August 1, 2013 — Global crop yields are not growing fast enough to meet the demands of a population that will reach 9 billion by 2050. This is the finding of a recent study published by Deepak Ray at the University of Minnesota’s Institute on the Environment (where I am a graduate research assistant), which is in response to previous studies estimating that crop production will need to double by 2050 in order to meet growing food demands. But if global population (currently at 7 billion) is expected to increase by 2 or 3 billion by 2050 — a 30 to 40 percent increase — why would crop yields need to double? Where is the extra demand coming from?
The main culprit is increasing meat consumption. As people move out of poverty and get wealthier, they consume more meat and dairy.
China, for example, has seen a rapid shift to the middle class in the past 20 years. In 1989 China produced about the same amount of meat as the United States, but now China’s meat production is almost twice the production in the U.S. Because meat-heavy diets require substantially more crops to produce than plant-based diets (it takes about 20–30 calories of feed to produce just one calorie of edible beef, for example, and 6–9 calories of feed to produce one calorie of chicken), growing global wealth has surpassed population growth as the bigger reason for increased crop demand. As higher proportions of crops go to animals first, people are only indirectly and inefficiently fed. On average, of every 100 calories we feed to animals we only get about 12 back in the form of meat and dairy. How many people could we feed with those calories if we eliminated that loss?
My colleagues and I set out to answer this question and found some surprising results, published recently in the journal Environmental Research Letters. Globally, 36 percent of all calories produced on croplands never become food for human consumption, but are instead used for animal feed. Differences by country are stark: In India less than 10 percent of crop calories are fed to animals; in China, it’s one-third; and in the U.S., 67 percent. (A bit more of the calories grown on global croplands are directed to biofuels, meaning that more than 40 percent of all the calories we grow never become food.)
If we used U.S. croplands to grow only crops for direct human consumption, we could feed more than 1.5 billion people. That means the U.S. alone could feed a staggering 1 billion more people on the calories that do not end up in the food system.
With all of the land, resources and investments that go into the U.S. agricultural system, my colleagues and I wondered: How many people could we feed with the calories we produce in the U.S. (if all were used for food), and how many people do we actually end up feeding with these investments?
Factoring in the 67 percent we use as animal feed, the conversion rate to meat and dairy, and the crops used for corn ethanol, the U.S. currently feeds only 524 million people (assuming a 2,700 calorie-per-day diet). Great Britain, Italy, Colombia, Ghana, India and Pakistan are among the 69 countries that feed more people per hectare of cropland. While these countries may not have higher yields than the U.S., they direct more of what they grow to people and are therefore able to feed more people per land area than the U.S.
If we used U.S. croplands to grow only crops for direct human consumption, we could feed more than 1.5 billion people. That means the U.S. alone could feed a staggering 1 billion more people on the calories that do not end up in the food system. When we look at a global scale, if we redirected all of the calories being used for animal feed and biofuels to direct human consumption, we could increase calorie availability by 70 percent, enough calories to feed an additional 4 billion people. But this would require us to drastically reduce meat and dairy products to those from only grass-fed or wild-caught animals. Also, the production of biofuels from human-edible crops would need to completely halt.
Those are pretty lofty and unrealistic goals. So we also investigated how less drastic changes could increase food availability. Because different kinds of livestock use feed at different levels of efficiency, switching from grain-fed beef to chicken and pork could allow us to produce more meat with the same feed crops. We found that if globally we chose to eat chicken or pork instead of grain-fed beef, there would be enough additional meat calories to feed 357 million more people. Or, if we directed all feed calories to the production of milk, eggs and cheese instead of meat, there would be enough additional calories to feed more than 800 million more people. This makes it clear that even small changes in diet can increase calorie availability.
Moving away from meat, or from beef to other products, would have ancillary benefits as well. Ruminants such as cattle and sheep have digestive systems that produce methane gas — a serious greenhouse gas with 25 times the warming potential of carbon dioxide over a 100-year period. If we ate chicken or pork instead of beef, we could reduce diet-related greenhouse gas emissions by more than 40 percent.
If the entire global population shifted to a meat-heavy diet tomorrow, we would need twice the amount of cropland currently under cultivation. Most cropland expansion in the 1980s and 90s came at the expense of diverse tropical rainforests in the form of deforestation. Given that global population is increasing and diets are changing, the number of people fed per cropland hectare must increase in order to meet the challenges of food security and prevent further deforestation. Luckily, as this research shows, even small changes in diets — ones that don’t even require us to completely give up things we love, like cheese — can increase the number of people we can feed on existing croplands. 
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We find that feed crops are fed to beef cattle, we get 3 - 5% of those calories back, which translates to ~30 - 20 calories required per calorie beef carcass produced. For chickens it is ~11 - 15% conversion efficiency, which translates to 9 - 6 calories required per calorie produced. These results with citations are shown in Table S6 of the above pdf.
http://journals.ametsoc.org/doi/pdf/10.1175/EI167.1
The second issue is the edible uses for corn. According to the USDA, after biofuels, animal feed, and exports, the next largest percentage of the 2011 corn crop went to producing HFCS (4%). Another 5% went to making a combination of glucose, dextrose, food starch, and alcohol. Only 2% went to "cereals, other", which was mainly corn oil. Diverting corn away from animal feed may provide more calories, but if it only results in more HFCS and corn oil, we haven't really produced more food.
It seems like the main problem with corn is that it is simply not a good crop for producing real food. What could we produce instead of corn that would increase the amount of food, not just calories?
For me, this was a gut wrenchingly agonizing process of sleepless nights and loss, and mourning. I kid you not. The process I went through doesn't make me enlightened, and I certainly don't have all the answers, but I feel like I understand what questions to ask. This article does not get close to asking the correct questions. Why, you ask?
So, let's start by analyzing the basic assumptions of the article (and most of our culture).
1) Human beings are not bound by the same laws of nature as those that govern other species.
2) All livestock for meat consumption must be fed grains in CAFOs that are grown in monocrop fields under intensive cultivation.
3) All cows emit excessive amounts of methane no matter what their diet consists of.
4) All calories are equal.
5) All the products of intensive monoculture are sufficient food for humans.
6) A centralized, commodity-based approach to our food system is the only way to ensure that we all get fed.
Let me explain how I feel looking at these assumptions through the lens of what I feel is the newly forming paradigm will radically shift our thinking about this, and most any other issues.
1) Biologists, in analyzing a population of deer that is booming, would explain it by pointing out that there is either an over-abundance of food or a lack of predators, or a combination of both. Why can't we apply this basic notion of population dynamics to humans? We are animals. We evolved on this planet. We did so within the context of various ecosystems. In short, we are native to this planet and we are a member of the community of life here. The ramifications of applying the laws of nature to humans seems wrought with political and moral hazards. But if you really take the time to think about it, the result would likely be less suffering, not more. Again, our understanding of population dynamics in a biological context would bear this out. Stable populations of a given species are subject to better "quality of life" than their counterpart populations that undergo boom and bust cycles. Why are we different? Do you seriously think we are clever enough to avoid the bust? Seriously?
2) We feed our livestock foods that they did not evolve to eat. Cows did not evolve to eat corn or soy. They evolved to primarily eat grass and other green leafy plants. Neither were chickens supposed to eat exclusively grains. I cringe when I see the egg cartons stating, "vegetarian fed hens," as though I should be glad to eat the egg of a malnourished chicken. Chickens are omnivores. They eat lots of insects and even small critters like mice and voles. What if we began to feed our livestock the foods they evolved to eat? What if we placed them in environments where their food grows without much human intervention? What if they harvested their own food? Could it be possible?
3) I guarantee that if you ate a diet of exclusively moldy and chemically saturated corn and soy, broken up candy chunks, rancid vegetable oils, and other by-products and cast-offs from our industrial food system, along with heavy doses of antibiotics and other medications, you would have a horrendous case of flatulence also. Probably diarrhea too. Cows that are fed living grasses on pasture, not dry baled grasses in barns, with proper grazing management actually sequester carbon and build soils. They are still flatulent, but not excessively so. The evidence for this is in any prairie system in the world that has not been mutilated by thoughtless human intervention. Thoughtful human intervention, like that of the plains tribes of North America, that are in alignment with the laws of nature would be a regenerative factor, not detrimental. The same is true of any animal we keep as livestock. Chickens and pigs are actually forest animals. Forest systems are better for having these species in them, as long as they are managed properly. What if we listened to the animals that are in our care to find out under what conditions they evolved to thrive?
4) All calories do not yield the same results in the context of human nutrition. I understand that reductionist science requires that we come up with some sort of variable that stands as a proxy for baseline human nutrition. The problem becomes when we believe our own proxy to be the only measure. As they say, "what gets measured, get treasured." Quoting the article, "...if we redirected all of the calories being used for animal feed and biofuels to direct human consumption, we could increase calorie availability by 70 percent, enough calories to feed an additional 4 billion people." Perhaps, but they would all become obese diabetics with cancer and heart disease. What if we seriously studied what nutrient quantities and qualities constitutes a diet for the thriving of the human organism free of political and market bias? What if we measured the nutrient density of our carrots? What if we discovered that a happy and properly fed animal resulted in a better nutritional product for human food? How then would we measure "agricultural output?"
5) I realize that this may sound completely elitist, but I no longer regard corn as food. Period. When the vast majority of corn grown on the planet is a GMO saturated many times throughout its life cycle with poisons, and the rest of the corn in the world tests positive for GMO dna, even though it may be grown thousands of miles away from the nearest GMO field. It's no longer food. As far as I'm concerned, if we are gonna grow it, we might as well convert it to fuels, cause I'm not eating it and I don't want it fed to any animal that I am going to eat. If I or my family were starving would I change my tune? Yes. Without a doubt. No question. But as individuals, families, and communities, we have the power, authority, and ability (obligation?) to make sure that our neighbors don't starve and aren't forced to eat and an industrially mutilated excuse for nutrition. What if we cared about the quality of the food that we produced, sold and consumed? What if we decided that it is a bad idea to poison our children?
6) Again, this point of view is usually characterized as elitist, naive or both, but locally grown food from small family owned farms is how the majority of the world feeds itself. We usually disparagingly call it "subsistence farming." Recent statistics from Russia show that the small rural vacation land-holdings that are popular among the Russian rich and middle class produced something on the order of 30-40% of that countries agricultural output. Did they measure in calories? I don't know. But the point is that we don't need huge agribusiness-GMO-monocrop-poison-rancid-food-like-substances to feed the world. What if we took direct responsibility for the food we put in our mouths, instead of hiding behind the "necessity" of colonialist corporate power and government policy and subsidy?
So, from my point of view - from my paradigm - this article, and most of what passes for sustainability journalism is MEANINGLESS except to illustrate just how stuck we are in the status quo while purporting to lead the way to the future. We will not have a future if we achieve Ensia's brand of "sustainability." We will be dead.
You make a good point regarding beef cattle grazing, but this study only investigated how crops with potentially human-edible calories were converted to animal products. Non-human-edible grasses, forages and pasture lands were not included in this study, as made explicit in the paper.
According to the corn grower's association, more corn produced in the U.S. is fed to beef cattle than any other livestock species. Our study investigates, when we feed corn, soy etc. to cattle, how many calories do we get back in the form of human-edible meat? We did account for and make explicit that these conversions are not for forage crops and grasses, they are based on USDA feed conversions for beef cattle on feed, not during their grass-fed or weaning stages.
Feel free to contact me, with any further questions: cass0131@umn.edu.
You make some very excellent points. We use most corn produced in the U.S. for non-food products.
In our study we illustrate how many people we *could* feed on existing croplands, if we shifted crops to all human food. The mix of crops produced in areas that produce a lot of field corn would have to change dramatically. But we illustrate there's a lot of hidden potential in current croplands. Perhaps instead of corn we could produce more soy, lentils, or wheat? There's a lot of social and economic barriers to such a change, but our study illustrates feeding more people with current croplands is biophysically possible.
Feel free to contact me, with any further questions: cass0131@umn.edu.
We also investigated plant proteins in this study and find similar results for protein as well.
The referenced study illustrates the potential of current croplands to feed more people, but we would have to switch from unpalatable field corn to other more palatable and nutritious crops, as we state in the discussion of the article linked:
http://iopscience.iop.org/1748-9326/8/3/034015
Do you have a citation for your point #3? Would love to learn more about that.
Thank you for your response. My beef (ahem...) is not so much with your piece as it is with the editorial position of Ensia. My point is that Ensia's editorial choices do not foster a dialogue that will lead us to a better world. The pieces published here largely are just business-as-usual with a sprinkle of "green" mixed in. The assumptions upon which your piece are based are reflection of our culture and are not any different than the assumptions underlying pretty much all of Ensia's editorial choices. Our culture is not and will never be sustainable.
But since you want to engage on some of the examples I gave, I'll bite. But you probably won't be satisfied with my responses.
I'm not sure what you mean by your statement about plant proteins. Are you trying to equate plant protein with animal protein. Again, we would have to reconcile the need for scientists to have some sort of measurable and comparable number with the fact that, nutritionally, plant protein is not the same as animal protein. Plant protein is missing at least one essential amino acid, carnitine. And it is typically not paired with saturated fats (but that is a whole different debate, don't get me started...) Or if there is carnitine in some plants, you would have to eat huge quantities to get the equivalent amounts found in meat. At that point you might suffer some toxic effects from plant anti-nutrients such as phytates, or at least feel really sick and vomit. If you are talking about soy, well, soy never was food. Historically in cultures where it was grown, it was only used as animal food when nothing else was available, and human food under starvation conditions. The only acceptable way to eat soy is as tempeh or natto, where the fermentation process neutralizes the anti-nutrients sufficiently for it to actually provide nutrition to people. I don't eat soy. I hope you don't either. It's not food. Add the GMO's and toxic sludge, and... just forget it.
Even the more palatable forms of corn you refer to are still not food, in my eyes. The genetics are still contaminated with GMO's and the infrastructure and knowledge base to grow it still would have to rely on massive inputs of poisons. No thanks. I don't eat corn.
I don't have a specific reference for the example I gave in my 3rd point. Frankly, I thought I phrased it in such a way that common sense would not require a scientific publication to prove that it is true. The fact is that there once were massive prairie systems in North America and other places around the world. These systems included large herds of herbivores who were predated upon by apex carnivores, such as lions and tigers and people. The prairie soils used to have massive quantities of carbon sequestered in them. The pioneers of North America took care of that with their 40 acres, a mule, and a plow. My point is, you don't need a scientific study to tell you that this was true. Even after the introduction of the horse to North America by the Spanish, the abundance of the prairies didn't change. The Plains tribes of Native America adopted the use of the horse and became nomadic hunters of bison and the prairie system remained intact for at least a couple hundred years until settlers with plows came along. Is empiricism completely dead? Do you really need a study about cow flatulence? Properly functioning prairie systems sequester carbon. Can you refute that?
If you are truly interested in learning how our current issues with livestock can be turned around and be regenerative rather than extractive, I invite you to research "carbon farming," Joel Salatin, Allan Savory, John D. Liu, permaculture, and biochar. Most of this work is currently not scientific in nature. It is just people doing good work on the land. In fact, it would probably be pretty hard for scientists to evaluate most of the work cited above because the systems that these people are implementing require active observation and active, daily participation rather than data, schedules, and passive management plans. But, again, empirically it is difficult to deny that the techniques and systems developed by the people I reference above are regenerative.
That's what I would like Ensia to wake up to. Sustainability needs to die. Long live regeneration. I'm sorry if it seems like I was bashing your work to make my point about Ensia's editorial choices. I feel kinda bad about that, but I'm really trying to challenge the underlying cultural assumptions, not so much your work. I hope you don't take it too personally.
I was not trying to equate plant and animal proteins, they are different. Although there are many publications, some of which we cited in the referenced paper, that find that combining various sources of plant proteins can provide all essential amino acids. Also many publications have found a vegetarian diet can have positive health outcomes.
The American Dietetic Association has this to say about vegetarian diets:
"It is the position of the American Dietetic Association that appropriately planned vegetarian diets, including total vegetarian or vegan diets, are healthful, nutritionally adequate, and may provide health benefits in the prevention and treatment of certain diseases."
citation: http://dx.doi.org/10.1016/j.jada.2009.05.027
The point of my research, however, is not to tell people what to eat. As a scientist, I aim to describe the impacts of certain practices, with the caveat that no description will ever be perfect.
With regard to managed grazing systems and the work of Savory and others, they have interesting ideas. It would be great to see numbers behind these practices, even if it takes some time for the empirical research.
I definitely don't take scientific disagreements personally. It seems like you have some philosophical concerns with this magazine.
If you'd like to continue chatting about food and grazing systems, my e-mail is cass0131@umn.edu.
You really should check out Joel Salatin's work on rotational grazing, with chicken, cows and pigs, and also Alan Savory who is using the same principles of rotational grazing to literally "green the desert". I am not sure if there is any peer reviewed studies on this, it's not the kind of research BIG AGRO like Monsanto excel in funding.
Rotational grazing can turn arid land, not suitable for growing human food, into lush green landscapes, capable of holding on to the rain which falls on occasion, while pulling out CO2 from the atmosphere and into plants and trees WHILE providing grass fed meat for human consumption. What's not to like about this concept, working _with_ nature? (Except if you are against eating animals, but that's another discussion)
I agree that the work Savory and others are doing is exciting, but there's no evidence for it yet.
What's to stop anyone from making radical claims about the way land ought to be managed that have no physical backing? Empirical scientific research that can be replicated. We have to make decisions based on evidence, and the evidence I rely is empirical and peer-reviewed. If the evidence others are satisfied with is a convincing TED talk, that's their prerogative.
One of the major scientific claims Savory makes (directly in his TED talk) is that holistic management results in a net carbon sink. That is, more carbon is sequestered with his management scheme than emitted. This claim unfortunately has not been validated. This is not to say that holistic management or rotational grazing doesn't create income and promote the productivity of grasslands, it may do these things (many of the links in that pdf discuss these things). However, when ruminants consume carbon they turn it into a powerful greenhouse gas (methane), so we have to include the global warming potential of greenhouse gas emissions when determining whether holistic management can result in a net carbon sink or source.
1) If meat consumption and food wastage are reduced, thereby making more calories available to people, what does that do to population growth? I realize that current food scarcity/distribution issues complicate the answer to this question.
2) Is it the case that as countries industrialize and their rates of population growth consequently decrease, their rates of meat consumption increase, thereby making growth in calorie consumption a relatively constant rate? I suppose you are arguing that rising meat consumption increases calorie demand faster than population growth, but it seems like that is a bit of a counter-factual argument laden with economic and cultural variables. In absolute terms, yes, I understand that meat consumption requires more caloric inputs than non-meat consumption, but there are a lot of related issues here.
For background on the income / calorie demand relationship, it's helpful to read Dave Tilman's recent paper on income and calorie demands (http://www.pnas.org/content/108/50/20260.full.pdf+html ). Tilman et al is one of the papers we cite when making the claim that diet changes are the dominant driver of crop demands. Tilman finds that as incomes increase, on average, per capita crop calorie demands also increase. Although, this relationship levels off a bit in higher income groups.
One of the more striking findings of Tilman's paper is that high income countries like the U.S. and countries in the EU demand more than 8,000 per person per day! That's a lot of calories. But we don't eat those calories directly, rather they are embodied in not only our demands for animal products, but also our increased production of biofuels.
Of course every place is different and the slope of the relationship between income and calorie demands varies. In India where's there's less meat consumption they may show less of this relationship than say China, but the diet changes we are seeing in these countries is consistent with Tilman's findings.
To answer your first point I'm not too familiar with research linking food security to population growth rates. However, if we compare places with more food availability to those with less food availability it seems to me that food secure countries on average have lower rates of population growth. In fact according to the World Bank the lowest income countries typically have the highest rates of population growth.
http://www.worldbank.org/depweb/beyond/beyondco/beg_03.pdf
1) You state "If we used U.S. croplands to grow only crops for direct human consumption, we could feed more than 1.5 billion people. That means the U.S. alone could feed a staggering 1 billion more people on the calories that do not end up in the food system." This is an unrealistic assumption where you are assuming linearity. Assuming that tomorrow a big change in America occurs and all americans favour a change such us the one you propose, part of those "savings", ceteris paribus (and that's where I agree with Brent, we need to look at the roots of problems and no more "sustainable development" out-of-reality nonsense) there would most likely be a rebound effect divested towards other products unless the paradigm of overconsumism changes". Even if that did not happen the possibility of feeding that additional people you mention (which exceeds the population of the US) would require exporting the food (with the associated environmental impacts) plus impredictible effects on the food markets. Non-linearity matters, scale matters, boundaries matter and... ENERGY matters. And that's why
2) You don't take into account that the current state of affairs is unsustainable due to peak oil, peak phosphurus and other peaks that will and are already most likely limiting the human ability to keep on the same exponential growth track that we have been following since the XIXth century (I guess that might be beyond the scope of the article but it is still something to look into and make different scenario-building paths). That said, it would be more interesting to look at how a low-carbon future might look like and at concepts that escape mainstream BAU policies (such usthe ones Brent points out) such us the EROI of food crops (which is basically much higher in pre-industrial societies as recognized by the pioneer on this work Podolinksy or ecological economists such Joan Martinez Allier by means of Via Campesina).
I understand also that finding funding by anything that scapes the minds of big industry and big government and that challenges the status quo might be close to impossible but it would be interesting to look beyond on the issues I laid out.
Anyway, thanks for the article. It was an interesting read for one of my MSc classes.
Best,
Roger