|Fig. 1: Food waste per capita in kg/year for main geographical regions, from UN FAO data. (Adapted from Gustavsson et al. )|
In 2011 the United Nations' Food and Agriculture Organization (FAO) enlisted the Swedish Institute for Food and Biotechnology to study global food waste. The resulting report indicates that a staggering one third of all food produced for human consumption is wasted.  The following document reports some food waste statistics and describes the origins of the most crucial of these figures.
Beyond estimating that roughly one third of globally produced food is wasted, the FAO report breaks down waste into pre-consumer (i.e. harvest, processing, distribution, and retail) and consumer components, as seen in Fig. 1.  This division highlights the low-efficiency links in the food supply chain in different world regions. One particularly striking result is that consumer waste in Europe and North America is roughly ten times as large as that in Sub-Saharan Africa and South/Southeast Asia.
In low-income countries, food waste is predominantly pre-consumer. Due to financial, managerial, technical, and infrastructural limitations in harvesting, storage, packaging, refrigeration, marketing, and transportation, developing economies are simply unable to manage the volume of food they produce.  Once in the hands of consumers, food in developing regions is seldom wasted.
In contrast, food waste in middle/high-income countries is caused by both pre-consumer and consumer inefficiencies. Consumer waste has a number of causes, but most are ultimately connected to the simple fact that waste is affordable in wealthy nations. Pre-consumer waste results mostly from misguided economic decisions, unlike in developing regions where systematic insufficiencies are the dominant force in the supply chain.
To generate these food waste statistics, the authors of the FAO report tabulate known food sources and sinks, construct a mass flow model, and solve for the wasted food (only edible food mass meant for human consumption is considered). Their data originates from the FAO's 2009 Statistical Yearbook and 2007 Food Balance Sheets, sources that rely largely on FAO questionnaires and national publications and are thus susceptible to error.  Nonetheless, the waste estimates represent the UN's best efforts.
|Fig. 1: The solid red line shows the percentage of available food wasted in the U.S. as a function of time, computed by Hall et al. using UN FAO statistics. The dashed orange lines indicate 95 percent confidence intervals. (Adapted from Hall et al. )|
The particularly excessive food waste in wealthy nations like the United States - and the correspondingly large potential for improvement - deserve a closer look. In 2012 the National Resources Defense Council (NRDC), a prominent American environmental action group, published an account of U.S. food waste.  An excerpt from that report demonstrates the scope of the issue: "Getting food to our tables eats up 10 percent of the total U.S. energy budget, uses 50 percent of U.S. land, and swallows 80 percent of freshwater consumed in the United States. [3-5] Yet, 40 percent of food in the United States today goes uneaten." 
Forty percent of food, wasted. To compute this stunning figure, Hall et al. from the National Institute of Diabetes and Digestive and Kidney Diseases compare food produced (inferred from UN FAO statistics on the U.S.) to food consumed (estimated using U.S. bodyweight data and a model of human metabolism).  Fig. 2 depicts this estimate of food waste, indicating a clear increase over the last few decades. This trend is corroborated by a commensurate increase in the mass of solid municipal food waste.  Based on the assumptions made by Hall et al., these figures are thought to be conservative estimates.
Food waste contributes to a number of salient challenges facing humanity in the 21st century. The first is global climate change. According to the U.S. EPA, decomposition of uneaten food accounts for 23 percent of all U.S. methane emissions.  Add this to the emissions generated to produce the roughly 40 percent of food wasted in the U.S. and the immense impact on the global climate starts to become clear.
Global use of natural resources is also driven by food waste. Thirty-two percent of freshwater, 20 percent of land, and 4 percent of energy used in the U.S. goes to producing food that is not eaten. [2-5] Though U.S. waste is greater than in other nations, a rough extrapolation of these numbers to the global scale implies a dire need to reduce inefficiencies in the food supply chain.
Resource scarcity in turn underscores food insecurity in a world where nearly a billion people suffer from chronic hunger.  The FAO estimates that food production must increase by 70 percent by 2050 to support the forecasted 9.1 billion people with increasingly meat-dependent diets.  This is a tall order, but there is hope: The U.K.'s Government Office of Science estimates that cutting current food waste in half would effectively increase our food supply by 25 percent. [2,7] Because it takes 4 to 40 calories of energy to produce one edible calorie of animal products (this loss is not part of the calculations of food waste discussed above), reduction of meat consumption is also a powerful strategy to reduce resource usage. 
Finally, substantial economic gains will result from a more efficient food supply chain. The consulting firm McKinsey & Company reports that, including the cost of implementing necessary changes, over $125 billion could be saved annually from eliminating global food waste.  Indeed, the grocery retail chain Stop & Shop now saves an estimated annual $100 million due to waste reduction policies implemented in 2008. 
Education is a solid starting point for battling the profligate inefficiencies in our food supply system, and the recent reports by the FAO and the NRDC constitute excellent resources for further reading. In particular, the 2012 NRDC analysis provides detailed insight into causes of food waste and mitigation strategies. Interested readers should start by perusing these clear, accessible documents. Reducing our massive excess will likely increase food security for the global population, make better use of natural and financial resources, and decrease greenhouse gas emissions. We must take action.
© Justin Briggs. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
 J. Gustavsson et al., "Global Food Losses and Food Waste," Food and Agriculture Organization of the United Nations, 2011.
 D. Gunders, "Wasted: How America Is Losing Up to 40 Percent of Its Food from Farm to Fork to Landfill," Natural Resources Defense Council, Position Paper IP:12-06-B, August 2012.
 M. E. Webber, "How to Make the Food System More Energy Efficient," Scientific American, 29 Dec 2011.
 R. N. Lubowski et al., "Major Uses of Land in the United States, 2002," U.S. Department of Agriculture, 2002/EIB-14, May 2005.
 C. Osteen, J. Gottlieb and U. Vasavada, "Agricultural Resources and Environmental Indicators, 2012 Edition," U.S. Department of Agriculture, 2012/EIB-98, August 2012, Ch. 2.1.
 K. D. Hall et al., "The Progressive Increase of Food Waste in America and Its Environmental Impact," PLoS ONE 4, e7940 (2009).
 "The Future of Food and Farming, Final Project Report," United Kingdom Government Office for Science, 2011.
 R. Dobbs et al., "Resource Revolution: Meeting the World's Energy, Materials, Food, and Water Needs," McKinsey Global Institute, November 2011.