International assessments from the Intergovernmental Panel on Climate Change and Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services and business and technology innovations such as lab-grown and plant-based meat, as well as many consumer diet trends, can all be traced to studies that identify undesirable impacts of certain food systems. Yet the evidence underpinning many widely touted recommendations about what to grow and eat is remarkably sparse and generally biased.
We know that not all food is created equal in terms of environmental impact (1⇓–3). However, most past research has focused on only a few key foods (e.g., beef and staple crops) and only a few environmental stressors (particularly greenhouse gas emissions). In addition, these studies tend to be confined to a few countries, and many nations suffer from poor knowledge transfer between the scientific community and the public. Even the most wide-ranging assessments made to date (2, 4, 5) contain significant gaps (Fig. 1). These biases arise, first, because substantial portions of the global food system are inaccurately or insufficiently reported or effectively “hidden” from standard statistics (e.g., inland and small-scale fisheries, bushmeat, backyard farming) and, second, because of an incomplete knowledge of the suite of environmental impacts and how these propagate through the many linkages among food systems.
The web of food impacts and interactions are challenging to map, let alone fully assess. Yet characterizing these linkages is essential to understand the true cumulative impact of food production (2, 3). Without doing so, society risks unknowingly exceeding regional, or even global, environmental boundaries or missing opportunities to steer food consumption and policy toward more sustainable foods and practices. Furthermore, gaps in assessments are unevenly distributed. For example, in developing regions with rapidly growing human populations, unassessed foods underpin the nutrition of millions and provide essential sources of protein for more than three billion people (3, 6, 7). It is hard to imagine developing science-based food policy for regions where so many of the common foods have never been assessed in terms of environmental impacts.
Two major gaps in our understanding—substantial holes in food assessment studies and the nearly complete absence of linkages among foods in these assessments—limit our ability to link environmental impacts to food security. We show how this lack of understanding undermines decision makers’ capacity to develop policies ensuring the planet can sustainably meet future human food demands. We recommend tackling these gaps by improving the environmental impact assessment of food production and supporting the development of effective, integrative food policy.