Food systems—in particular, livestock production—are key drivers of environmental change. Here, we compare the contributions of the global livestock sector in 2000 with estimated contributions of this sector in 2050 to three important environmental concerns: climate change, reactive nitrogen mobilization, and appropriation of plant biomass at planetary scales. Because environmental sustainability ultimately requires that human activities as a whole respect critical thresholds in each of these domains, we quantify the extent to which current and future livestock production contributes to published estimates of sustainability thresholds at projected production levels and under several alternative endpoint scenarios intended to illustrate the potential range of impacts associated with dietary choice. We suggest that, by 2050, the livestock sector alone may either occupy the majority of, or significantly overshoot, recently published estimates of humanity’s “safe operating space” in each of these domains. In light of the magnitude of estimated impacts relative to these proposed (albeit uncertain) sustainability boundary conditions, we suggest that reining in growth of this sector should be prioritized in environmental governance.

The relationships between energy use in food systems, food system productivity, and energy resource constraints are complex. Moreover, ongoing changes in food production and consumption norms concurrent with urbanization, globalization, and demographic changes underscore the importance of energy use in food systems as a food security concern. Here, we review the current state of knowledge with respect to the energy intensity of agriculture and food systems. We highlight key drivers and trends in food system energy use along with opportunities for and constraints on improved efficiencies. In particular, we point toward a current dearth of research with respect to the energy performance of food systems in developing countries and provide a cautionary note vis-à-vis increasing food system energy dependencies in the light of energy price volatility and concerns as to long-term fossil energy availabilities.