If you are engaged in ongoing dialogues about the future of food—our ability to both feed and nourish the predicted 9.5 billion–person global population by 2050—then you have probably heard some of the following statements: We will need to produce approximately 70% more food by 2050 and that extra food must come from finite resources, that is, land, water, and energy use that should not exceed, and probably should be less than, current levels to be secure and sustainable.1 The middle class worldwide is expected to dramatically increase in the coming decades, and dietary preferences will shift food demand accordingly. Health outcomes and environmental effects, and especially the tradeoffs that happen between them when we adjust to changes in the environment, need to be understood as parts of the same system, not variables that can be considered independently. Today, research and policy experts are thinking about sustainable food systems in ways that expand upon the “triple bottom line” of environmental, social, and economic sustainability to also include sustainability in terms of health.2
Economic, social, and environmental sustainability as well as health are needed for sustainable food systems.
Goals for global food system stakeholders are frequently drawn from the sustainable development goals identified by the United Nations.3 The topic of food and agriculture weaves its way through most of the 17 sustainable development goals (Table); improving nutrition and farming around the world will have significant and lasting impacts on solving hunger, naurally, but also on education, equality, climate, economic growth, and all major areas of environmental performance.
The dairy industry is developing the science needed for sustainable food systems both to understand its past and present performance and to continue to improve its environmental footprints while ensuring the nutritional and health profiles of its products. To measure sustainable diets and food systems, multiple metrics are needed rather than single or limited criteria that cannot adequately compare the burdens and benefits of different systems.4 For example, greenhouse gas emissions per calorie was, until recently, a common default measure of food “sustainability.” Because refined sugars have some of the lowest emissions per calorie, this metric, taken at face value, would lead to dietary recommendations that are incompatible with desired health outcomes.2 The Food and Agriculture Organization of the United Nations (FAO) addressed this limitation when it included a much wider range of elements in its definition of sustainable diets, which incorporates everything from low environmental impact to cultural acceptability.5
Sustainable diets are those diets with low environmental impacts that contribute to food and nutrition security and to healthy life for present and future generations. Sustainable diets are protective and respectful of biodiversity and ecosystems, culturally acceptable, accessible, economically fair and affordable, and nutritionally adequate, safe, and healthy, while optimizing natural and human resources (FAO, 2010).
Gustafson et al6 (2016) identified food nutrient adequacy, ecosystem stability, food affordability and availability, sociocultural well-being, food safety, resilience, and waste and loss reduction as the critical sustainable food system assessment criteria and provided a number of existing indicators that could be applied to each of them. This framework, or a similar one, has many advantages. It is critically important that decisions about food be made with enough information to achieve the desired outcome.
The dairy sector's recent contributions to sustainable food systems research have included a peer-reviewed life cycle assessment of all of the activities and environmental impacts that it takes to produce milk, from “cradle to grave.” It is evaluating protein quality in addition to protein quantity to measure food production efficiency, and it has used disability-adjusted life-years to assess the impacts of dairy food production and consumption on human quality of life.7 It uses these data to establish benchmarks for continued improvements. For example, without quantifying dairy's already low carbon footprint relative to other sectors in this country (approximately 2% of total US emissions, determined by the life cycle assessment), it would have been unable to set and measure progress toward its voluntary goal of a 25% reduction in emissions intensity by 2020.8 The dairy sector is also engaged in research on human health, animal welfare, and the economic considerations of dairy production and consumption.
A responsible food system discussion should also include perspectives on trends and future opportunities to improve environmental performance, rather than relying on a snapshot of a specific moment in time. For example, a recent FAO report found that, although global milk production increased 30% between 2005 and 2015, net emissions only increased by approximately half that amount.9 Clearly, significant efficiency gains have been made. In fact, the same report found that there had been a net decrease of approximately 5% in dairy greenhouse gas (GHG) emissions in North America during that time while still accompanied by a production increase. A simple comparison of the emissions of one category of food to another for a particular year would lose this nuance. Before advocating for massive, rapid, and potentially disruptive shifts in global dietary patterns, we should understand how the impacts of producing the foods consumed today have and are expected to change.
There is more work to be done; in the nutritional sciences, studies need to move beyond simply examining energy or macronutrient content of diets and start including overall nutritional quality when comparing the environmental impacts of different diet/food choices. Furthermore, behavior should be considered because some simulated dietary changes might not be considered reasonable or realistic. Better quality data sets for assessing the cost and environmental impact of diets are needed to look at this important issue holistically and accurately. Incidence or prevention of noncommunicable diseases would be an excellent metric to factor into the assessment of sustainable diets. An FAO report on milk and dairy products in human nutrition found that “milk plays a key role in treating undernutrition both in industrialized countries and in developing countries.”10 This is due to a variety of factors, including the full complement of nutrients available in milk, the availability of dairy products, the digestibility and absorbability of individual nutrients such as calcium, and measures of protein quality. However, dietary guidance regarding milk and dairy foods should be appropriate to specific countries, populations, and/or food systems and recognize potential consequences of overconsumption as well as considerations involving food safety, supply chain reliability, affordability, and cultural acceptability.
In addition, economic considerations, another of the “4 domains” of sustainable diets (along with nutrition, society, and the environment), cannot be forgotten. Failing to model the impacts of large-scale dietary and agricultural shifts on both consumers and food producers would dramatically weaken our ability to make informed decisions on global nutrition.11 We know, for example, that dairy foods are some of the most affordable sources of critical macronutrients and micronutrients domestically.12,13 Although they are less affordable in low- or some middle-income regions than in the United States, dairy consumption is predicted to increase dramatically as nations continue to develop and expand the sector and its economic impact.14 It is important to understand the effects that identifying and producing alternate sources of this nutrition would have on the livelihoods of the millions of farmers who would be affected.
There are important and urgent issues still to be addressed in the current global food system, including animal agriculture. The Intergovernmental Panel on Climate Change found that “agriculture, forestry and other land use activities accounted for around 13% of CO2, 44% of methane (CH4), and 82% of nitrous oxide (N2O) emissions from human activities globally during 2007–2016, representing 23% of total net anthropogenic emissions (those coming from human activity) of GHGs” and that livestock are responsible for more than half of the N2O emissions and a large percentage of agriculture's methane.15 The FAO estimated that, on a commodity basis, cattle milk is responsible for 20% of the global agricultural sector's GHG output. The amounts of water used and land occupied by livestock are significant as well. Livestock occupy more than 2 billion hectares of pasture and grasslands around the world, of which approximately 700 million hectares (roughly one-third) could be used as cropland.16 Efficiency gains must continue to be made throughout the dairy sector, domestically and globally. Domestically, the US dairy industry is exploring gains in performance through the creation of secondary farm products, such as renewable energy and nonsynthetic fertilizers, from manure, new cow diet formulations and novel feed sources to support milk production at lower environmental costs, and sequestering carbon in the farmlands it occupies.
However, the same FAO report also identified livestock as a means of enhancing the adaptive capacity of rural communities globally, including some of the most vulnerable. The world of food and nutrition is not simple. Solutions to the looming environmental and human health challenges will not be found by reductionist thinking. We need science and data that will allow us to understand the important variables and model the tradeoffs between nutrition, environment, dietary choices, and economics as we plan the evolution of our food systems. Focusing on the environmental footprint of food as the sole standard for sustainable food patterns may run counter to achieving human nutritional needs, and that is not sustainable. Instead, an integrated systems approach that standardizes and incorporates data covering nutrition, economics, environment, and the full range of social concerns of a food system must be developed.
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