SYMP 1-3
Can we feed the world and preserve biodiversity?

Monday, August 10, 2015: 2:30 PM
307, Baltimore Convention Center
David Tilman, Bren School, University of California, Santa Barbara
Michael A. Clark, Ecology, Evolution, and Behavior, University of Minnesota, St. Paul, MN

Global agriculture, which already uses over ~40% of habitable land and emits ~30% of global greenhouse gasses, is likely to double in 40 years. Accelerating global food demand is driven by increasing population and income-dependent dietary changes, called the nutrition transition, that are causing an emerging global pandemic of non-communicable diseases such as diabetes, heart disease and cancers. We evaluate potential global solutions to these diet-linked problems by synthesizing data on diets, health, crop yields, income, population, and environmental lifecycle analyses of hundreds of crops or foods. We first project future global demand for various types of foods and their yields, and next forecast resultant environmental impacts. We then quantify environmental benefits of three potential interventions: increased global food trade based on comparative yield advantages among nations, closing the “yield gaps” of poorer nations, and shifting to diets that help prevent non-communicable diseases.


All three interventions offer substantial benefits and may represent the three most important global policies for the preservation of global biodiversity, while also increasing quality of life in developing nations. Land clearing is the major threat to biodiversity. Closing the yield gap could increase global food 70% and prevent ~600 million hectares of clearing (2/3 the size of the USA). Doubling of the current proportion of crop production traded internationally could save about half that area of land. Shifts to healthier diets, such as the Mediterranean, pescetarian and vegetarian diets, could spare about 500 million hectares while also reducing the risk of diet-related non-communicable diseases such as diabetes, cancer, and heart disease. If combined, these three interventions would allow less land than currently cropped to fully meet global food demand in 2050 while preventing a massive increase in agricultural GHG emissions.  Nature reserves and parks have biodiversity benefits, but ultimately mainly determine which land, rather than how much land, is spared. This is because food is essential; people do whatever they must to obtain it. Ensuring the peoples of all nations a sufficient, secure, and nutritious food supply is a moral necessity. At the same time, decreasing cropland demand is the most important global strategy to save biodiversity. Achieving both goals simultaneously will have a substantial impact on human and environmental health. Advancing agricultural trade, sustainably intensifying yields, and pursuing healthier crops and diets should be a major focus of environmental NGO’s, international health and development agencies, and food and agricultural businesses.