I step out of the truck and bounce my shoulders up and down in a feeble effort to generate warmth. Above me, the sky stretches in every direction, without a single cloud marring its deep, sharp blue. Around me there is plainness, shades of brown and grey, and the rectangular shapes that tend to dominate industrial agricultural landscapes. I ask as casually as possible if I can go say hello to the cattle, and my host complies. I am astounded by his generosity, and I wonder if it springs from apathy, pride, or oblivion. The ongoing controversy over animal feeding operations swells large in my mind, and I arrived at this 30,000-head feedlot today assuming that someone who works in an industry vilified by environmentalists, food purists, and animal rights activists alike would be on guard. But he takes no issue with my camera, my questions, or my short walk over to the closest pen of complacent beasts destined for the great American dinner plate.

A very long fence holds a concrete trough at its feet, where the animals’ meals are delivered. The cattle stand about nonchalantly just on the other side of this fence, until I cross an invisible line. They suddenly make haste toward the far end of the pen, turning their sides and backs to me and awkwardly bumping into each other as they go. The pen is roughly the area of an Olympic-size swimming pool – they don’t get very far. This small bit of exertion leaves several of them huffing clouds of breath into the frigid air, obese creatures that they are. Fat cows make for good slaughter, and this crowd is clearly fulfilling their one and only assigned task in life, which is to pack on the pounds.

I stand still for a minute and then walk slowly, trying to keep my subjects from moving too much. I want a good look. As I stare at one, trying to decide if she is stupid or majestic, another catches my eye. Her body is exactly perpendicular to my line of sight, giving me an unobstructed view of a steady stream pouring forth from halfway between her front and back legs – the lowest, roundest point of her considerable girth. This moment is embarrassingly poignant for me, because, after months of intensely researching bovine urination, I have just witnessed it for the first time. It’s funny to see it happen in an apparently innocuous and banal way, when I have come to think of cow pee as a threat to human health.

Hardworking farmers toil endlessly to maintain the constant and enormous flow of foodstuffs into our stores, restaurants, homes and bellies. They can’t do this without fundamentally altering our natural systems. This is of great concern to all of us. Those who pay close attention to the topic of food and the environment typically consider feedlots like the one I’m visiting public enemy number one, and some have worked hard to educate the public about the sins performed on meat’s way to the supermarket. Loud and bitter are the disparagements of cows-as-meat-machines who live out their last days standing knee-deep in their own manure. Fed unnatural diets of corn and soy that both fatten and sicken them, the animals must be given large quantities of antibiotics. The persistent presence of such medicine – which also promotes maximum growth – facilitates the development of treatment-resistant viruses that could infect humans. Huge swaths of the US’s agricultural land goes to support the fertilizer-, pesticide-, and water-hungry crops grown to feed cattle instead of people. The run-off from those fields pollutes streams, rivers, and wells. Vast ponds of manure belch climate-warming gases. These stand out as the more infamous impacts of what some see as a complex scheme to maintain the wealth of a few meat company executives at the expense of the health of many.

Such is the distasteful scenario described for us in many a book, article, and documentary film fueled by anger over our industrial food complex. And yet, I have often wondered if this kind of vigorously painted picture is reality or a caricature of it.

Feedlot cattle might not be skipping merrily through fields of emerald grass, but their compromised existence gives millions of people affordable protein. The $79 billion beef cattle industry, which roots 800,000 ranches across the nation in the cowboy way of life, also cannot be ignored. These ranches birth the cattle and raise them through the grass-fed stage of their life, before sending them off to the feedlots. Not only do ranches provide jobs – as do other parts of the beef-supply chain – but they can provide protection for open land that might otherwise go to development. So, then, how does the damage caused by beef-making compare to its benefits? Is industrial agriculture so very wrong, or just unpleasant to think about? Maybe enviro-foodies like me pat ourselves on the back all the way home from the local farmstand as we frown down on what is, in truth, the necessity of feeding everyone.

A peek into the hidden world of the food system reveals extraordinarily complexity – a pulsing, intricate maze of veins ferrying human nourishment from seed to stomach, around the globe. Each of these veins touches the environment, the economy, and thus people’s lives, in innumerable and seemingly immeasurable ways. Over-simplified statements that alternatively condemn or praise industrial agriculture overlook the transient, complex nature of these entanglements.

I decided to try and untangle such a question. I wanted to take one vein, find one place where it collides with people’s lives, and shine a very bright flashlight on it. That’s how I ended up in this feedlot.  Beef is one of the most controversial food items out there, so I was naturally drawn to the vein that brings a calorie from a blade of grass or a kernel of corn to a cow, to a slaughterhouse, and finally to a hamburger in a diner. I looked for an intersection between the beef supply chain and peoples’ lives, and I found it in the release of ammonia from urine. As it turns out, there is a critical mass of data on cow pee.

Because I chose urine, or rather, because urine chose me, I am privy to the silent chain of events unfolding around the relieved cow that I’m walking away from. Ammonia is slowly drifting above the herd and into that deep blue sky, to join an invisible, scentless, lighter-than-air river of pollution on its way into the stratosphere. Once there, ammonia has the opportunity to mate with any number of other gases before returning to ground level. Sulfur dioxide and nitrous oxygen, the refuse of cars and power plants, are particularly attractive partners. The offspring of ammonia and these gases are minute particles, much too small for the eye to see, and capable of riding the wind many hundreds of miles. Once these tiny, newborn industrial byproducts make it down to our breathing level, they float silently into our lungs and make us cough. They become the seeds of respiratory illnesses that can shave years off people’s lives without ever making their presence known.

I like that I know this. I like this kind of robust information. It gives me the same feeling – or perhaps illusion is a better word – of intimacy and control that also comes with a trip to the farmer’s market. But the story of ammonia alone is just that – a single story. We don’t know how it stacks up against the many places along the beef supply chain where human lives are touched in a good way. How can one begin to compare two things like the illnesses of a few and the full stomachs of many?

Environmental economists use a single, familiar metric: dollars. We know how much beef products add to the economy: about $79 billion in 2011. This figure captures the value of jobs and the full stomachs the meat industry provides. But what is the value of the harm caused by bringing beef into being? Consequences like pollution that involve complex systems are exceedingly difficult to attach a dollar figure to. And that’s exactly why they are rarely considered to have an economic cost.

Think of cow pee. Seventy two million separate animals, scattered around the country, relieve themselves at all times of the day and night. Invisible gas travels hither and fro and performs complex mating rituals far above the earth’s surface. The offspring scatter widely, making their way to people who could not begin to know, much less report, why their health has deteriorated.

Happily, this series of events occurs within a set of well-understood natural phenomena, which allowed environmental economist and Middlebury College professor Nick Muller to build a computer model that simulates this entire system. Leaning on the work of atmospheric chemists, wind scientists, and public health experts, he traced the causes and effects of ammonia and five other air pollutants from their many sources all the way to patients checking into the hospital. Pollution causes disease, and disease creates healthcare costs. There are a few other issues of concern– ecosystem disruption, for instance – but human health is the most significant way that ammonia causes damage.

After several years and thousands of modeling hours, Muller’s computer spit out a deceptively simple spreadsheet listing the cost of a ton of ammonia released in every county in the US. The costs are different everywhere – they depend largely on how many people live in the area. I combined this data with information about cattle populations and the amount of ammonia that each animal releases. The resulting estimate: beef cattle-generated ammonia causes $1.5 billion in damage annually for the entire continental US. This is the sum total of a multitude of coughs, or rather, the medical fees that result from those coughs. I think of those billions of bits of industrial by-products as dollar bills, blowing in the wind above my head as I walk back toward the truck.

$1.5 billion doesn’t hold a candle to $79 billion, so it’s tempting to suggest that we have arrived at a conclusion: in this very narrowly focused assessment, the benefits of food production outweigh the harm. But there is a lot of geographic nuance in those numbers. For example, 2.2% of the feedlot cattle, mostly near major metropolitan areas, cause 30.3% of the damage from feedlots. That makes a lot of sense – without a large availability of people to affect and other pollutants to mix with, ammonia can’t cause many health problems.

A $3.10 quarter pounder hamburger can help translate the location issue. If we include the cost of the damage caused by the ammonia emitted during the making of a quarter pound of beef, the hamburger would cost $3.11 if it was produced in Washington County, Maine. If it hailed from Macomb County, Michigan, the cost would be $8.24. DuPage County, Illinois would turn out a $48.39 quarter pounder.

This suggests a straightforward management decision. If we want to have our beef and eat it too, we just need to move the cities of cattle away from the cities of people. Of course, the moment the scope of the investigation widens, complexity and confusion return. Since ammonia alone doesn’t cause health problems, we would have to consider assigning a portion of the healthcare damage to other offending industrial pollutants. Yet another kettle of fish: cattle burp methane, a potent climate-warming gas. Their collective belches cause $3 billion in damage, if we assume that the cost of carbon dioxide-equivalent gases released into the atmosphere is $12 a ton. This number was developed with a model analogous to Dr. Muller’s – and it is hotly debated. Some have suggested that it could be as high as $900 a ton, others, as low as a few cents.

These issues provoke questions that, while deeply theoretical, have a gravity that makes them worth considering. If we added all the costs of the damage caused by beef production – water pollution, the depletion of aquifers and rivers, the risk of medicine-resistant super-viruses, perhaps even the suffering of the cattle as they live out their short lives, among many others – how close to that $79 billion would we get? How close would we need to get before we decide that that the benefits of having beef aren’t worth the cost?