonic utility of non-vegetarianism. I will now address other environmental issues that vegetarianism can help alleviate, which will help to show that vegetarianism maximizes hedonic utility. There is a limited source of fresh water in the world. Currently, there are 80 nations in the world experiencing significant water shortages. 82% of fresh water pumped worldwide is consumed (non-recoverably) by agriculture. In the United States, 85% of freshwater is consumed by agriculture, and much more than two-thirds of this is pumped into animal farming (Pimentel 2001, pp. 128-130). As I mentioned before, animals are already consuming two-thirds of the crops produced in the United States, and in addition to the water that is pumped into the crops eaten by livestock, animals must also have drinking water, and massive amounts of water are used in other agricultural processes such as cleaning processes and waste removal.
We are already depleting the water supply in the largest aquifer in the United States, the Ogallala aquifer, 140% faster than the rate needed for fresh water to be restored to the aquifer. Pimentel estimates that if we keep draining the aquifer at this same rate, it will be dry in 40 years (Pimentel 2001, p. 129). An increase in world population will result in an increase in the amount of fresh water required to support it. In addition, fresh water will be needed to be provided to livestock and used to grow the plants that livestock eat. It seems that at this rate, an increased population in the future will have much less fresh water available than we have today.
Humans rely on fresh water for health and sustainability. Certainly preserving fresh water contributes to maximizing utility; if we deplete our water sources too quickly, we will be left with contaminated water that can lead to diseases, pollution, and decreased crop yields. More pleasure will result from a future population with access to fresh water than from a future population with water shortages. Animal farming only accelerates fresh water depletion. It takes about 660 gallons of water to produce one pound of chicken, including the skin and bones. With this same amount of water, farmers could produce enough wheat for 5 pounds of wheat bread or 16 pounds of broccoli. The US poultry operations (chicken and egg-producing) use 96.5 billion gallons of water each year (Lustgarden, 2003). If we get rid of animal farming (which is accountable for at least 50 percent of our current water usage in the United States), more water will be available for human consumption. Pimentel’s studies yield the following data concerning the amount of water that certain agricultural practices require:
|Beef||12,009 gallons/pound 5|
In other words, it takes approximately 200 times more water to produce one pound of beef than it does to produce one pound of potatoes. The United States Drug Administration (USDA) has compared beef to potatoes based on calories. There are 1197.5 calories in one pound of beef, and 288 calories in one pound of potatoes. This means that 4.15 pounds of potatoes provides an equal amount of calories as one pound of beef. It takes approximately 249 gallons of water to produce an equivalent number of potato-calories as 12,009 gallons of water takes to produce the same number of beef-calories. This means that it takes 50 times more water to produce one beef-calorie than it does to produce one potato-calorie.
It seems clear now that we ought to do all that we can to refrain from depleting our fresh water sources, for the hedonic utility of having available fresh water outweighs that of having contaminated water which could lead to sickness. Each vegetarian meal that a person chooses to eat uses less water than each non-vegetarian meal she choose to eat. According to Hedonic Act Utilitarianism and the concerns that I just raised, a person is obligated to make choices that will deplete less fresh water. Choosing to eat vegetarian meals uses less water, and the choice always to eat vegetarian meals leads to less of a demand for animal farming, which in turn leads to less of a demand for fresh water (or greater preservation of fresh water). Hence, according to the utilitarian principle, we ought to be vegetarians because it maximizes hedonic utility. If the preservation of land isn’t enough to convince my opponent that a vegetarian diet maximizes utility, then surely the preservation of water helps make my claim stronger.
My opponent may now interject and suggest that we may be able to come up with a more efficient way to farm animals. Specifically, what if we were to come up with a way to farm animals that doesn’t involve massive amounts of land use and water depletion? For example, what if we came up with some way to produce fifty times as much food on the same land space, and found an extremely efficient and environmentally friendly way of desalinating ocean water for use in animal farming?
I will admit that it is certainly possible that we will come up with a more efficient way to farm â€“ it is possible that we could greatly increase the amount of food that is produced on an acre of land, and we may keep farm animals in conditions and abolish pastureland so that livestock takes up minimal land space. However, I do not think that increased crop yields and restricting living areas for livestock will bring about more utility than adopting vegetarianism. All farm animals must eat in order to survive and produce meat for human consumption. Every animal that eats produces waste. One large egg farm produces approximately 125 tons of manure every day (Bell 1990, p. 26).
Pollution is one of the largest environmental concerns, and the animal farm industry is not helping to decrease worldwide pollution. Environmental contaminants from factory farms include animal waste, dead animals, dust, silage, production water, storm water runoff, animal bedding, contaminated products, machines, chemicals, and wasted fossil fuels (Oltjen 1994, p. 10). While animal waste is sometimes used as fertilizer and can actually benefit the environment by reducing the amount of chemicals that are used in fertilizers, the amount of animal waste that is produced each day is well over the amount that organic farmers could ever use on their crops. In addition, disposal and transportation of animal waste is often times very costly, especially for a large egg farm producing 125 tons each day. In Arkansas, chickens generate as much waste as 8 million peopleâ€“nearly three times Arkansas’ entire population. In 1992, The Washington Post reported that nearly half of the streams in northwestern Arkansas are so polluted with chicken and livestock waste that they are off-limits to swimmers. Bacteria and nitrates found in animal feces have contaminated almost every tributary of the White River, in turn contaminating the drinking water of 300,000 people (Holleman 1992, p. 10). Pollution resulting from dairy farm manure and hog farm manure threatens many places in the United States â€“ the contamination amounts in North Carolina are massive.
I don’t think my opponent will disagree with the view that less pollution results in a higher hedonic utility than more pollution. High levels of pollution bring about high levels of water contamination, and have been shown to increase cancer rates, asthma, and destroy arable land. We ought to do all that we can to prevent pollution. Again, becoming vegetarians will vastly decrease the amount of animal manure that contaminates lakes, rivers, and streams throughout the world; becoming vegetarians will decrease the amount of dust, silage, animal bedding, chemicals, and other pollutants associated with animal farming. These facts about pollution once again support my view that vegetarianism maximizes utility.
There is an economic objection to my argument that I wish to consider. The argument focuses specifically on three countries: Australia, New Zealand, and the United States. These countries rely heavily on their exports, many of which are animals and animal by-products. These are the only countries in the world that are net exporters of food (meaning that they export more food than they import). If the world switches to a vegetarian diet, the economies in these countries may drop significantly because many of their exports will be lost. Troubled economies in these areas will directly affect many of their citizens, bringing about an extreme loss in utility. It may be the case that we ought to keep consuming meat, dairy, and eggs because it is in the best economic interest of these countries.
My reply is that the United States, New Zealand, and Australia would continue to be net exporters of food even after an evolution to a world-wide vegetarian diet. Currently, the United States feeds 2/3 of its cash crops to livestock. What if the US were to export its crops instead of exporting its animals? In addition, there would be less money pumped into animal farming, allowing that money to be spent elsewhere. Such spending would most likely help the economy. There are many underdeveloped countries that cannot afford to buy meat. These three countries could export their crops at a much cheaper cost than the cost at which they export meat, and provide food to those underdeveloped countries. These countries could even export their grain at prices greater than the prices that animal farmers pay for grain.
In Eastern Canada, the economy relied primarily on fish exports. Eventually, however, extensive fishing led to an absence of fish, and the economy fell. If the provinces had invested more into finding alterative exports rather than relying only on fishing, this tragedy may have been avoided. The US, Australia, and New Zealand could face an economic crash if animal farming continues. If animal grazing continues at the current rate, pasturelands will be destroyed and will no longer be arable. Run-off from lagoons will destroy the nutrients in the ground thus causing once arable lands to become barren. The economy is not going to benefit from land that it can’t grow food on because it has been over-grazed or contaminated with chemicals. Working toward a solution to prevent this likely side effect of animal farming will produce more hedonic utility than allowing the land to become barren will.
While there may be some areas that will be affected by a decrease in animal product imports and exports, it is important to consider that only a small percentage of the world’s imports/exports are agricultural. The majority of imports/exports are natural resources and non-agricultural goods. A decline in animal farming may bring about some economical changes in the world, but it is not clear that a decline in animal imports/exports will significantly affect hedonic utility. It is even possible that such a decline would increase utility.
I hope that my opponent is beginning to see the sizable environmental benefits of vegetarianism. I have two more important objections that I wish to consider, neither of which is an environmental concern, but may bear on the amount of hedonic utility associated with vegetarianism. The first is the argument from health, and it can be stated as follows:
A person who consumes no meat, dairy, or eggs is missing out on important nutrients such as calcium, protein, and vitamins found in animal-based foods. The lack of these nutrients leads to improper muscle development, bone deficiency and osteoporosis, and numerous other health problems. Clearly, eating foods that possess these nutrients contributes to better health and hence increases utility. As the main focus should be maximizing hedonic utility, one should focus on health issues before environmental issues. For if the human population lacks good health, then solving environmental issues will fall second to solving health issues. It then follows that we ought not to be vegetarians.
This is a very common objection to vegetarianism â€“ one that I have heard from many close friends and family members. While I commend them for their concerns regarding health, their argument is flawed. I’ll grant that if the only way for people to obtain the nutrients necessary for maintaining health is by consuming animal products, then it follows that we certainly ought to eat animal products. The error, of course, is in the assumption that humans cannot gain necessary nutrients from a strictly plant-based diet.
Contrary to popular belief, an entirely plant-based diet can provide all of the nutrients necessary to live a healthy life. In addition, a plant-based diet is one hundred percent cholesterol free, and actually helps to prevent many diet-related illnesses. I will admit that there are some people who have an intolerance to certain sugars found in plants, and that there are people who live in areas where it is extremely difficult, or even impossible, to obtain the necessary nutrients in food to lead a healthy lifestyle. The Utilitarian principle would not insist that these people jeopardize their health for vegetarianism, but many people in the world do have access to vegetarian foods that provide sufficient nutrients. My argument is meant to convince all who can feasibly be vegetarians to adopt a vegetarian lifestyle, not to insist that people become vegetarians if it would jeopardize their health.
Consuming sufficient protein and calcium are the two greatest concerns to those opposed to a vegetarian diet for health reasons. I do not wish to go into details about the amounts of protein and calcium the human body actually needs (and the negative side effects of animal-based protein and calcium), but I would like to point out that these nutrients can be obtained from other sources. Protein is found in nuts, soybeans, beans and legumes, grains, and sprouted seeds. Essential amino acids are found in apples, alfalfa, carrots, beets, spinach, avocados, olives, and numerous other sources. Calcium can be found in oatmeal, soybeans, almonds and other nuts, spinach, broccoli, and any green leafy vegetable. Other vitamins and minerals that may be of concern can be found in plant sources as well.
It is incorrect to claim that proper nutrition cannot be obtained from a vegetarian diet. Additionally, vegetarian diets have been shown to offer a wide range of health benefits. Recent research has shown that heart disease, obesity, diabetes, cancer, osteoporosis, kidney stones, and many other health problems are less frequent in vegetarians than they are in meat eaters. The diet choice that offers maximum benefit to an individual is a vegetarian one.
The final objection that I would like to address is the objection from taste. Some people simply like the way that meat tastes, and say they eat meat and animal products simply because â€œthey taste good.â€ My opponent may argue that, putting all environmental, health, and economic factors aside, the satisfaction of one’s taste buds is reason enough to eat meat. He will argue that such a drastic change in diet will leave a void in the mouths of many people, and that taking meat away from so many people will result in a loss of utility, which does not make vegetarianism obligatory.
Perhaps my opponent hasn’t been exposed to vegetarian cuisine. â€œIt doesn’t taste the same,â€ he will argue â€“ and I agree that it doesn’t. But something need not taste bad just because it has a different flavor from what one is used to. In addition, people who are not raised on a meat-eating diet are not likely to enjoy eating meat; if they are not accustomed to eating it, they don’t even miss it. The â€œlongingâ€ and â€œcravingsâ€ that may be associated with eliminating meat from one’s diet will likely go away as wellâ€“in my case, they never even existed. There hasn’t been a day in the last ten years that I have craved meat. I haven’t craved milk, cheese, or eggs in a long time, and have no desire or â€œlongingâ€ to eat them.
I would like my opponent to examine the other factors that I have presented in this paper that suggest that an increase in utility arises from vegetarianism. It seems foolish to claim that the utility gained from concerns of taste surpasses the utility gained from environmental benefits, economical benefits, and health benefits. If one is still convinced that the utility gained from tasting meat outweighs the utility gained from being a vegetarian, there are many meat, dairy, and egg substitutes and soy products on the market that taste very similar to the non-vegetarian alternative.
It is important to note that vegetarianism is still a controversial issue, and though it may not be possible (for health or feasibility reasons) for all people to become vegetarians, many people in this world have access to vegetarian cuisine and still continue to consume animal products. I have presented three arguments to support the view that vegetarianism maximizes hedonic utility because it brings about positive changes in the environment. I have considered three major environmental issues: wildlife depletion, fresh water shortages, and pollution, and concluded that adopting a vegetarian diet brings about maximal utility and aids in solving these three crucial environmental problems. I have also considered economic objections to vegetarianism, and I do not think that vegetarianism will negatively impact the world’s economy. Finally, I considered health objections and taste objections to vegetarianism, and concluded that these objections are flawed. Taking environmental concerns into consideration, it seems clear that vegetarianism maximizes hedonic utility. From this, we can conclude that vegetarianism is not only right but obligatory, at least, if utilitarianism is true.
1 The following information is taken from Pimentel’s studies, revealed in Ecological Integrity: Integrating Environment, Conservation and Health. pp. 121-136.
2 This figure agrees with similar statistics reported in Livestock and the Environment: Finding a Balance.
3 Note that if I were to assume that people began using current forest and wildlife areas for living areas and commercial establishments, this would add to the decrease of forest and wildlife areas and would not hinder my argument; it would actually help it.
4 Another significant gas that contributes to the greenhouse effect (global warming) is methane. Today, cattle are among the leading producers of methane. A decrease in the number of cattle that are commercially produced will lead to a decrease in the amount of methane in the air.
5 Data from Pimentel (2001), pp. 132-134. Note that the figure for beef is assuming an average two-year lifespan for farmed cows. However, most dairy cows live for 4-5 years, and range cattle often live for 5-6 years.