Switzerland has a long tradition of integrating environmental issues within society. One driving concern has been water management. In 1888 a Swiss law protecting fish populations was approved. In 1936, an advisory centre for wastewater treatment und drinking water supply was established at the Swiss Federal Institute of Technology, Zurich (ETH). In the 1940s, the first professional association for ecological water engineering was founded. A further milestone was set by the Water Protection Law of 1955 (Gewässerschutzgesetz). Environmental issues were also integrated within the 1983 Environmental Protection Law (Umweltschutzgesetz), the main body of Swiss environmental law that has since become one of the few core federal domains in Switzerland [12]. The Swiss discourse on environmental protection culminated when sustainability became a constitutional goal in 1999, by which an integration of environmental, economic and social issues in Swiss society and a responsible use of resources are stipulated [13].

A result of this enduring public discussion on ecological issues, as well as the occurrence of accidents such as Chernobyl and particularly Schweizerhalle, both in 1986, was the introduction of the Environmental Sciences curriculum at the ETH Zurich (Eidgenössische Technische Hochschule/Swiss Federal Institute of Technology), the federal university of Switzerland. The lack of and need for experts in analyzing, understanding and handling such problems motivated this step [14,15]. The new educational program started in 1987 and was intended to be practice-oriented and based on a systems view [16]. The curriculum comprised of the following:

The first guide for the educational program of 1989—just before the sustainability concept was spread worldwide—defined the educational goal as “a new type of natural scientist,” both specialist and generalist who knows how to talk to and cooperate with farmers, engineers, public administration and politicians [19]. Since the 1990s, sustainability has explicitly become the educational goal of the ETH Environmental Sciences: “The focus lies on incorporating sustainability, with the goal of applying this concept into future professional activities” [20]. Already in 1997, this educational program was internationally perceived as an example of incorporating “value” (sustainability) into science [21].

Though there is a focus on environmental issues in the ETH Environmental Sciences educational program, sustainability is always taught and practiced from an integrative perspective. Through the mandatory transdisciplinary case studies, the Environmental Sciences students have become an active part of initiatives for sustainable development in half of Switzerland, in rural regions, faced with the problem of defining new, sustainability-oriented roles of farmers [22], as well as in cities, dealing for instance with the economics of the revitalization of industrial sites [23]. The 1995 transdisciplinary case study [24] was part of the development of Zurich West, today one of Switzerland’s most prominent examples for sustainable urban development. Meanwhile, the case studies’ approach of the ETH Environmental Sciences has been cast into a methodology of sustainability learning in higher education [25,15]. Today, several universities in Europe—like the ETH Environmental Sciences educational program—undertake sustainability science partnerships with external public-private and civil sectors agents [26].

From its onset, a comprehensive quality control and evaluation of the success of the curriculum of Environmental Sciences was considered essential. A continual evaluation system was implemented [14] and further supplemented through various other specific evaluation projects running in parallel. In 2009 the evaluative studies were adjusted under a new overarching framework meant to cover both the output of the educational program and its sustainability impact in Switzerland [27].

This encompassing evaluation approach was consistent with the aims of the founders of the program, who considered it to be a crucial step towards a more sustainable development in Switzerland. The distinctive denotation and character of the program, which distinguishes the Environmental Sciences graduates in civil society and the labor market, as well as the attributes of the country—i.e., being rather small, confined and with considerable independence—were factors suggesting that societal sustainability impacts can indeed be evaluated by a combination of quantitative and qualitative methods capturing multiple perspectives.

In 2009 a sustainability impact study was launched in order to assess the specific outreach of the Environmental Sciences educational program of ETH Zurich. The impact was analyzed across the two categories of human and social capital by using a combination of two methodologically different approaches, a quantitative survey and a qualitative interview study (see Figure 1). On the one hand, this allowed to test hypotheses regarding human capital with a large, representative sample, while on the other hand, the open ended nature of qualitative research [28] was seen as a necessity for discovering social capital in the new field of sustainability education [26,29,30].

Expertise can be considered a form of human capital [9,10], as it refers to specific skills and knowledge and results from intensive training and pro-longed education [31]. Expertise is highly domain-specific and difficult to transfer [31]. Therefore, many scholars [32] have suggested analyzing professional expertise only in the context of application. As Mieg [33] has shown, we have to distinguish two factors of expertise related to professional work: expertise as excellence and expertise as professionalism. Expertise as excellence becomes most effective in its own domain, working with already established standards. In contrast, expertise as professionalism is about establishing new standards in a new or foreign professional field.

Thus, to study human capital in the form of expertise, we have to consider the interaction of degree of expertise and particular professional fields. This delivers two types of human capital, here defined as types of experts:

In order to also take into account varying degrees of expertise, the top experts—usually the top 10% performers of a domain—were studied as a third type of human capital. As there is no unique performance measure for advancing sustainability, we focused on organizational positions:

Unfortunately, we lack any quantification for sustainability-related human capital. We therefore established criteria and hypotheses to help assess the sustainability impact of ETH Environmental Sciences on Swiss society with regard to the contribution to human capital, i.e., the impacts triggered by graduates as sustainability experts. The criteria were:

These criteria can be directly transformed into hypotheses related to the three types of human capital or experts previously introduced.

The first hypothesis concerns the graduates as sustainability specialists in the Swiss society. The Specialists Hypothesis contains three parts:

This first hypothesis also reacts to doubts regarding the employability of graduates of Environmental Sciences that accompanied the introduction of this education program from its inception [27]. It was feared that the educational profile would be too narrow and that the leading big industries in Switzerland such as banking or chemical industry would not be interested in such specialists. Therefore, test criteria for part (1) of the hypothesis—concerning the penetration of the Swiss labor market—were: (i) the main three fields of professional activity (particularly employment by universities and small planning offices) should not exceed 50% of all activities; (ii) employment in small organizations (<50 employees) should not exceed 50%; and (iii) no single societal sector should contribute 50% or more to the professional activities of graduates of ETH Environmental Sciences.

The second hypothesis refers to pioneering work by graduates of the ETH Environmental Sciences in the three professional fields that would turn out to be generally weakly related to sustainability (see Table 1). Under the Pioneers Hypothesis, we examine the engagement of graduates as active sustainability pioneers as follows:

The third hypothesis refers to managerial leadership and influence. We do not expect that graduates holding top managerial positions are generally also top sustainability experts. However, we might expect that they bring in their specific human capital and promote sustainability in a substantial way. In this context, we must also clarify whether this contribution is still seen as linked to their academic education in Environmental Sciences. Accordingly, the Leaders Hypothesis contains two parts:

The study used a web-based survey on the careers of the graduates of Environmental Sciences from 1992 to 2005 and their sustainability contributions. Graduates from this time span were invited via e-mail to take part in the survey, which was available online throughout October 2009. The survey mainly elicited self-assessments and covered in particular:

For the items of this survey we generally used a five-point bipolar “Likert” scale. For instance, we asked the graduates whether they experienced an advantage or disadvantage in their professional activities as compared to graduates of more specialized university programs (scale from 1 = clear disadvantage to 3 = balanced to 5 = clear advantage). Two items were included to assess the relation of the professional activities to sustainability. One item asked for the strength of the relatedness of the professional activity to sustainability on a scale from 1 (= no) to 5 (= yes, very strongly), and the second item asked for an estimate of the percentage of work-time devoted to sustainability oriented activities.

In addition, the graduates had to describe and assess best practice examples of their own sustainability-related professional activities such as natural protection projects; sustainability teaching in secondary schools; promoting intercultural gardens in Switzerland; improving the intra-organizational health management of a big company; or the establishment of a spin-off company in the solar energy industry. For instance, the graduates were asked whether efforts for a systematic integration of ecological, economic and social aspects of sustainability were undertaken in their practice example (yes or no), whether sustainability relevant effects had been monitored or evaluated (yes or no), to which of 15 specific objectives of the Swiss sustainability strategy [34] the example contributed (15 items in yes or no format), and how strongly it promoted sustainability (1 = very weak to 5 = very strong contribution).

Altogether 1081 students graduated from the Environmental Sciences program at the ETH between 1992 and 2005. 808 of these graduates could be tracked down and were invited to participate in the study. Of the invited professionals, 567 visited the survey webpage responding at least to the first question (response rate: 70.2%), which asked whether the graduate was currently professionally active, and if so when he or she began their current job. 441 answered the complete questionnaire, representing 40.8% of the total population of graduates, 397 graduates provided one or more best practice example. The graduation years of the survey participants were distributed similarly to the graduation years of all graduates from 1992 to 2005 (Chi-Square, df = 13, p = 0.43).

Table 1 shows the various fields of professional activity of the graduates. 19 fields had a share of at least 1%. More than half of the graduates work in one of the first four fields: private environmental/planning/engineering offices (15.1%); public administration (14.9%); universities (13.4%); or banks and insurances (9.9%). The table also contains the ratings by the professionals of how closely their work is related to sustainability issues and how much work time they devote to sustainability oriented activities. The 19 fields of professional activity differ significantly in relatedness to sustainability and work time devoted to sustainability (ANOVA, F(18,505) = 6.2 and F(18,482) = 7.6, p < 0.001). Both measures are highly correlated (r = 0.84, n = 502, p < 0.001). In all but three fields, work is related at least moderately (>2.5) to sustainability, the exceptions being banks and insurances, the health sector and other public services.

The social capital analysis focused on the transmission of knowledge produced by the ETH Environmental Sciences into the Swiss society and economy. The research question was: Which were the transmission paths from Environmental Sciences into the Swiss social systems? The institutional settings that support the transmission—such as networks—were considered as social capital, as they “facilitate coordination and cooperation for mutual benefit” [6].

The study was based on a social systems approach. Social systems are considered more or less separate fields of social discourse and production, the core social systems being economy, politics, law, and science. The concept of social systems was introduced by the prominent sociologist Parsons [35]. Luhmann [11], who further elaborated the social systems approach, pointed to the difficulties of mutual penetration of social systems, particularly in the context of ecological concerns. The analysis of the economy as a social system was based on the national innovation system concept [36].

The social capital analysis covered the Swiss social systems with the exception of the science system, as ETH Zurich conducted a separate international scientific evaluation of its Environmental Sciences department. For the social capital analysis, we distinguished three social sub-systems: (i) economy (the private sector), (ii) politics/public administration (the public sector), and (iii) civil society. The legal system is usually considered a system of its own. However, we assumed that, in the case of sustainability, law and politics are closely linked [12] and therefore subsumed law under politics/public administration. Furthermore, we differentiated civil society from the public sector because of the high importance of NGOs and other associations whose reach extends far beyond political decision-making. In addition, civil society also includes autonomous professional associations, professions being—besides the national governments—co-actors in the development of university-based scientific disciplines [37]. Thus, civil society is considered a social (sub-)system of its own for the purposes of our study.

Figure 2 provides an overview of the research methodology of the qualitative study. Table 5 shows the research design for the interviews. The study covered three social sub-systems: the private and public sectors and the Swiss civil society. The study comprised four steps, sketched in Figure 2.

A set of five key transmission paths—as functional forms of social capital—was identified. The interactions between ETH Environmental Sciences and the Swiss social sub-systems were sketched on this basis. In the following we present five transmission path theses (in italics) as they have been formulated as a result of the qualitative study (cf. Figure 2):

Our data confirmed the distinction of several functional forms of human capital, i.e., three types of “wealth embodied in labour, skills and knowledge” [3]. We distinguished between specialists, pioneers, and leaders. The pioneers prepare the field in a professional world that is rather “hostile” towards sustainability objectives. The specialists work as experts in a great variety of Swiss industries; they are primarily sought by medium and small-sized firms and support processes of internalization and the dissemination of standards. Leaders are particularly sought by international companies that are players in the globalized economy. In contrast to the specialists, leaders are generalists working, for instance, with global insurance companies to define a corporate sustainability strategy in the face of climate change.

Leadership can also be considered a form of social capital [49]. This was reflected in the quantitative study, with leaders being addressed because of the institutionalized form of influence they represent. However, leadership was not mentioned in the qualitative study as a particular transmission path. The Environmental Sciences education program might be too young to be publicly perceived as a leading societal institution for the advancement of sustainability in Switzerland. A common topic in the interviews, however, was the impact of Environmental Sciences on the standardization of environmental concern in Switzerland, standardization being an example of norms as social capital [7]. Krigsvoll, Fumo and Morbiducci [50] showed the important role of international standardization for sustainability in construction. Our study revealed how, at the Swiss national level, graduates of Environmental Sciences helped to disseminate a shared terminology for discussing and taking decisions on environmental issues. Standardization thus facilitates “coordination and cooperation”—in Putnam’s terms [6]—and contributes to the formalization of modern life [51].

While revealing the important role of standardization, the outreach study also showed limitations. In particular, Environmental Sciences in Switzerland is (still) perceived by the public as an educational program but not as an integrated science. That is why the political or public advice function did not play a major role in our interviews. The public also likely attributes expert advice to, for instance, climate change research or hydrology but not the Environmental Sciences program—despite the fact that the program does indeed educate hydrologists and climate researchers. This fragmented perception might even increase in the coming years, as the ETH Environmental Sciences education program has been transformed from a single diploma course program into a Master’s study program with various majors. The public perception of Environmental Sciences also restrains the further development of the environmental profession in Switzerland. In general, any established profession has to have a clear relation to a—often homonymic—scientific discipline and an academic study program [37,48].

Our study showed how higher education can contribute to sustainability on a national level. We were not so much interested in directly assessing the national sustainability impact—that would have required a sort of sustainability impact assessment [52]. Instead, we studied sustainability outreach in form of supporting intermediary social structures—the functional forms—incorporated by human and social capital [53]. To conceive sustainability contributions as human and social capital aligns with concepts of sustainability that are based on an assessment of resources [54] or the capital stock involved [55]. However, human and social capital might be seen in completely different ways. For instance, the Swiss MONET project (German abbreviation for monitoring of sustainable development) defines the “development and maintenance of human capital” as “collective knowledge and socio-cultural heritage [that] should be maintained and increased over the long term” [56]. Our study defined human and social capital by the line of research put forth by the OECD [1,2], linking it to higher education in particular.

In the international realm of science education, developing human capital at a national level has been an explicit political target for the last twenty years. These efforts to develop human capital are in general linked to investments in social capital, for instance, the development of national systems of accreditation and continuing regular evaluation of education [8]. More generally, research on expert performance teaches us that the optimization of human capital in terms of excellent people—in sports as well as in science—today requires high investments in social capital in terms of professionalized supporting institutions, e.g., for high-level training [33]. Therefore, the success of sustainability-oriented science education might be assessed not only with regard to human capital but also with regard to the development of social capital. In addition to former initiatives towards an accounting of human capital [1], our study might contribute to an accounting of further educational outcomes in the form of social capital, as “[s]olid evidence on outcomes is among the best ways to justify continued public investments in education” [8].

A key to the further development of this human and social capital based outreach assessment will be linking it to an evaluation of single elements of an educational program [15,57]. How do specific courses or theories contribute to the overall sustainability impact of an educational program? In the case of the ETH Environmental Sciences, critical elements could be the transdisciplinary case studies [17] or the systems thinking model [27] on which the educational program is based on. This might require rethinking the role of sciences and science education in the context of environmental and global change [58,59].