Carrying Capacity of U.S. Agricultural Land: Ten Diet Scenarios

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Authors: Research Article by Christian J. Peters, Jamie Picardy, Amelia F Darrouzet-Nardi, Jennifer L. Wilkins, Timothy S. Griffin, Gary W. Fick

Strategies for environmental sustainability and global food security must account for dietary change. Using a biophysical simulation model we calculated human carrying capacity under ten diet scenarios. The scenarios included two reference diets based on actual consumption and eight “Healthy Diet” scenarios that complied with nutritional recommendations but varied in the level of meat content. We considered the U.S. agricultural land base and accounted for losses, processing conversions, livestock feed needs, suitability of land for crops or grazing, and land productivity. Annual per capita land requirements ranged from 0.13 to 1.08 ha person-1 year-1 across the ten diet scenarios. Carrying capacity varied from 402 to 807 million persons; 1.3 to 2.6 times the 2010 U.S. population. Carrying capacity was generally higher for scenarios with less meat and highest for the lacto-vegetarian diet. However, the carrying capacity of the vegan diet was lower than two of the healthy omnivore diet scenarios. Sensitivity analysis showed that carrying capacity estimates were highly influenced by starting assumptions about the proportion of cropland available for cultivated cropping. Population level dietary change can contribute substantially to meeting future food needs, though ongoing agricultural research and sustainable management practices are still needed to assure sufficient production levels.

1. Introduction

1.1 Relationships between diet and sustainability
One of the most perplexing questions in sustainability science is, “What should we eat?” Within the food and agriculture literature, a strong case has been presented that dietary change is essential for meeting future human food needs (McMichael et al., 2007; Pelletier and Tyedmers, 2010; Godfray et al., 2010; Foley et al., 2011; Smith et al., 2013). By “dietary change,” these authors refer to eating patterns that stabilize, or decrease, livestock production, keep food system environmental impacts within ecosystem limits, and more equitably distribute food to meet global nutritional goals.

This line of thinking is not new. The equation I=PAT, conceived in the 1970s, proposes that environmental impact is a function of population, affluence, and technology (Parris and Kates, 2003). Calls for considering the environmental impacts of food consumption through changes in diet were made decades ago both in popular (Lappé, 1971) and academic literature (Gussow and Clancy, 1986). However, for most of the 20th Century the predominant agricultural science paradigm focused on increasing yield and production efficiency, expanding in the 1980s and 1990s to include ecological impacts of farming but not focusing on food systems (Welch and Graham, 1999). Likewise, nutritional sciences and dietary advice over most of the past century have been guided almost exclusively by evidence on the relationships among nutrients, foods, diets and human health (King, 2007). If strategies for sustainability must address both food consumption and production, then analyses that link agriculture and nutrition are needed.

1.2 Land as a fundamental resource
The food system exerts a broad range of ecological impacts. Biodiversity loss, climate-forcing emissions, nutrient cycle disruption, and competition for land, water, and energy are all cited as reasons to contain agriculture’s environmental impact (Godfray et al., 2010; Foley et al., 2011). Among these impacts, land use is central. Sparing land from conversion to agriculture may be important for protecting biodiversity (Balmford et al., 2005; Lambin and Meyfroidt, 2011). In addition, as highlighted in debates about the merits of biofuels, conversion of native grassland or forest to agriculture causes carbon emissions (Fargione et al., 2008; Searchinger et al., 2008). Both issues provide persuasive arguments against expanding land under cultivation. Yet agricultural yields are not on track to meet projected global increases in food demand (Ray et al., 2013). Potential (and probable) increased demand for bioenergy or carbon sequestration further confounds the land conversion question (Smith et al., 2013). Given all the challenges, understanding the impact of dietary patterns on land use is critically important.

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How to Save the World? The Answer Is in the Soil

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Author: Valentina Valentini

“There is a big difference between dirt and soil,” filmmaker and activist Rob Herring says. “Dirt is lifeless. Soil is life.”

The Need to GROW is a new documentary about an age-old matter—soil. And although soil science is relatively young and unbelievably complex, it’s been a life source for millions of years. With somewhere around six billion microorganisms in a mere tablespoon of soil, these are galactic ecosystems which scientists are just starting to understand.

“These systems evolved over millions of years to optimize delivery of nutrients to plants, hold water in the ground and store carbon in our soils,” explains Herring, who made the film with creative partner Ryan Wirick. “Literally our air, food and water all rely on healthy soil. However, it’s estimated we’re losing 75 billion tons of soil every year. At this rate, the UN estimates that we have 60 years left of farmable topsoil. Not enough people are talking about this.”

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Restoring the Climate: War Is Not the Answer

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Author: Judith Schwartz

Author and climate activist Bill McKibben has published a manifesto to “declare war” on climate change. While I agree about the urgency, I question the wisdom of invoking warfare. For one, how well have our battles against vast, multifaceted problems worked out? (Think: the war on drugs, the war on terrorism, the war on poverty.) Equally important, the language of combat is exactly wrong for addressing climate disruption. Rather, we need to wage peace with nature: to understand how natural systems regulate climate and to ally with the processes that maintain those functions.

But we’re running out of time.

“Increasingly, people are ready for a peace footing with nature.”

Shifting to renewable energy—the core of McKibben’s mobilization—is essential. But this alone won’t avert climate disaster. Even if we stopped fossil fuel emissions this minute, it would take centuries to bring CO2 down to appropriate levels. Plus, what remains unspoken: We could suck all the CO2 we want out of the atmosphere and still suffer the droughts, floods, heat waves and wildfires we now associate with climate change. We’re blind-sided by carbon, as if breaking our fossil fuel addiction were all that’s needed to restore climate dynamics. Climate is too complex to be reduced to a single variable.

Many ecological processes that influence climate reflect the movement and phase change of water. While carbon dioxide traps heat, water vapor acts as conveyer of heat, retaining and releasing heat as it circulates. Consider transpiration, the upward movement of water through plants. This is a cooling mechanism, transforming solar radiation to latent heat embodied in water vapor. According to Czech botanist Jan Pokorny, each liter of water transpired converts 0.7 kilowatt-hours of solar energy, an amount comparable to the capacity of, say, a large room air conditioner. A single tree can transpire upwards of 100 liters of water in a day. That’s a lot of cooling power—not to mention the shade, the drawdown of carbon, and everything else a tree does for us.

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Education for Meaningful Sustainability and Regeneration

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Author: Daniel Christian Wahl

Building a new more sustainable future is surely best done by creating inspiring alternatives rather than criticising the old. DANIEL CHRISTIAN WAHL celebrates the work of  – an educational NGO that is at the forefront of locally focused sustainability education on six continents.

“Whoever you are, no matter how lonely, the world offers itself to your imagination, calls you like the wild geese, harsh and exciting – over and over announcing your place in the family of things.” The poet Mary Oliver reminds us the choice to come home into the community of life is ours, every day anew.

Those of us alive today are the cast for an epic of civilizational transformation. Something the environmental activist and author, Joanna Macy, describes as “The Great Turning.”

As this story unfolds we will see humanity collaborating in the conscious re-design of its collective impact on Earth. This is already happening and this much-needed Re-Generation is on the rise. The biophysical reality of a planet in crisis dictates our design brief: We have to shift from the current degenerative, exploitative and competitive practices to regenerative, productive and collaborative practices.

If we want to co-create a future worth living, all of humanity will have to learn to collaborate. We need to come together in all our wonderful diversity as one Re-Generation facing our common challenge: to re-design our human presence on Earth in accordance with our place in the family of things.

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Special Report: US Organic Farming Hotspots – an Opportunity for Rural Communities?

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Author: Marilyn Borchardt

“For us, cheese has always been a vehicle to achieve this other thing,” Mateo Kehler of Jasper Hill Farm said.

“A vibrant community that’s not completely dependent on globalization. This is our response to globalization: We have the opportunity to extract wealth and redistribute it in our community in a different way.”

Mateo and his brother Andy of Jasper Hill Farm, like all resourceful farmers, understand that making a living in rural America today requires more than just milking cows. And just like the California winemakers of an earlier generation, they set a lofty goal to challenge the best of European cheesemakers.

Can Organic Agriculture Contribute to Increasing Income for the Larger Community?

Do clusters of organic farming activity lead to higher income for farmers as well as others in their community? A recent study suggests that producing organic foods is correlated with lower poverty and increased household incomes in rural communities.

In their economic analysis, Pennsylvania State University agricultural economist, Ted Jaenicke and then-student Julia Marasteanu (who now works at the U.S. Federal Drug Administration) identified counties around the country with high levels of organic agricultural activity where a neighboring county also has high organic activity. Their analysis suggests that clusters of two contiguous hotspot counties is correlated with increased median household income by an average of $2,094 – and reduced poverty levels overall.3

This income increase in organic hotspot counties averages 4.7 percent in relative terms for all people residing in hotspot counties.

At a time when most workers in the U.S. are experiencing stagnant or declining income, what economic development official wouldn’t want to promote such a dramatic improvement in income?

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5 Reasons Why Biodiversity is a Big Deal

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Author: Russell McLendon

“Biodiversity as a whole forms a shield protecting each of the species that together compose it, ourselves included.” — E.O. Wilson, “Half-Earth”

Earth is teeming with life, from huge blue whales and redwoods to tiny bacteria, archaea and fungi. It’s not just the only planet known to host any life at all; it has so many species in so many places we still aren’t even sure how many there are.

We do know, however, that Earth is losing species unusually quickly at the moment. We’re seeing a mass extinction event, something that’s happened at least five times before on Earth, albeit never in human history — and never with human help.

Extinction is part of evolution, but not like this. Species are vanishing more quickly than any human has ever seen; the extinction rate for vertebrate animals is now 114 times higher than the historical background rate. Humans are driving this in several ways, from poaching to pollution, but the No. 1 factor is habitat loss.

This is raising deep concerns about our planet’s biodiversity, which, as biologist E.O. Wilson has pointed out, is like an ecological shield for us and other species. In fact, according to a new study, biodiversity loss has crossed the “safe” threshold in most of the world, leaving many ecosystems in danger of collapse.

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Food Tank: Polyfaces

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Author: Lani Furbank

The Australian-based nonprofit Regrarians recently released a documentary about Joel Salatin’s Polyface Farm, titled “Polyfaces.” The film showcases the unique and sustainable farming style pioneered by the Salatin family in the Shenandoah Valley of Virginia. It examines how these holistic practices regenerate landscapes, communities, local economies, human health, and soil.

Regrarians works with farmers, communities, and government organizations internationally to teach and implement regenerative agriculture.

The film was produced over four years by Lisa Heenan, Isabella Doherty, and Darren Doherty, a family from Australia who was inspired by Polyface Farm and wanted to share the farm’s work with the world.

Polyfaces premiered in New York and Los Angeles earlier this year and qualified for the Academy Awards. It also won several awards, including Best Documentary at the Silver Springs International Film Festival in Florida, the Minister of Agriculture Award at the Life Sciences Film Festival in Prague, a Gold Remi at the WorldFest Film Festival in Houston, and the Festival Spirit Award at Weyauwega International Film Festival in Wisconsin.

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Lakota Lead Native Americans, Ranchers and Farmers in Fight Against Dakota Access Pipeline

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Author: Jason Coppola

Amidst the cries of “protect our water, protect our land, protect our peoples,” Native Americans, ranchers and farmers are standing their ground along a highway in North Dakota. They are blocking the crews of Energy Transfer Partners — a Dallas-based company whose workers are protected by both police and armed, private security personnel — from accessing the site of the construction of the Dakota Access Pipeline.

The roughly 1,200-mile-long pipeline would transfer about a half million barrels of oil a day from North Dakota to Illinois. Opponents of its construction worry that a leak or rupture would spell disaster for not only the Standing Rock Indian Reservation, but for all communities along the Missouri River that depend on it for drinking and agriculture.

At least 10 arrests have been made. Morton County Sheriff Kyle Kirchmeier told the Bismarck Tribune that those arrested “were not staying within bounds set by law enforcement and getting in the way of surveyors working on the pipeline.” The arrests included a pediatrician and a grandmother who allegedly crossed the highway to check on a buffalo pasture.

As reported by Truthout in May of this year, Lakota youth, protesting the proposed construction of the pipeline, began a relay race from their Spirit Camp in Cannonball, North Dakota, to the office of the Army Corps of Engineers in Omaha, Nebraska, to deliver a petition against the pipeline. The Corps later decided to grant the necessary permits and green light the pipeline’s construction.

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Four Important Lessons from Cuba’s Urban Food Survival Strategy

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Author: Aurel Keller

Cuba has come a long way since the collapse of the Soviet Union, when the loss of imports crucial for the island nation’s industrial agriculture system—such as chemical pesticides and fertilizers—left Cuba with a severe food crisis in the 1990s. Today, Cuba has become a regional leader in sustainable agricultural research. Within its practices and institutions lies a model for localized and small-scale urban agriculture.

With the loss of the Soviet market, which had imported sugar at subsidized prices, and the fall of global sugar prices in the late 1980s, sugar monoculture production in Cuba collapsed. Out of necessity, Cuba underwent a social, scientific, and economic push toward self-sufficiency. This shift required radical change for the authoritarian communist state as desperation and cooperation drove innovation in sustainable agriculture and urban farming. Although Cuba’s successes relied on country-specific policy adoptions and favorable geographic conditions, the country’s scientific frameworks and practices are widely applicable in other regions.

Reforms Propelled by the Government

Cuba’s success hinged on the adoption of Article 27 of the constitution in 1992, which recognized the state’s innate duty to ensure the sustainable use of resources and to protect the nation’s environment and people. The Cuban state and the Ministry of Agriculture instituted austerity measures, re-adjusting priorities and resources into support roles. State companies in many sectors became employee-owned co-ops, and small-farm distribution programs were greatly expanded. Realizing the need to meet the population’s basic food needs with limited resources, funding for agricultural research infrastructure was expanded to optimize low-input, small-scale farming. The government stepped back from direct management and worked with grassroots organizations and co-ops to provide support through extensive research partnerships to optimize and spread beneficial practices.

Grassroots Organizations and Co-ops Were Key

Grassroots organizations—representing small-scale farmers, animal producers, and agricultural and forest technicians—became essential in forming cooperatives and spreading services and education in Cuba. The small farmer organization, ANAP, has been active since the 1980s, working with farmers and the government to teach beneficial practices and create farmer’s cooperatives—groups of farmers who combine their resources and create employee-owned businesses that provide production, credit, and service assistance. Initially slow, the spread of farm co-ops grew once President Fidel Castro recognized their benefits, with official support commencing in 1987, and picked up speed as land-distribution and support programs expanded. Working with agricultural research outposts and universities, ANAP was instrumental in facilitating the extensive spread of research extension programs through its network, as well as propagating resulting improvements. Many peasant farmers were members of ANAP and participated in co-ops, successful to the point of producing 60 percent of produce on 25 percent of worked land in 2003.

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Wildfires Are Getting Worse: Time to Rehydrate Our Landscapes

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Author: Judith Schwartz

The west is still in the thick of wildfire season and 2016 is already one to leave Smoky the Bear in tears. California is seeing a 20 percent uptick in fires compared to 2015—itself a rough fire year—while a fast-moving blaze has virtually destroyed the California town of Lower Lake. A story in today’s Washington Post grimly begins: “California is burning.”

While fire is always part of nature, many attribute its increased frequency and intensity to climate change. Certainly, that makes sense: longer stretches of warm weather and earlier snowmelt create a fire-friendly scenario. But what does this connection do for us, beyond providing another reason to rue the continued assaults on our climate? For the terms “climate change” and “global warming” elide the dynamics that create the constellation of factors that, collectively, we call climate. However, by zeroing in on the ecology of fire-prone regions, we can find ways to minimize the risk and severity of the fires that threaten homes and wilderness areas—not to mention the lives of firefighters.

For example, since arid conditions beckon fire, we can ask how healthy environments maintain moisture. Plentiful rain is one obvious answer, but equally important is what happens to rain once it falls. Enter “green water”, or water held in soils. We generally think of freshwater in terms of lakes and rivers, but two-thirds of rainfall becomes green water. When rain falls on living soil that’s rich in organic matter, it stays in the system and sustains plant and microbial life. Rain that falls on soil depleted by tillage or chemicals streams away, as does all the rainwater that strikes concrete or asphalt. Dry, degraded soil (read: dirt) doesn’t absorb water, thirsty though it may be. For every one percent increase in soil organic matter, soil stores 20,000 gallons of water per acre.

Historically, our western landscapes were kept hydrated in part by beavers. According to Brock Dolman of The WATER Institute’s Bring Back the Beaver Campaign, the winsome rodents act as “water engineers”. By building dams they harvest water and direct its flow, and the moist soil that surrounds the pools yields lush vegetation. Beavers, he says, serve as ecological “shock absorbers” so that land is less susceptible to drought and fire. Beavers are native to much of California, and were numerous prior to the early nineteenth century, when they were mostly wiped out. (Water-wise, California’s “fur rush” was a bigger deal than the Gold Rush.) Nationwide, today beavers number around 10 million, down from an estimated 200 million when Europeans arrived on our shores.

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