Sustainability as an Emerging Paradigm in Universities

Abstract

This article aims to review the perspective of sustainability adoption in universities through two dimensions: firstly, from the educational and research process, and second, from their global positioning in terms of the performance of their university campus. For this purpose, a bibliometric analysis was carried out, referring to publications dating from 2006 to 2020, using the terms “Sustainability, green universities and curricular sustainability” as search keywords. In addition, an analysis of eight global university rankings was made, gathering information from their official websites on their evaluation fields, indicators, and volume of Ibero–American universities cataloged. The result is that, since 2007, the number of publications on this topic has increased, showing that the participation of Latin American in publications is very low (3.69%). Furthermore, only 12% of Latin American universities are included in world rankings. Sustainability has hardly been integrated into university academic programs; likewise, it is observed that the traditional world ranking of universities mainly take into account factors related to teaching and research, without considering criteria related to sustainability. Moreover, it is essential to develop policies that encourage universities to develop sustainability strategies in their academic and institutional processes in general, as well as in the global university evaluation systems, in order to value sustainability adequately in both in academics, research and institutional performance.

1. Introduction

Sustainability has become a process that allows the use of resources, contributing to economic growth and environmental protection. Therefore, it is becoming a fundamental element for universities, as it is a development strategy that benefits all generations.

Thus, taking into account that factors such as consumerism, overexploitation of natural resources, pollution, and the environmental crisis that is manifested in the world, it is necessary to undertake a series of actions to care, reverse or mitigate the problems that have been generated over the years; institutions are needed to strengthen productive activities through the teaching of ecologically efficient processes, where a fair balance of the social, ecological, economic and sociocultural spheres is achieved.

This concept is therefore related to the satisfaction of all needs that seek a balance between economic growth, social welfare, and environmental protection, generating the need to establish a relationship between society, economy, and nature, which has led to the implementation of measures that are reinforced by education to contribute to systemic change from very early stages such as early childhood education to higher education at the university level [1].

Universities, being the training center for future professionals and agents of change, have the responsibility to provide society with professionals who, in the exercise of their profession, meet our current needs without compromising the possibilities of future generations to respond to theirs.

Recently, indicators have been established to measure and evaluate environmental and sustainability aspects, which are key elements for the training and acquisition of knowledge necessary for the implementation of sustainability policies [2].

Authors such as Alshuwaikhat et al. [3] argue that universities are promoters of the culture of sustainability in society, representing models of sustainable development, in which innovation is an indispensable and decisive factor for the use of resources without damaging the social, environmental, and productive environment.

Thus, their performance has been measured through Global University Rankings, motivated by the demand for information regarding the quality of their processes, allowing a comparison between them. Usually, the parameters or indicators applied by these rankings are related to research activity: citations, number of publications, number of researchers, number of graduates with Nobel prizes, Fields medals, academic reputation, the ratio of professors per number of students, and academic reputation; however, Brusca et al. [4], indicate that university sustainability reports are still in the primary stages and few institutions publish them.

Many authors have worked on the topic of rankings, among them the authors listed in the table below (

Table 1. Rankings Literature Review.

Authors	Evidence
Cuartas et al. [5]	They indicate that recent measures of science present a debate on how the system should be measured in terms of evaluating scientific production. It is therefore important to consider concepts that describe the development of science, in terms of visibility, community building, and contribution to society. It is important to mention that institutions should propose changes in the form of evaluation of scientific production, which involves putting pressure on countries’ public policies and developing models that help governments to order their priorities in terms of science and technology policy.
Uribe-Tirado et al. [6]	In their work, they indiquate that it is important to establish a model to identify the degree of connection of universities with their environment, for which it is relevant to identify the impact and visibility of researchers.
Freidenfelds et al. [7]	They indicate that the analysis of global warming engages all members of society to jointly find ways and solutions to problems such as the use of resources, the impacts of transportation, waste management, among others, and a call is therefore made to HEIs, as organizations where tomorrow’s leaders are prepared, to actively participate in this issue.
Atici et al. [8]	It establishes that the role of HEIs is a supportive leadership and goes hand in hand with improving the environmental infrastructure of their campuses, as well as updating curricula to include environment and sustainability courses. Some of the results of this work indicate that being green has an impact on university rankings, and environmental sustainability generates a competitive advantage for universities.
Wu [9]	It indicates that sustainability has become a relevant aspect for human beings in their daily activities, and that it is important to turn a university into an environmentally friendly campus in an efficient way.
Dagiliūtė et al. [10]	Higher Education Institutions, generate a positive impact on society and play an important role in raising awareness about sustainability, as green universities contribute are expected to contribute more to the performance of sustainability, the so-called green students agree that the university does generate this impact, but this should be stated through activities and information campaigns that contribute to sustainability in a more comprehensive way.
Puertas & Marti. [11]	The authors propose a new index for quantifying universities’ contribution to sustainability, which ranks campuses accordingly and evaluates specific aspects of their institutionalism related to their policies. As a result of their measurements with this new index, they point out that universities require greater efforts to improve their performance in environmental variables, regarding energy use, water and waste treatment.

Source: Own elaboration.

).

Alhaddi [12] indicates that the integration of different aspects in decisions that guarantee environmental sustainability and human welfare is a tool that transcends to promote innovation and environmental sustainability as well as economic and social spheres

According to Pérez [13], educational institutions have a great impact on the issue of environmental sustainability. This includes the improvement of infrastructures on their campus, turning it into spaces that are respectful of the environment and updating of study plans so that they integrate environment and sustainability.

Sustainability and sustainable development are controversial concepts in academic and public spheres, with multiple meanings and diverse interpretations [14]. Regardless, there is broad consensus in differentiating three interdependent dimensions of sustainability that are fundamental to the growth of people and societies: environmental, economic, and social [15]. These dimensions cannot be conceived as competing with each other, and advances in one cannot compensate for regressions in another. Therefore, education for sustainability must be based on experiential, systemic, and interdisciplinary learning [16] and must be oriented toward the development of conscious citizens.

In the 2030 Agenda, education is shown throughout the document as a necessary precondition for achieving the Sustainable Development Goals (SDGs), but Goal 4, specifically for education, is particularly relevant, where it states: “Ensure that all learners acquire the knowledge and skills necessary to promote sustainable development, including through Education for Sustainable Development and the adoption of sustainable lifestyles, human rights, gender equality, promotion of a culture of peace and non-violence, global citizenship, and appreciation of cultural diversity and the contribution of culture to sustainable development, among other means”.

The objective of the research is to examine the perspective of sustainability adoption in universities from two dimensions: firstly, from the educational process, and second, from their global positioning in terms of the performance of their university campus. The article begins by presenting a conceptual framework of the role of the University in a sustainable society; the second part identifies sustainability of the curriculum; and then describe the methodology used for doing a bibliometric analysis of scientific articles on sustainability and the collection of data from eight (8) global university rankings regarding Ibero–American higher education institutions, in order to describe the performance of universities in the adoption, implementation, and evaluation of sustainability.

2. The Role of the University in a Sustainable Society

The university has a fundamental role in the process of development and improvement of individuals and societies, so it has the obligation to include in its curricula concepts such as sustainability, a concept that has been worked since the seventies, when calls for attention to unlimited growth arose, generating reflections on the obligation to take measures for the conservation of our planet, due to the effects that the economic crisis has caused to the environment [17,18].

It is very valuable for higher education institutions to promote in their students the active participation within sustainable programs that generate activities in service to the community. Moreover, it is important to indicate that research provides information of the real needs of society to meet the fulfillment of the same, generating the reorganization of their curricula that allow students to train in other aspects, so that it fulfills the true role that is to incorporate to society professionals prepared to solve current problems [19].

In the study conducted by Tamrat, [20] whose objective is to measure the relationship between sustainability practices in the College of Open and Distance Learning (CODL) at St. Mary’s University, Ethiopia, the authors indicate that the institution has a limited involvement in issues related to sustainability despite the policies that have been established by this educational institution. The patterns of involvement are located in some courses on sustainability issues and thus there is a gap in relation to research and community service, which is increasingly neglected.

Hence, there is concern on the part of countries and companies to implement activities that promote the development of processes for the use of resources [20], to generate an adequate distribution of them [21] respecting the conditions in which they are found in the environment, their use, the endogenous activities that derive from them and the actors that participate in their use [22], to become in this way elements that are incorporated into the concept of sustainability.

Sustainability is defined as a dynamic process that involves aspects that promote the economy in the long term, through the conception of healthy and fair environments [23]. Gallopín [24] defines it as a concept in which several variables converge, which facilitates its systemic measurement, which can be represented by an evaluation as a decreasing function of the outputs or products of the system analyzed.

Other authors, such as Morelli [25] and Lindsey [26] consider that sustainability requires the sum of various activities that contribute to future benefits, in which the economic, social, and environmental dimensions converge [27].

In this sense, it is important to identify the factors that facilitate the development of sustainability programs in the institutions and particularly, the alliances that can be achieved for their implementation, as well as the establishment of indicators that allow measuring their degree and level of compliance.

At the global level, actions and programs have been established to link actions to promote the integration of the actors that participate in the economies. The United Nations, for example, used the concept of “green economy” in March 2009 in the Global Green New Deal [28]. Its mention was made after the need to propose policies that allow generating economic recovery and sustainability of countries; hence, States are asked to allocate resources that stimulate the development of a culture focused on three objectives: (i) economic recovery; (ii) poverty elimination; and (iii) reduction of carbon emissions and ecosystem degradation; and proposed a framework for ecological stimulus programs, as well as national and international support policies.

In the case of the Organization for Economic Cooperation and Development (OECD), an intergovernmental international organization made up of 37 states whose objective is to coordinate their economic and social policies, the phrase “green growth” was used in the declaration of the ministers of the Green Growth Group 21], as a factor for the incorporation of measures aimed at generating sustainability in the processes developed in the economies.

Similarly, the World Bank formalized the concept of “green and inclusive growth” in its Annual Report [29], which includes sustainable growth from an environmental care perspective and incorporating three characteristics: (i) cost efficiency, (ii) innocuousness referring to the use of non-polluting energies and (iii) resilience by appreciating the role of natural capital in the prevention of natural disasters [30].

Therefore, the case of universities is analyzed, since they are the fundamental basis of academic processes, in which not only the transmission of knowledge should be conceived, but also the implementation of actions that generate economic, environmental, and social impact.

2.1. Sustainability in Universities

Universities must maintain constant contact with society, get involved in social issues, identify trends, and put knowledge into practice in order to achieve sustainability of human systems.

Tilbury [31] states that higher education institutions are obliged to have a dynamic nature through which sustainable innovative processes can be established so that each of the curricula aims to be oriented to real life through relationships with different industries or other institutions.

According to Rieckmann [32], the implementation of sustainability continues to be a great challenge for everyone, because competencies must be generated and must be developed by each of the academic programs and require methodological planning for effective learning in the student through educators and administrative staff, recognizing the importance of a common framework of different competencies that are constantly interrelated.

Thus, universities, which are institutions of higher education, are focused on training professionals in different areas of knowledge or work, through curricula, criteria, and comprehensive information; however, they have a great challenge in the face of sustainability [33].

Unfortunately, the rare existence of training on the subject of sustainability for university teachers has been identified, and because of this, there is no real knowledge in the university community about the concepts of sustainability and curricular sustainability. Moreover, the institutional commitment is totally limited and has been difficult to integrate, bringing with it difficulties in putting into practice the theory that is taught in the classroom, trying to make learning didactic for contents, methodologies and evaluation systems [34,35].

In October 1990, in France, a meeting was held between 22 universities, with the aim of reaching an agreement to transfer the necessary bases for the generation of sustainable programs that would lead to solving problems related to pollution, unbalanced production and consumption trends, and poverty [36]. From its results, the Talloires Declaration (1990) was born, which highlights the role of universities [37] as the axis of education, policies, research, and implementation of activities that promote sustainability.

In this sense, universities have incorporated contents and competencies to be developed in their curricula, in order to generate academic programs highly oriented to sustainability [38], without neglecting the generation of activities related to the changes that markets are permanently registering as a result of globalization.

In this way, elements are defined allowing to adapt the design of the curricula, and also the operational and institutional aspects of their activities [39], which are based on quality, transparency in their processes, and the way in which they submit their reports [40].

The measures they have begun to implement address issues focused on sustainability. According to Figueredo and Tsarenko [40], this is supported by activities related to communication, considering that it is an influential process in all the actors that participate in the markets.

In 2010, the University of Indonesia established a Rankin of green universities to evaluate the responsibility and commitment of these institutions in relation to sustainability [41] and has been working on this objective since 2006 [42].

The process of sustainability in the university is not considered simple and involves a deep analysis of the educational model, with the aim of creating a strategy to make it more effective, and promoting changes based on the creation of culture as a model for sustainable development [3].

This leads to encompassing substantive functions of higher education institutions, which generate leading professionals, from their profiles and tasks, in such a way that sustainability in future generations and contributions in the processes of building sustainable cities are important [43,44].

The mentioned commitments should support the involvement in the quality and importance of education for sustainability and the need to value aspects such as social, economic, and political aspects of sustainable development [45]; it is also important to prioritize research, dissemination, partnership, campus operations [46], programs and micro curricula, which allow introducing contents, methodologies, and practices that support teaching and training in competencies related to sustainability, which are specified in the profiles of future professionals.

Countries need sustainable universities for their economic and social development [10]; it is necessary to generate processes of training, innovation, research, and problem-solving, which are based on the knowledge of the city, the academy is an engine for evolution, as a generator and executor of projects.

In view of the above, it is sought that future generations are integrated by responsible citizens and leaders, with priority in social awareness, in such a way that they perceive, witness, and meet the needs that arise, avoiding compromising the ability of future generations to meet their own needs [11].

According to the United Nations Environment Programme (UNEP), a sustainable university is one whose activities are ecologically, socially and culturally equitable, and economically sustainable. To this purpose, it follows some fundamental principles as presented in Figure 1.

Two conceptual aspects are clearly highlighted regarding the role of the university in building sustainability. The first considers the issue of education as a fundamental practice for Higher Education Institutions to contribute to the qualification of their graduates and future decision makers so that they include the concern for sustainability in their professional practices. The second focuses on the positioning and behavior of these institutions in the implementation of sustainability in their university campuses. In other words, the vision of Education for Sustainable Development is broader and more comprehensive than that referring simply to theoretical discussion and awareness-raising based on data on sustainable development. Education for Sustainable Development encompasses both the theoretical side and the more practical action through policies, programs, processes, and operations on the university campus.

2.2. Sustainability of the Curriculum

In the coming decades, sustainability will become an imperative requirement for global society to address environmental challenges that can be seen in rising sea levels, increasing global temperatures, deforestation, loss of biodiversity, and decreasing availability of natural resources. If certain approximate threshold levels are exceeded, such environmental changes would cause serious disruptions to ecosystems, society, and economies. Because, to a large extent, these changes are the result of human consumption, moving toward sustainability would likely require radical changes in the values, educational systems, and social behavior that underpin current economic paradigms, consumption patterns, and power relations [11].

Academic sustainability is collaterally related in the university curriculum to the environment, ethical behavior, poverty alleviation, gender equality, health promotion, human rights, cultural diversity, peace, responsible production, and consumption.

Universities are increasingly committed to the transmission of knowledge related to citizenship [47,48], which is considered the legal status that recognizes individuals as members of an egalitarian political community and is constituted by four dimensions: rights, duties or obligations, participation in the public sphere and belonging to a State—Nation [49].

The concept of Education for Sustainable Development (ESD) has evolved to respond to the need for intervention in order to stop the deterioration of the natural environment and, as a consequence, to stop the impact generated by anthropic activity in recent decades [50].

Linked to the analysis of the concept itself, this has been shaped in the way and the moment of incorporating it in the formative process of people. Indeed, a fundamental problem of higher education in the present century is to train students in the development of competencies for sustainability that will enable them to prevent and solve socio-environmental problems, as well as to carry out actions based on sustainable criteria in their future professional field [50].

Therefore, there is no doubt that they must be able to:

• Understand how professional activity relates to society and the environment at the local and global level, in order to identify challenges, risks, and possible impacts.
• Generate spaces for discussion, design, definition, implementation, and evaluation of policies and actions in the public and private spheres, in such a way as to redirect society towards more sustainable development.
• Develop a professional intellect based on deontological principles and universal ethical values, which protect human rights and the socio-environmental quality of their environment.

Universities, as institutions that train future citizens and professional leaders of society, have a decisive factor in the introduction of sustainability in the curriculum of students, called curricular sustainability (CS).

The goal from CS implemented by universities or institutions of higher education in intra- and extra-curricular areas is to make correct use of natural spaces and to understand that it is a source of resources but that we should not abuse what it has to offer, furthermore, the environment and its care is totally cultural and should be taught from childhood by our home tutors, understanding that the positive environmental values should be taught and that the interests of a few should not be a priority over the general welfare in ecological matters, so we must begin to promote work from the real possibilities to be effective in improving our actions [51,52].

The idea of educating for sustainability is to have a new vision of the world, to be able to think, feel and act to enter into the ecological, economic, and social dimensions, to reach those fundamental skills to achieve a new ethic that guides people’s ability to act in solidarity and equity, understanding that we are not the only living beings in the world [53]. Different holistic and systemic approaches need to be connected to generate a policy of working together to make strategic changes in current pedagogy [26].

The Conference of Rectors of Spanish Universities (CRUE), in the sectorial commission CRUE-Sustainability, is divided into a work team focused on curricular sustainability. The work of this group has produced results; in 2012, the document “CRUE Guidelines for the introduction of sustainability in the curriculum” was ratified. Spanish universities have different areas of research on how to incorporate sustainability in the university curriculum. One of the debates is whether to include it as a subject or as a transversal subject through competences [53].

Building active and participatory citizenship is especially important during youth, when people become active protagonists of their citizenship status [54], and educational institutions, such as universities, play an important role in this [55,56].

The construction of a citizenship committed to environmental sustainability, equitable economic development, and social and intergenerational justice makes education a key area to address the transformations that sustainability implies. This aspect has been present since the first international summits on this subject, such as the United Nations Conference on the Environment in Stockholm, 1972; United Nations Conference on Environment and Development in Rio de Janeiro, 1992 [8].

The curriculum is considered one of the key elements that govern the educational process; it is where the learning necessary for the full development of each person takes shape, the idea is that through them adequate standards are achieved [57]. It should be remembered that the hidden curriculum also exists when classes do not go according to plan and begin to cover different topics with active listening on the part of the students, which teaches them a specific topic that may or may not have been prepared beforehand.

In another vein, Smith and Dollase [58] indicate that there are different pedagogical methodologies for teaching a wide range of skills that allow for the correct adaptation and creation of opportunities for concept learning, content, skills, and discoveries to be put into practice with the teacher playing the role of a coach who helps to change the focus of traditional exercises by instilling the new sustainable approach.

According to Lozano [59] there has been an increase in the integration of sustainable development (SD) into the publication techniques of higher education institutions (HEIs). Several tools have been developed to assess SD in HEIs; however, only a few have focused on curriculum assessment. Curriculum assessment can provide an overview of how courses and programs incorporate SD.

The analyses showed that (a) teaching in European courses covers many sustainability issues in a fairly good balance, with the exception of social issues which are the least addressed; (b) there are correlations between economic, environmental, social, and cross-cutting issues; (c) women tend to teach SD in a more equal way than men; (d) types of HEIs do not influence the way SD is taught, but the educational level does; and (e) some countries, in the case of this research, Italy and Spain, may show more interest, although the average results tended to be lower than those of others, such as Sweden, the UK and the Netherlands. Curriculum assessment provides a diagnosis of SD incorporation and the factors affecting it.

This can help educators improve their courses and provide students with better SD knowledge and skills. Bautista-Cerro and Díaz [60] found in an in-depth analysis of the reports of the UNED undergraduate courses a huge inequality in the presence and treatment of sustainability in each course, being relevant to the lack of citations referring to sustainability in the sections of competence and learning outcomes.

The main functions that these indicators should have are to diagnose sustainability, monitor our actions, evaluate university sustainability processes, communicate results, and raise awareness in the university community. To a large extent, this means that different indicators will be used for each of these functions and these indicators should be reflected in the Global University rankings that evaluate their performance.

3. Methodology

In order to develop the objective proposed in this article on the adoption of sustainability in universities, an analysis is made from two dimensions: First, from the educational and research process, and second, from its global positioning in terms of the performance of its university campus. The first dimension incorporates sustainability in the curricula and research is incorporated through scientific production on sustainability. Therefore, a historical review was conducted on the progress on the issues of sustainability, green universities, and curricular sustainability between 2006 and 2020, through a descriptive bibliometric analysis to synthesize and understand the evolution of these concepts in specific fields of knowledge.

For this analysis, publications were examined between 2006 and 2020, which address specific topics directly related to the subject. The works are included in the bibliographic database Scopus, using search filters composed of the terms “Sustainability, green universities and curricular sustainability”, which could be placed in the title, optionally in the abstract and keywords. The search was conducted in Spanish, English, French, Italian and Portuguese, and was limited to documents of the following types: conference papers, articles, book chapters, reviews, and books. The search resulted in 1615 documents that were downloaded from Scopus and analyzed using the Bibliometrix^® package of R, which facilitated the elaboration of schemas to feed the research and the analysis of the evolution of the concepts studied [61].

Regarding the performance of sustainability in its university campus, the institutional perspective is reviewed, recognizing the performance of the university as an organization in the implementation of sustainability through green systems of global evaluation; and secondly from the integral perspective, considering criteria of the traditional academic systems of global evaluation of universities. For this purpose, information is collected from eight (8) global university rankings in their official websites on the scope of their evaluations, indicators, and volume of Ibero–American universities cataloged; likewise, the incorporation of sustainability in these systems of indicators is observed and analyzed.

Each of these perspectives is described in terms of a specific area of performance, which is illustrated in Figure 2. In addition,

Table 2. Methodological summary for the development of the present paper.

Perspective on Sustainability Performance in Universities	Scope of Adoption	Research Method	Technique or Tool Analysis	Source	Filters or Criteria for Data or Content Selection
Academic	Incorporation in curricula.	Literature review	Content analysis	Papers indexed in the Scopus bibliographic base.	- Search by: Sustainability, green universities, and curriculum sustainability. - Languages: English, French, Spanish, Italian, Portuguese, and French. - Document type: conference article, scientific article, book chapter, review, and book. - Period: 2006 to 2020.
University scientific research	Publication of scientific articles.	Literature review Bibliometric analysis	Content analysis Bibliometrix® application	Papers indexed in the Scopus bibliographic base.
Institutional	Assessment as an institution by green indicator systems.	Data collection on global green university green rankings.	Descriptive statistics	- THE—Times Higher Education, University Impact Rankings. - Green Metric.	Ibero–American Universities Data compiled as of June 2021
Integral	Comprehensive evaluation of the university by traditional indicator systems.	Compilation of data from traditional global university rankings.	Descriptive statistics	- ARWU—Universities of Shanghai. - QS—World University Rankings. - Webometrics—Ranking Web of Universities. - SIR—Scimago Institutions Rankings. - SIR IBER -Ibero–American Ranking of Higher Education Institutions. - THE—Times Higher Education, World University Rankings.	Ibero–American Universities Data compiled as of June 2021

systematizes the summary of the approach of the two dimensions distributed in four perspectives to carry out this research.

Regarding the evaluation of universities, specifically considering Ibero–American universities, eight recognized rankings were selected, where the last two mentioned below are green scorers:

• ARWU- Academic Ranking of World Universities of Shanghai.
• QS World University Rankings.
• Webometrics—Ranking Web of Universities.
• SIR- Scimago Institutions Rankings.
• SIR IBER—Ibero–American Ranking of Higher Education Institutions.
• THE (Times Higher Education) World University Rankings.
• THE (Times Higher Education) University Impact Rankings.
• Green Metric.

For each ranking mentioned above, the scope of its evaluation and the indicators used are characterized and described. Likewise, the Ibero—American universities positioned according to these catalogues are quantified, considering data published as of June 2021, reviewing the evaluation results on the respective websites.

Table 2 below presents a structured presentation of the methodological aspects according to the four performance perspectives of the aforementioned universities.

4. Results

It is important to note that higher education institutions have traditionally been evaluated, as a measure of quality, by their academic performance and scientific production. In this sense, global ranking systems have been developed to evaluate their performance and determine a comparative positioning with other academic institutions at the global, regional, and national levels [62,63]. These include the SIR, QS, ARWU, Webometrics, and Ranking [64].

These rankings are heterogeneous in their indicators and do not evaluate teaching and research activities with similar weights; however, the international recognition granted and the application in studies that analyze the performance of universities has prompted these higher education institutions to design and implement actions to advance in these rankings [65].

Table 3. Evaluation parameters of recognized global university rankings.

Ranking	Institutions Evaluated	Main Scope of Evaluation	Primary Categories
Academic Ranking of World Universities of Shanghai (ARWU)	Higher Education Institutions worldwide.	Research activity and its impact-recognition for excellence in the world.	- Alumni (10%): number of students awarded the Nobel Prize or Fields Medal. - Award (20%): the number of employees awarded the Nobel Prize or Fields Medal. - HiCi (20%): number of highly cited researchers, HiCi (20%): number of highly cited researchers. - N&S (20%): number of articles published in the scientific journals Science and Nature. - PUB (20%): the number of academic papers registered in the Science Citation Index and the Social Science Citation Index. - PCP (10%): the “per capita production”, i.e., the score of all the above indicators divided by the number of full-time academics.
QS World University Rankings	Higher Education Institutions worldwide.	Academic factors, reputation and internationalization of the institution.	- Academic reputation (40%). - Employer reputation (10%). - Faculty/student ratio (20%). - Faculty citations (20%). - Ratio of international faculty (5%). - International student ratio (5%). - Ratio of international students (5%).
Ranking Web of Universities—Webometrics	Higher Education Institutions worldwide with institutional websites accessible from the Internet.	Content published on the institutional website, and the volume, visibility and impact of this content.	- Presence (5%): number of pages of the institution’s main web domain. - Impact/Visibility (50%): number of external networks that have backlinks to the institution’s web pages. - Openness (10%): number of citations from recognized authors. - Excellence (35%): number of academic articles published in high impact international journals.
Scimago Institutions Rankings (SIR)	Higher Education Institutions worldwide with at least 100 publications registered in SCOPUS the previous year.	Scientific production registered in Scopus.	- Research (50%). - Innovation (30%). - Societal (20%).
Ibero–American Ranking of Higher Education Institutions (SIR IBER)	Ibero–American Higher Education Institutions with at least one (1) publication registered in SCOPUS in a five-year period.	Scientific production registered in Scopus.	- Research (50%). - Innovation (30%). - Societal (20%).
Times Higher Education World University Rankings	Higher Education Institutions worldwide.	Main missions of the institution: teaching, research, knowledge transfer, and international perspective.	- Teaching (30%). - Research (30%). - Citations (30%). - International Outlook (7.5%). - Industrie Income (2.5%).
Times Higher Education University Impact Rankings	Higher Education Institutions worldwide.	Relationship with the 17 Sustainable Development Goals (SDGs) of the United Nations.	- SDG 1. no poverty. - SDG 2. zero hunger. - SDG 3. good health and well-being. - SDG 4. quality education. - SDG 5. gender equality. - SDG 6. clean water and sanitation. - SDG 7. affordable and clean energy. - SDG 8. decent work and economic growth. - SDG 9. industry, innovation and infrastructure. - SDG 10. reduced inequalities. - SDG 11. sustainable cities and communities. - SDG 12. responsible consumption and production. - SDG 13. climate action. - SDG 14. life below water. - SDG 15. life on land. - SDG 16. peace, justice and strong institutions. - SDG 17. partnerships for the goals. - Overall Ranking.
Green Metric	Higher Education Institutions worldwide.	Assess current status and policies related to Green Campus and Sustainability, regarding global climate change, energy and water conservation, waste recycling, and green transportation.	- Setting and Infrastructure (SI) (15%). - Energy and Climate Change (EC) (21%). - Waste (WS) (18%). - Water (WR) (10%). - Transportation (TR) (18%). - Education and Research (ED) (18%).

describes eight rankings, including the five academic rankings mentioned above, in which can be seen that the academic performance indicators are weighted between 30 and 40%, while those related to research represent between 20 and 60% of the evaluation.

Regarding the Ibero–American and Latin American universities listed in these rankings (see Table 4), it can be seen that SIR IBER (100%) and Webometrics (33%) evaluate a higher proportion of universities compared to the other rankings, as they have more accessible criteria for universities in general to be considered within the set of institutions evaluated. It should be noted that, in these rankings, the indicators related to sustainability, taking the United Nations SDGs [66] as a reference, only those proposed by Scimago weight innovation activities in universities by 30%.

Given the emergence of an international demand to consider sustainability within the functions of organizations [67], universities have progressively joined this trend, and at the same time, there is also the emergence of university evaluation systems that consider sustainability indicators to a greater extent, to describe and weigh the overall profile of universities in this area. These are the cases of the THE University Impact Rankings and the Green Metric [68] (see Table 3 and Table 4), whose indicators evaluate especially the actions and policies regarding green campus and sustainability, noting that they report fewer universities catalogued globally, compared to the other academic rankings, not exceeding 1000 institutions each.

The Times Higher Education Impact Rankings are the only global performance tables that assess universities against the United Nations’ Sustainable Development Goals (SDGs) [69]. This uses 17 indicators, one for each SDG, and also incorporates an Overall Ranking, so that by 2020, 130 universities are identified at the Ibero–American level (17% worldwide), with Spain (32), Brazil (30), Mexico (16), Chile (13) and Colombia (11) leading this list, corresponding to 78% of the Ibero–American institutions evaluated by this ranking.

Table 4. Characterization of global rankings of recognized universities.

	Shanghai (ARWU)	QS	Webo Metrics	SIR–Scimago	SIR IBER 2020	THE World University Ranking	THE Impact Ranking	Green Metric
a Total universities ranked worldwide	1000	1069	12,001	3897	Not apply	1397	768	912
a Total Ibero–American Universities	80	133	4335	411	1747	159	130	146
%Ibero–American Universities	8%	12%	36%	11%	100%	11%	17%	16%
a Total Latin American universities	34	98	3958	317	1570	101 b	88 c	113
%Latin American Universities	3%	9%	33%	8%	90%	7%	12%	12%
a Universities Spain	40	28	265	66	105	45	32	29
a Universities in Portugal	6	7	112	28	72	13	10	4
Ranking start year	2003	2004	2004	2009	2009	2004	2019	2010
d Published years available via web	2003 to 2020	2018 to 2021	2021 (January)	2009 to 2021	2017 to 2020 b	2011 to 2021	2019 to 2021	2010 to 2020
Frequency of Publication	Annual	Annual	Biannual	Annual	Annual	Annual	Annual	Annual
a Evaluation:
Categories	6	6	4	3	3	5	18	6
Indicators				17	18	13		39
Country of publication	China	United Kingdom	Spain	Spain	Spain	United Kingdom	United Kingdom	Indonesia
Responsible entity	Jiao Tong University	Quacquarelli Symonds	CSIC	Scimago Group	Scimago Group	Inflexion Pvt. Equity Partners LLP		University of Indonesia
WebSite	[70]	[71]	[72]	[73]	[74]	[69]	[68]	[69]

^a Data for 2020. ^b Countries: Argentina, Brazil, Chile, Colombia, Costa Rica, Ecuador, Jamaica, Mexico, Puerto Rico, Peru, Uruguay, Venezuela. ^c Countries: Argentina, Brazil, Chile, Colombia, Costa Rica, Cuba, Jamaica, Mexico, Puerto Rico, Peru, Venezuela. ^d Published to date: June 2021.

Table 4. Characterization of global rankings of recognized universities.

	Shanghai (ARWU)	QS	Webo Metrics	SIR–Scimago	SIR IBER 2020	THE World University Ranking	THE Impact Ranking	Green Metric
a Total universities ranked worldwide	1000	1069	12,001	3897	Not apply	1397	768	912
a Total Ibero–American Universities	80	133	4335	411	1747	159	130	146
%Ibero–American Universities	8%	12%	36%	11%	100%	11%	17%	16%
a Total Latin American universities	34	98	3958	317	1570	101 b	88 c	113
%Latin American Universities	3%	9%	33%	8%	90%	7%	12%	12%
a Universities Spain	40	28	265	66	105	45	32	29
a Universities in Portugal	6	7	112	28	72	13	10	4
Ranking start year	2003	2004	2004	2009	2009	2004	2019	2010
d Published years available via web	2003 to 2020	2018 to 2021	2021 (January)	2009 to 2021	2017 to 2020 b	2011 to 2021	2019 to 2021	2010 to 2020
Frequency of Publication	Annual	Annual	Biannual	Annual	Annual	Annual	Annual	Annual
a Evaluation:
Categories	6	6	4	3	3	5	18	6
Indicators				17	18	13		39
Country of publication	China	United Kingdom	Spain	Spain	Spain	United Kingdom	United Kingdom	Indonesia
Responsible entity	Jiao Tong University	Quacquarelli Symonds	CSIC	Scimago Group	Scimago Group	Inflexion Pvt. Equity Partners LLP		University of Indonesia
WebSite	[70]	[71]	[72]	[73]	[74]	[69]	[68]	[69]

^a Data for 2020. ^b Countries: Argentina, Brazil, Chile, Colombia, Costa Rica, Ecuador, Jamaica, Mexico, Puerto Rico, Peru, Uruguay, Venezuela. ^c Countries: Argentina, Brazil, Chile, Colombia, Costa Rica, Cuba, Jamaica, Mexico, Puerto Rico, Peru, Venezuela. ^d Published to date: June 2021.

The Green Metric uses six specific indicators to weight the actions of universities with respect to environment and infrastructure, energy and climate change, waste, water, transportation, and education and research [70], cataloguing 146 Ibero–American institutions (16% worldwide), with the following countries standing out for the number of green universities cataloged: Colombia (47), Brazil (38), Spain (29) and Mexico (24), representing 95% of Ibero–American institutions in this ranking (Table 4).

Although the two previous global rankings present in their methodologies exclusive indicators for the weighting of sustainability actions in universities, similar percentages of Ibero–American institutions evaluated (approximately 17% with respect to the total number of universities) are observed in the cataloguing results; however, these results differ when observing the main countries of this group, so the comparative positioning of sustainability in universities, for the Ibero–American case, using these evaluation systems, should consider the scope of evaluation of each of these systems. Finally, it would be desirable that the other academic rankings reviewed could include environmental indicators that promote sustainability in universities and thus contribute to climate change, as pointed out by Muñoz et al. [68].

In the results obtained from the research, it can be noted that sustainability, green universities and sustainability of the curriculum are the topics that have generated the most academic controversy since 2007. It is possible to make this inference since the search for information yields few results from before that year.

In addition, it was possible to identify that the accumulated production is increasing which implies that it is a constantly evolving topic that has been consolidating and increasing to the point that since 2013 the publications are increasing and have reached up to 160 publications in the year of 2020 alone (Figure 3).

On the other hand, not only the annual production indicates the evolution of the terms, but other factors also such as the average number of citations of articles per year indicate the value of the academic production and its usefulness in other research (Figure 4). In the findings of the search, it is possible to point out that the articles produced in 2020 are the ones that have been most cited by other researchers. This tendency may be due to the twists and themes published in those years.

Likewise, in the information collected, it was possible to identify Chiou R, followed by Issa T, and then Jaan K as the most relevant authors (Figure 5).

One of the reasons why authors such as Chiou has remained as a significant author in these topics is due to the constant level of publications per year (Figure 6). It is also important to emphasize the relationship that exists between the years, authors and countries that work on these topics, which become the central dynamic of the research process between sustainability, universities and sustainability of the curriculum.

The relationship between the sources and countries of publication provides clues about the dynamics of the researchers. The United States, for example, is the country with the highest number of publications, followed by England (Figure 7). The difference is significant, and shows the importance of these topics. It is also significant to note that no Latin American country appears in the ranking of the top 20 in terms of publications.

Therefore, according to the most frequently discussed topics in terms of sustainability and were considered key words are: curriculum, education, efficient energy, energy education, sustainable development and climate change (Figure 8, Figure 9 and Figure 10).

In this way, publications related to sustainability and curriculum have been growing significantly between 2004 and 2020, with a growth of about 10%, which is largely due to the interest of institutions in implementing processes that are in line with the needs of the world.

Thus, some of the main areas in which most of the publications are grouped correspond to Social Sciences (32.4%), Engineering (16.8%), Environmental (14.2%), among others, showing a direct relationship with these areas of research (Figure 11).

Figure 12 shows the most representative clusters. The red color indicates the number of concepts it contains and the most semantically heterogeneous. In the first subcluster, topics such as greenhouse gases, climate, buildings, environmental, reduction, green chemistry, waste management, green buildings are identified. In the second subcluster, concepts such as educational institutions, environmental protection, green space, students, urbanism, engineering education, planning are presented.

The blue cluster refers to topics very close to the previous one. In this case, it focuses on carbon dioxide studies, environmental impact, life cycle analysis.

Figure 13 shows the collaborations on this topic with the world. The darker shade of blue, the more research focused on this topic. In this sense, it is identified that the countries with the highest production are: United States with a total of 127 publications on this topic, followed by Australia with a total of 64 publications, in third place, China which presents a total of 47 publications, followed by Germany with 44, France with 16 and Spain with 15. In Latin America, the leading country is Brazil with 5 publications.

Some of the main journals that have generated publications on sustainability, curriculum and universities are: International Journal of Sustainability (30%), Cleaner Production Journal (20%), Research in Environmental Education (20%) and Sustainability (15%), which represent 90% of the publications on these topics (Figure 14).

5. Conclusions

Universities are institutions of higher education that, over the years, educate and form the future of the country. Therefore, they have a great challenge in terms of sustainability, the idea to educate for sustainability by projecting a worldview where ecological, economic and social dimensions are included, for the development of skills that generate an ethic of sustainability.

Most university evaluation rankings are based on academic and research performance without considering aspects directly related to the environmental performance of universities or the instruction of students in these subjects.

Although universities have traditionally been evaluated for their academic performance by recognized global university rankings, especially for their scientific production published in mainstream journals, these evaluation systems hardly take into account indicators to measure actions related to the application of sustainability in these institutions, as an emerging principle in their mission functions; even less to know their impact and/or relationship with these mission functions (research, academia, management, extension) of the university.

For future research lines, it is crucial to develop policies that encourage universities to develop sustainability strategies, and in a short time develop new methodologies and indicators that allow for measuring Latin American Universities in terms of sustainability.

Finally, it was found that universities have hardly incorporated sustainability in their academic areas, as can be seen in the evaluation systems of the global academic rankings reviewed, although some measurements were made from an institutional rather than an academic perspective.

There is a need for universities to incorporate elements related to sustainability in their programs, not only in response to the new trends in the countries but also as a factor in responding to the emerging needs of the world in terms of efficient resource management, improving the education and the formation of an integral and responsible professional.

Despite the fact that 16% of Ibero–American universities have been evaluated in the 7 global rankings (without considering SIRiber rankings) and 13% of the universities evaluated are Latin American, when we analyze the bibliometrics we can see that only Spain and Portugal have citations in international journals, with the participation of Latin American countries in indexed publications being insignificant.

Considering all that has been analyzed in this work, the urgency of an international agreement that promotes the implementation of sustainability in universities, both in terms of actions and teacher training, in order to make students aware of these issues and provide adequate training for citizenship, is evident. Special attention should be paid to Latin America, as the rankings that measure university sustainability are difficult to adapt to the idiosyncrasies of Latin American universities. It is therefore necessary to develop indices that are more accessible to educational institutions in countries in the southern hemisphere.

Finally, sustainability is becoming an essential element for universities, especially for the efforts that are generated to strengthen teaching, meet human needs, conserve and improve the natural resource base, use technology, and risk management for the efficient use of resources.