1. Introduction

Despite the growing emphasis on the need for integrating EJ and sustainability, at least conceptually ^[1][2][3][8,9,10], there remains some sustainability scholarship that focuses on conservation-based or deep ecology concepts that lack attention to the social, economic and political contexts, including justice and equity issues ^[4][5][6][7][11,12,13,14]. Fortunately, much progress towards more interdisciplinary and systems-based approaches to studying sustainability issues have emerged. For example, the field of earth systems science offers a way for natural scientists to work across disciplines to build a more unified understanding of our planet, including the impact of human activities on global change ^[8][15]. Additionally, from social science theory, ‘ecological modernization’ provides a framework for analyzing the institutional reforms necessary for reducing human impacts on our environmental systems or natural resources ^[9][16]. Despite these increasing opportunities for more meaningful, cross disciplinary scholarship, the consideration of justice and equity in sustainability scholarship remains a challenge, particularly in practice or in application. This is a bit counterintuitive, given that the frequently quoted definition of sustainable development in the 1987 Brundtland Report is ‘development that meets the needs of the present without compromising the ability of future generations to meet their own needs’ ^[10][17] (p. 43). This definition explicitly calls for intergenerational justice as a central and underlying principle of sustainability. On the other hand, intragenerational equity considerations, although arguably important, remains often under-developed in the general concept of sustainability.

This lack of attention to the justice related elements of sustainability is particularly evident in sustainability education programs. For example, a recent study examining new sustainability requirements for undergraduates attending the University of Vermont found that although sustainability courses are found throughout many different disciplines, most of which address all three pillars of sustainability, issues of EJ were only addressed in 17% of those courses in science, technology and math ^[11][27]. Another study on sustainability curriculum assessment at the University of Wisconsin–River Falls found, among other things, that many of the sustainability courses in the program favored environmental themes alone, with little or no consideration for EJ ^[12][28].

Nevertheless, we see an increase in the incorporation of EJ in sustainability scholarship, namely coining the term ‘just sustainability’ which emphasizes the need for a meaningful integration of sustainability and EJ concepts ^[2][13][9,29]. In particular, this concept adjusts the widely used Brundtland definition of sustainable development to the following, “The need to ensure a better quality of life for all, now and into the future, in a just and equitable manner, whilst living within the limits of supporting ecosystems” ^[14][30] (p 5). One challenge for this integration of EJ with sustainability is the greater focus on and allocation of funding for research on the scientific and/or technological aspects of sustainability, yet the major barriers to achieving and practicing sustainability remain in the social or cultural domains of the issue. For example, Keivani (2010) ^[15][31] discusses key challenges for urban sustainability across the globe, stemming from poor governance and the resulting intra-urban social inequities characterized by exclusion, poverty, and crime. Moreover, numerous scholars have made the case that it is our cultural values and worldviews that drive people to accept or reject the science of climate change, and that without building a social consensus around climate as an urgent issue to address the problem will go largely unresolved ^[16][17][18][32,33,34].

To help address this relative lack of attention to the social pillar of sustainability, and more specifically explore the integration of EJ and sustainability in the academic literature, we completed a literature review. While previous work has already outlined the need for the integration of EJ and just sustainability and offers comparisons and synergies between the two movements ^{[1][2][3][19]}[8,9,10,35], the key contribution of this paper is to explore the integration of these movements in actual scholarly practice within the US. To accomplish this, we conducted a literature review of scholarship in the EJ and just sustainability space published between 1990–2020. While we acknowledge that studies exist that investigate the integration of sustainability and EJ using other methodologies ^[17][18][19][33,34,35], we are not aware of any literature reviews on this particular topic. The primary objectives of this review were to (1) identify common themes for which EJ and sustainability are being integrated, (2) qualitatively assess the progression of the integration of these important movements, and (3) inform research gaps that exist in this area. The overarching goal is to help guide and inform sustainability scholars and changemakers seeking to aid in the transformation of the sustainability field to more broadly address social needs and welfare in balance with important environmental concerns.

2. Development and Findings

Twenty articles in our review focused on sustainable development and planning, particularly how to better integrate methods of addressing EJ issues into planning for sustainable development. This was the largest category. Interestingly, most of the articles found in our second search on just sustainability were placed here. Although some of the papers already discussed in our review may have implications for planning, these papers are specifically framed as useful for urban development and strategic sustainability initiatives. We further divided these articles into subcategories, including the following: two primarily conceptual pieces that discuss the integration of EJ and sustainable development but also include examples or cases to support the conceptual contributions; four articles that offer a review of sustainability planning documents and/or websites looking for evidence of EJ integration; nine papers that discuss the integration of EJ and sustainability through specific types of greening projects (i.e., green infrastructure, wind energy, bike paths, urban forestry, etc.); and finally we have a subcategory with five papers that claim to offer effective frameworks or models of just sustainability projects.

First, examining the conceptual relationship between sustainability and justice, Krueger and Savage (2007) ^[20][67] argue that despite some excellent work on the concept of just sustainability, current constructions of sustainable development are inadequate to capture the broad array of social and economic issues found in the city-region. In particular, the authors emphasize the lack of consideration for economic development concepts in urban sustainability, which tend to be focused on environmental problems. The authors provide an example case study of a hospital privatization process in Boston, helping to illustrate the consequences of this socio-economic inadequacy of sustainable development.

In terms of promoting EJ in sustainability planning, the following four articles examine sustainability websites and/or plans, looking for evidence of integration between EJ and sustainability. Each emphasizes the lack of attention to justice and equity concerns.

In general, our literature review revealed a wide range of how well EJ and sustainability concepts were integrated in academic scholarship. We found many case studies where equity and justice considerations were being considered explicitly in sustainable development projects or played a central or underlying component of the planning process. However, some of the studies only refer to EJ issues with brief mentions of sustainability and others are more heavily focused on sustainability related initiatives, with scant attention to EJ considerations. For example, the Roman and colleagues (2017) case study, which focuses on tree cover on an urban college campus, briefly refers to the importance of the inclusion of diverse perspectives in the planning process for incorporating EJ considerations in tree planting initiatives ^[21][77]. On the other end of the spectrum, the Brady and Monani (2021) paper explicitly utilizes just sustainability principles to analyze case studies of wind energy projects on tribal lands, providing lessons learned for incorporating just sustainability considerations in sustainability initiatives much more broadly ^[22][74]. In the former, justice is a minor consideration, in the latter it is a primary focus and goal of the paper.

3. Conclusions

Despite much effort and focus on the concept of just sustainability and many scholars calling for better integration of EJ issues and sustainability, our literature review suggests that current constructions of environmental sustainability and sustainable development remain inadequate to meaningfully do so consistently. Our literature review revealed many examples where the concepts are beginning to come along with mixed success in practice. Each case study and paper show a variety of methods for approaching the integration, making it challenging to understand and develop best practices on one hand, while at the same time showing promise for successful integration of EJ and sustainability for different types of sustainability scholars. Still, much of this evidence points to barriers in strategically integrating justice and equity concerns into sustainability scholarship and research, despite growing theoretical guidance and strong willingness in many cases to do so.

Regardless of the variety of approaches and pathways that the reviewed scholarship revealed for integrating EJ and sustainability, ultimately, there is a consensus about the importance of empowering stakeholders and communities to be a part of decision-making, sustainability planning, and sustainability scholarship to promote more just and equitable outcomes. The authors view this emphasis as a call for more sustainability scholars who seek to meaningfully integrate justice and equity considerations into their work to do so through community-engaged scholarship. Although a wealth of information has been published on this topic (e.g., ^[23][90]), the basic concept is to remove barriers between academic scholarship and more practical research and knowledge for greater social impact. This often involves collaborative work with communities to address jointly defined goals and interests for societal impact and is considered critical to sustainability practice in general ^{[23][24][25][26]}[90,91,92,93]. While we acknowledge that much local and place-based sustainability work already engages with community stakeholders on a variety of topics, considerations of EJ may require an extension of existing stakeholder engagement efforts focused on including representatives from populations where injustices have occurred and/or organizations whose missions are related to local EJ or broader social equity missions. Even if the focus of sustainability work and/or planning centers on other sustainability goals, such as climate change mitigation or the greening of society, the inclusion of these voices and perspectives can help prevent unintended justice related consequences of well-intentioned initiatives. Without this type of engaged-scholarship, we argue that the meaningful integration of EJ considerations with sustainability science will remain disjointed and lacking in academic scholarship.