March 2009 Archives

by Christian Peters

Modern people in industrialized countries ask themselves a question that most people have not needed to ask over most of human history: “Where does my food come from?” The fact that the answer is not immediately obvious testifies to the completeness of our transition from an agricultural society to an industrial one. Food often travels great distances from the farm field through processing facilities, distribution channels, retail outlets, and ultimately to a person's plate. As a result, the journey of food remains a mystery to most of us.

To some extent, this transition has been a success. For most of the twentieth century, the principal goal of agricultural research was to increase economic efficiency of production, thus making food cheaper and more abundant. Trends in consumption and the percent of disposable income spent on food show that these efforts were effective. In the U.S., for example, the share of income spent on food dropped from 24% in 1929 to 11% in 1998 (USDA Economic Research Service, 2000). Food has become much more affordable, but this transition has aggravated health problems related to excessive consumption. In addition, the increased intensity of agriculture necessary to enable this increase in abundance has raised many issues about the environmental sustainability of the food system.

Among the many sustainability issues surrounding the food system, dependence on non- renewable energy sources and growing concern about climate change present a clear challenge. Energy consumption grew 20-fold between 1850 and 2000 (Holdren, 2008). However, limitations to increasing the supply of fossil fuels or regulations to reduce greenhouse gas emissions may cause this trend to reverse in the twenty-first century. The possibility of society entering a period of “energy descent” within this century suggests that we learn more about the journey of food from farm to plate. Specifically, we need to understand which elements of our food system are most sensitive to changes in the availability of energy so that society may plan strategically. One course of action that has been proposed is to increase reliance on “local” sources of food. This paper will address two fundamental questions related to this strategy as it applies to Tompkins County: “How much food could Tompkins County provide for itself?” and “What is the capacity of other places in New York State?” Answers to these questions will begin to shed light on a larger issue — how much of our food should be produced locally?

How much could Tompkins County produce?

One way to examine the capacity of Tompkins County to localize food production is to estimate the number of people it could feed based on the potential productivity of its agricultural land. On one level, this is an elementary approach. It considers only the nutritional needs of the population and the capacity of the available soils and climate to produce food. The necessary human capital and physical infrastructure for creating a local food system are simply assumed to exist or to be possible to develop. Nonetheless, calculating the capacity of land to meet human nutritional needs is sufficiently complex to constitute a valuable first step.

Such an analysis has been conducted for New York State. It examined a wide range of possible diets and estimated both the land requirements of each diet and the number of people that could be fed from the agricultural land within the state (Peters et al., 2007). The methodology estimated food intake based on the nutritional needs of the New York State population, preferences for individual foods, and a range of assumptions about the amount of meat and fat in the diet. Land requirements for the human diet were calculated based on estimated food intake, adjustments for losses and inedible portions, New York State crop yields, and standard livestock feeding practices. The carrying capacity was estimated based on the land requirements of each diet and the amount of cropland and pasture available, with limitations placed on the amount of land that can be tilled.

Given the complexity of the methodology, let us assume that Tompkins County is just like New York State, only smaller. Thus, the number of people that the county could feed (PTompkins) can be estimated as a simple product of the total number that could be fed in the state (PNew York State) and the proportion of available agricultural land in Tompkins County (ATompkins) relative to that available in New York State (ANew York State):

PTompkins = PNew York State × (ATompkins/ANew York State)

For purposes of illustration, let's estimate capacity to feed the population a diet with 6 ounces of cooked meat and eggs daily and 30% calories from fat. This diet reflects the current American preference for meat and eggs as a protein source yet adheres to the recommended limit of no more than 30% of total calories from fat. The statewide analysis estimated that New York could theoretically feed 4.0 million people such a diet from its 5.0 million acres of harvested cropland, cropland pasture, and permanent pasture (Peters et al., 2005; Peters et al., 2007). According to the 2007 Census of Agriculture, Tompkins County has 70,150 acres of land in harvested cropland, cropland pasture, and permanent pasture (USDA National Agricultural Statistics Service, 2009). Based on the equation above, the agricultural land of Tompkins County could theoretically feed 56 thousand people — 56% of the estimated 2007 population for the county (101,055, according to the U.S. Census Bureau, 2009).

This estimate should be taken with several grains of salt. It is based principally on the capacity of the available land and does not account for many of the social or economic factors, such as food processing infrastructure, that might further limit the capacity for Tompkins County to supply its own food. Nonetheless, it provides a baseline estimate that could be adjusted to account for changes in crop yields, availability of land, and different diets. This baseline suggests that the agricultural land of the county has significant potential to meet the food needs of the county, but that the county could not be self-sufficient.

Where would neighboring counties get their food?

Of course, Tompkins County is not the only county in the state that would like to be fed. Thus, it is reasonable to consider a more complex analysis that accounts for the needs of surrounding population centers. Such an analysis has already been conducted for New York State. The research attempted to map potential local foodsheds, geographic areas that could theoretically provide the food needs of a population center (Peters et al., 2009). The study used geographic information systems and optimization models to determine how much food the major population centers of New York could supply from within the state if all agricultural land were used to feed people as “locally” as possible.

The foodshed model used the statewide analysis of the food requirements of the human diet as a foundation. Food production capacity was then estimated spatially based on the distribution of agricultural land and the productivity of the underlying soils. Food needs were also estimated over space based on the location and population of the state's urban centers. This data on potential food production capacity and estimated food needs were organized in an optimization model that sought to minimize “food miles.” In other words, it allocated the available food production potential in the shortest possible distance.

The analysis did not produce results specific to Tompkins County, but the summary results provide the basic story. According to the model, the larger cities of upstate New York (Ithaca included) could theoretically supply 84% of their food needs within an average distance of 32 miles from the city center (Peters et al., 2009). The smaller cities fared even better and could theoretically supply 98% of their needs within an average distance of just 16 miles. In contrast, the model allocated New York City (NYC) just 2% of its food needs even though it drew on land an average distance of 165 miles from city center. Since the greater NYC area contains the majority of the state's population, this is a serious deficiency.

Again, these results should be interpreted with caution. The analysis shows that with respect to food, the distribution of land to people is nearly in balance in upstate New York. However, this balance is upset once the population of NYC is included. This does not imply that NYC cannot or should not obtain some of its food from local sources. Rather it points out that there is simply not enough land to meet the food needs of all people in all cities of New York State. The geographic area of analysis would need to be much larger to see how “local” the NYC food supply could be.


These two attempts to examine the food production potential of Tompkins County should not be seen as immutable estimates. Rather, they provide a quick estimate of the capacity of the county to meet its food needs and a sketch of the thinking behind the calculations. The details of the analyses, while nuanced and important, are covered in depth in the original publications. The intent of this article is simply to initiate a larger discussion.

Acknowledging these limitations, the two examples suggest that while Tompkins County may have a significant land base relative to its population, it is not an island. Rather, it is part of the very populous Northeast U.S. region. In the context of planning for energy descent, Tompkins County lies in the “backyard” of the nation's largest city. Thus, local needs for the county's agricultural land will have to be balanced against the demands of this major metropolitan area. After all, New York City already relies on upstate New York for its water supply and many of the dairy products the city consumes.

Since all food cannot be local, we should think strategically about which foods would be most important to provide locally. This will vary from location to location and from one food to another. For example, NYC is a major seaport with access to the most energy efficient form of transport available (shipping over water), whereas many towns and villages in New York are accessible only by road. Similarly, grain is easy to store and can be transported by slow, energy efficient methods, while fluid milk is bulky and perishable. It needs to be moved quickly. Such issues will clearly influence which foods are most important to supply locally and which locations have the greatest need for access to locally produced foods. We will need to think in this broader context if we are to plan strategically about how to adapt our food systems to the challenge of energy descent.


Holdren, J.P. 2008. Science and technology for sustainable well-being. Science 319 (5862): 424-434.

Peters, C.J., Bills, N.L., Lembo, A.J., Wilkins, J.W., and Fick, G.W. 2009. Mapping potential foodsheds in New York State: A spatial model for evaluating the capacity to localize food production. Renewable Agriculture and Food Systems 24 (1): 72-84.

Peters, C.J., Wilkins, J.L., and Fick, G.W. 2005. Input and Output Data in Studying the Impact of Meat and Fat on the Land Resource Requirements of the Human Diet and Potential Carrying Capacity: The New York State Example [R05-1]. Department of Crop and Soil Sciences, Cornell University, Ithaca, NY.

Peters, C.J., Wilkins, J.L., and Fick, G.W. 2007. Testing a complete-diet model for estimating the land resource requirements of food consumption and agricultural carrying capacity: The New York State example. Renewable Agriculture and Food Systems 22(2):145-153.

U.S. Census Bureau. 2009. State and County QuickFacts for Tompkins County, New York. Available at Web site: (verified 1 March 2009).

USDA Economic Research Service. 2000. Major trends in U.S. food supply, 1909-99. FoodReview 23(1): 8-15.

USDA National Agricultural Statistics Service. 2009. 2007 Census of Agriculture. Available at Web site:,_Chapter_2_County_Level/New_York/index.asp (verified 1 March 2009).

Additional Resources

U.S. Food consumption data:

Census of Agriculture Query Tool

Local Foodshed Mapping Tool

Planning for Energy Descent

Some time in the next 30 years, life will start to become very different from what it is now. By mid-century we will use much less energy; we will live every aspect of our life much closer to home; and we will be much poorer in material terms, because energy and wealth are basically the same thing in an industrial society.

Energy descent — a radical reduction in our use of energy — is certain, but it’s not clear yet which of several factors will cause it to begin. Perhaps we will decide to do the right thing about climate change and reduce our CO2 emissions 80 or 90 percent, which would require changes almost that large in our actual consumption of energy. And there are other ways we might experience a radical reduction in our use of energy; for example, economic collapse, or an expanded war in the middle east. But the factor that makes energy descent a sure thing and sets the theme for this century is "peak oil" — the leveling off of global oil production and then its eventual and inexorable decline.

The timing of the peak is debatable, with forecasts ranging from 2005 (that is, already here) to 2030. But most credible estimates agree with the U.S. Army Corps of Engineers, which concluded in a recent study that "world oil production is at or near its peak," and with the director of research at OPEC, who said recently that "we are at, or near, the production peak of world oil, if not on the downward slope."

After the peak, the growing gap between falling world oil production and ever-increasing global demand will send prices skyward, with economic results that can only be imagined but will certainly include greatly restricted mobility due to the high cost of fuel and much higher prices for most goods, including food. The result will be less disposable income, a life lived closer to home, and a greater reliance on the goods and services that can be provided locally. Since the supply of oil and other fossil fuels is finite, this outcome is guaranteed. The only question is, Shall we plan for what we can see coming, or just let it happen to us?

A group of area citizens, TCLocal, has begun planning now. TCLocal contributors are committed to researching various aspects of energy descent in Tompkins County and writing up a preliminary plan for each aspect based on purely local challenges and resources. This is one such plan.

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