Global Land Use Implications of Dietary Trends: A Tragedy of the Commons

Abstract

Global food security and agricultural land management represent two urgent and intimately related challenges that humans must face in the coming decades. Here, we quantify the changes in the global agricultural land footprint if the world were to adhere to the dietary guidelines put forth by the United States Department of Agriculture (USDA), while accounting for the land use change incurred by import/export required to meet those guidelines. We analyze data at country, continent, and global levels. USDA guidelines are viewed as an improvement on the current land-intensive diet of the average American, but despite this our results show that global adherence to USDA guidelines would require up to 1 gigahectare of additional agricultural land--roughly the size of Canada. The results also show a strong divide between Eastern and Western hemispheres. Because countries increasingly import most of their food, meeting USDA guidelines could cause a Tragedy of the Commons, where self-interested actors race to over-exploit the shared resource of global agricultural lands. National dietary guidelines and practices thus need to be coordinated internationally in order to spare our remaining natural lands, in much the same way that countries are coordinating greenhouse gas emissions.