Significance: This study uses data on ∼93 million individual homes to perform the most comprehensive study of greenhouse gases from residential energy use in the United States. We provide nationwide rankings of carbon intensity of homes in states and ZIP codes and offer correlations between affluence, floor space, and emissions. Scenarios demonstrate this sector cannot achieve the Paris Agreement 2050 target by decarbonizing electricity production alone. Meeting this target will also necessitate a broad portfolio of zero emission energy solutions and behavioral change associated with housing preferences. To support policy, we estimate the reductions in floor space and increases in density needed to build low-carbon communities.

Essential for society to function, the production and consumption of food, energy, and water (FEW) are deeply intertwined, leading to calls for a nexus approach to understand and manage the complex tradeoffs and cascading effects. What research exists to date on this FEW nexus? How have scholars conceptualized these interactions at the urban scale? What are some promising approaches? Where are the research gaps? To answer these questions, we conducted a quantitative review of the academic literature on the FEW nexus (1399 publications) over more than four decades (1973–2017), followed by in-depth analysis of the most influential papers using an evaluation matrix that examined four components: 1) modeling approach; 2) scale; 3) nexus ‘trigger’; and 4) governance and policy. Scholars in the fields of environmental science predominated, while social science domains were under-represented. Most papers used quantitative rather than qualitative approaches, especially integrated assessment and systems dynamics modeling although spatial scale was generally recognized, explicit consideration of multi-scalar interactions was limited. Issues of institutional structure, governance, equity, resource access, and behavior were also underdeveloped. Bibliometric analysis of this literature revealed six distinct research communities, including a nascent urban FEW community. We replicated the analysis for this urban group, finding it to be just emerging (80% of papers have been published since 2010) and dominated by scholars in industrial ecology. These scholars focus on quantifying FEW flows of the urban metabolism in isolation rather than as a nexus, largely ignoring the political and socio-economic factors shaping these flows. We propose the urban FEW metabolism as a boundary object to draw in diverse scholarly and practitioner communities. This will advance research on complex FEW systems in four key areas: (1) integration of heterogeneous models and approaches; (2) scalar linkages between urban consumption and trans-boundary resource flows; (3) how actors and institutions shape resource access, distribution and use; and (4) co-production of knowledge with stakeholders.

Despite extensive literature on the socio-cultural services of urban open spaces, the role of food-producing spaces has not received sufficient attention. This hampers advocacy for preserving and growing urban agricultural activities, often dismissed on justifications that their contributions to overall food supply are negligible. To understand how the social benefits of urban agriculture have been measured, we conducted a systematic review of 272 peer-reviewed publications, which drew on insights from urban agriculture sites in 57 different countries. Through content analysis, we investigated socio-cultural benefits in four spheres: engaged and cohesive communities, health and well-being, economic opportunities, and education. The analysis revealed growth in research on the social impacts of gardens and farms, with most studies measuring the effects on community cohesion and engagement, followed by increased availability and consumption of fruits and vegetables associated with reduced food insecurity and better health. Fewer studies assessed the impact of urban farming on educational and economic outcomes. Quantifying the multiple ways in which urban agriculture provides benefits to people will empower planners and the private sector to justify future investments. These findings are also informative for research theorizing cities as socio-ecological systems and broader efforts to measure the benefits of urban agriculture, in its many forms.