November 16, 2012
By: Nick Buhbe
As we head into November and the Thanksgiving season, my thoughts have naturally turned to some of my favorite fall foods: pumpkin pie, cranberry sauce, and turkey! Thanksgiving is a time to express our gratitude and spend time with family, friends, and loved ones. It is also a time to reflect on the how many of us are blessed but by an abundance of food. The U.S. is somewhat paradoxical, as obesity coexists with hunger in many parts of the country.
More broadly, it is well known that world food production is more than sufficient to feed the global population (read Nan Dale’s, CEO of Action Against Hunger, post), but scarcity remains an ongoing issue for a variety of economic, cultural, and political reasons in the U.S. and the world.
Looking into the future, the dimensions of hunger may become even more extreme: global food production will need to increase by 70 percent to nourish a projected global population of 9.3 billion people in 2050 (UNFAO, 2009). If such increases become a reality, the extent of environmental impacts must also be considered. What are the potential implications of such changes on clean water, global warming, and food security?
Although the consumption patterns of the world’s population should be considered (see references provided), this blog focuses on several elements of agricultural production and their respective environmental consequences.
Water Footprints of Food Production
A recent paper by Mekonnen and Hoekstra (2012) quantified the amount of water necessary to produce agricultural products around the world, which they term water footprints. They included data from both developed (US, Netherlands) and developing (China, India) nations to account for variability due to climates and infrastructure levels. In addition, they quantified water footprints relative to caloric, protein, and fat content (Table 1). For example, Mekonnen and Hoekstra found that the average water footprint per calorie for beef is 20 times larger than for cereals and starchy roots. The water footprint per gram of protein for milk, eggs and chicken meat is 1.5 times larger than for beans.
As shown in the general trends of Table 1, it is unsurprising that foods produced directly (e.g., starchy root and vegetable crops) are much less water-intensive than animal-sourced foods. But there are some other notable trends in the data. For example, fruit crops require approximately 3 times the water, and nuts approximately 30 times the water, as do starchy root and vegetable sources.
Animal protein ranks in four categories with eggs being the least water-intensive, followed by poultry, pork, and goat meat. Lamb is even more highly water intensive, but it is still only two-thirds as intensive as beef production. Production of a pound of beef requires approximately 3 times as much water than does the production of poultry, pork, or goat, and approximately 5 times as much water than does the production of eggs. Compared to root vegetables, beef requires approximately 40 times the water than does the lowly potato (the world’s most popular root vegetable [UNFAO])!
Other Environmental Cost Metrics of Meat Production
Water is not the only resource that is utilized to produce high-protein foods. The amount of grain produced as feed for domesticated animals is an alternative way to directly estimate the environmental cost of meat production. When meat production is measured against the weight of feed, beef remains at the top of the scale with poultry and pork close behind. Compared to the amount of water required (as detailed in Figure 2) lamb and goat require the least amount of grain.
Note that egg production was not included in this evaluation and the goat water footprint (when considered on a ratio basis) in this study was considerably less than that reported in the Mekonnen and Hoekstra 2012 study.
The second alternative metric to consider is the pounds of CO2 emitted as a result of animal husbandry practices. Animals that ruminate (that is, animals, such as cows, with gut bacteria that helps to digest food, but generates CO2 and methane in the process) are the critical factor contributing to CO2 emissions shown in Figure 2. It is no surprise that ruminants rank highest in terms of CO2 emissions. Poultry production-related CO2 emissions are at least half of those reported for other domesticated animals.
Given these environmental costs related to meat production, from both Mekonnen and Hoekstra and Figure 2, it appears that poultry is a good choice when choosing animal-sourced protein. Assuming that turkey production results in broadly similar environmental impact profile to chicken, I’m happy to report that Thanksgiving dinner has a relatively low impact profile due not just to turkey as the traditional focal point, but also by way of using starchy roots and vegetables to augment the dinner menu. Of course, this also brings into question the pumpkin pie-pecan pie debate, but draw your own conclusions for dessert.
Perhaps more importantly from a global perspective, making daily choices to favor turkey over beef or incorporating beans and vegetables into our meals have serious implications not only for our health but also in consideration of the amount of resources needed to produce our foods.
For Thanksgiving, I’ll be sticking with turkey, but the leftovers may be headed for a quiche, or better yet, something with root vegetables, Turkey Sweet Potato Hash sounds tasty!
United Nations Food and Agriculture Organization. 2009. How to Feed the World in 2050.
Mekonnen, M.M. and A.Y. Hoekstra, 2012. A Global Assessment of the Water Footprint of Farm Animal Products. Ecosystems 15:401-415.