Sustainability classifications in engineering: discipline and approach

Abstract

In order to discuss how to advance sustainability in engineering, it is necessary to be clear as to what exactly is the science of sustainability. The linkage between sustainability philosophy and scientific principles has, in some ways, been acknowledged in the wider literature. Moreover, the recent scholarship on sustainability in international literature has focused on providing definitions, policies and methods, though from an engineering perspective, there is an obvious need for clarity on how the engineering and science community can integrate the science of sustainability into practice. Prima facie, this article provides an overview of the development of sustainability science through a textual analysis to collate the underlying discourse and ideology cited in literature. While the number one sustainability challenge is to mitigate climate change, compiling a definition genesis of sustainability will assist the engineering community in gaining an understanding in the underlying philosophical frames. The aim of this paper is to analyse sustainability information in the print press, journals, periodicals and textbooks since publication patterns contribute to our understanding of the cognitive aspects of scholarly knowledge development.

Keywords:

• sustainability science
• sustainability literacy
• social construction
• citation

1. Introduction

So, what is the relationship between sustainability and engineering, if any? Science is aimed at generating true knowledge; engineering is about changing the world (Mulder 2004). In addition, the engineering profession is a practical discipline. Instrumentalist by nature applies science to achieve an outcome, hence it is identified as having a critical position in sustainability since it contributes to improving the well being of mankind, i.e. energy supply, refining minerals, building roads, etc. Thus, engineering is classified as being anthropocentric. The focus of this paper is on sustainability classifications in engineering to enhance the paradigm shift, a paradigm that consists of a multiplicity of attributes. This paper responds to a gap in the literature by explaining what sustainability is for engineering. Currently, in engineering education, there are a large number of papers and special journal issues on wide-ranging sustainability issues; from Universities plans to implementations and an issue which is becoming a leading theme in education, how to convince lecturers to introduce sustainable development into their engineering courses? Boyle (2004) identified problems in incorporating sustainability into traditional engineering education such as a lack of textbooks and a lack of case studies for students to examine. The growing need for this research stems from the following statement that underscored deliberations at the Johannesburg Summit of 2002:

In the ten years since Rio 1992, the international community has spent enormous amounts of money on environmental research; a veritable avalanche of books, papers and reports have been published; and armies of environmental bureaucrats have been appointed. Yet, the world of 2002 is much less sustainable than the world of 1992. Why?

One of the reasons proposed in this article suggests that the engineering and science community remain on the sidelines, with little involvement in the development of sustainability science (SS). In addition, since sustainability is both a transdisciplinary and an interdisciplinary paradigm that consists of a multiplicity of attributes, blame is being allocated in many directions, with accusations such as ‘I thought it was your job, not mine’ being thrown around. The thesis of this paper claims that by understanding the scope of the definitions, the engineering community will therefore be able to develop a unique and universal operational definition of sustainability to be applied in respective disciplines, in order to move beyond compliance issues in terms of environment protection and conservation and repair the extensive damage that our development paradigm has wrought upon the environment and society. The intended aim of this definitional paper is not to add new philosophical propositions or publish another document on sustainability but instead to make sustainability propositions in engineering clear.

1.1 Dissemination of the concept of sustainability

‘Sustainability’ has become widely accepted as a uniting and purposeful focus for the twenty-first century (Batterham 2003). Sustainability theory has gained global recognition today. The debate over how to define sustainability is not new. The definitions of sustainability and sustainable development have become an important global objective. There has been a variety of research investigating sustainability, heralding it as the new industrial revolution in terms of size, scale and transformation but despite two decades of research on sustainable development, a general theory of sustainability grounded on a solid, interdisciplinary framework is still a gap in the sustainability literature (Mudacumura et al. 2006). To approach the subject of SS, there is a need to first explore these questions by analysing differences between applied sustainability, sustainability theory and sustainable development. Applied sustainability, also referred to as operational sustainability, generally refers to the ability to achieve within an existing framework also frequently recognised as performance based in environmental sustainability. Sustainability theory considers the system functioning across its major tenets bridging economic, political, social, cultural, institutional, technological and spiritual ideas. Related research into operational sustainability is also currently being conducted (Atlee and Kirchain 2006, Howarth 2007, Sedlbauer et al. 2007, Davis 2009). On the other hand, sustainable development is the process by which, over time, there has been success in the management of different capital flows in our economy on a genuinely sustainable basis (Parkin et al. 2003). However, applied/operational sustainability, and sustainable development, remains a mammoth task for society.

The notion that history never repeats is contradicted with our traditional reactive institutional responses. It appears that every time society faces a new problem or threat, then a new legislative process is introduced that tries to protect that society from a future reoccurrence (Romano 2004). Hence, to change the status quo thinking and doing is the challenge that lies ahead for the scientific and legislative community because our generation is charged with an unprecedented responsibility that underpins all human activity. To this point, a number of comparative theories exist: the positivist and the pessimist; the scientist and the novice; the believer and the sceptic; the expert and the layman; the righteous and the sinful; the politicians and the noblemen, all suggesting sustainability solutions to solve the planet's problems. Consequently, it would seem apparent that some attention should be paid to the question and definition of SS. Is it a reactive remedy?; A theoretical perspective?; A subject or domain?; A vogue?; A new craze or something to stay? For this reason, it is imperative to conduct this investigation to classify SS to achieve a concise and workable definition of this new domain. The aim of this study is to identify and collate the cited literature on sustainability. The examination process entails finding fairly common patterns or dynamics from multiple cases (Ascher 2007). The investigation was achieved by reviewing the antecedents of contemporary scholarship to examine the theoretical progress towards SS. The results of this investigation will characterise the new developments to arrive at the current state of knowledge sustainability.

1.2 Overview of prior research

Recent years have seen a growth in SS research in response to the upsurge of the sustainability debate (Kates et al. 2001, Jaeger 2002, Clark and Dickson 2003, Kates and Thomas 2003, McMichael et al. 2003, Mihelcic et al. 2003, Reitan 2005, Komiyama and Takeuchi 2006, Martens 2006, Potschin and Haines-Young 2006, Clark 2007, Kajikawa 2008). Jointly, the nucleus of SS is asking: How are long-term trends in environment and development, including consumption and population, reshaping nature–society interactions in ways relevant to sustainability? While this article acknowledges the previous research debates, the current state of knowledge requires a classification, an abridgment of SS. Since a clear and concise description of what is unfolding remains broad, the broadening focus motivated this research to collect all the evidence and construct a datum underlying SS developments. Buoyed by these findings, this paper sets out to present a review of SSs by exploring an important driver: the plethora of sustainability definitions and considerations. Upon completion of this review, the key findings will provide a common framework supporting the emerging discipline of SS (Turner et al. 2003). The results of this investigation are divided into three associated sections. First, it presents a compilation of published definitions; the second section provides new linguistic terms in the print media and discusses the materialisation of the discipline and approach; and finally, the third presents a summary of sustainability-related journals and periodicals. While it acknowledges the cumbersome task of reviewing all existing publication trends in books, journals, assessments tools or method of SS and discourse in the print media, it is noteworthy to mention their existence.

2. Research methods and results

The present review focuses on descriptive analysis; consisting of searching, assessing and integrating sustainability scholarly articles, books and other sources such as dissertations and conference proceedings, thereby presenting an account of what has been published on sustainability by accredited scholars and researchers. It begins by reviewing the literature on definitions.

2.1 The anthology of sustainability definitions

The original World Commission on Environment and Development (WCED) publication (Bruntland 1987) invoked public interest in sustainability, posing challenges such as the management of contractive problems, acceptance that the world is faced with an environmental crisis, and the idea that society must make a fundamental change to overcome the crisis, for example, growth vs. limits, intergenerational vs. intragenerational equity and individual vs. collective interests (Dovers and Handmer 1995). The origin of the term ‘sustainable development’ in contemporary terms is usually credited to the Brundtland Report (Holden 2008); however, the Bruntland Report was not an isolated project; it had built on the previous work of the Club of Rome (Meadows et al. 1972). Furthermore, it had come together as a joint effort between many institutions and governments. Essentially, from the time when sustainability was first popularised by the Brundtland Report in 1987 to the present day, numerous efforts have been made by different groups, organisations and individuals to capture a common interpretation of the concept. Meppem and Gill (1998) wrote that few concepts have been applied with less precision and consistency in policy circles than ‘sustainability’. The concept is now espoused at all levels of government and industry throughout the world, though rarely in a uniform way. This has been noted by some, including (Gell-Mann 1994), who suggests that, while ‘today many people are busy writing the word “sustainable” in pencil, the definition is not always clear’. Additionally, Costanza (1994) asserts that ‘to a large degree the sustainability concept is not internalised and the ramifications of internalisation are poor’. Furthermore, some of the confusion around SS exists due to the lack of clear-cut information. The following are examples of some of the criticisms cited in literature (Costanza 1994, Leal Filho 2000, Martens 2006):

1. sustainability is not a subject per se since it is not classified as being part of the domain of any given science;

2. sustainability is too theoretical;

3. sustainability is too broad for engineering;

4. sustainability is too recent a field and

5. sustainability is a fashion accessory.

The review focuses on answering the following research questions and analysing each of the definitions of sustainability:

1. Is a new SS emerging?

2. Does the literature support the claim?

3. What is SS?

4. How is it characterised? Is it a trans-, inter-, or multi -disciplinary scientific approach?

The word ‘sustain’ has been in the language for thousands of years. It comes from the Latin sustenare meaning ‘to hold up’ (i.e. to support). From there, it evolved long ago to mean ‘to keep something going or extend its duration’, with an overtone of providing the support or necessities that made the extended duration possible, e.g. a sustaining meal; ‘sustain’ to cause to continue (as in existence or a certain state, or in force or intensity); to keep up (especially without interruption, diminution, flagging, etc.); or to prolong. A number of notable authors have attempted to define sustainability, as listed in Appendix B and are classified in terms of the year of publication, the main or first author and a brief description of the findings followed by an objective classification of the definition. The Bruntland Report is considered the modern genesis of the sustainability movement, and of the papers listed in Appendix B, the WCED (Bruntland 1987) is the most often cited definition: ‘development that meets the needs of the present without compromising the ability of future generations to meet their own needs’.

Perhaps, it is worth noting a key question: Why is sustainability, as a process, in some contexts so difficult to understand (Leal Filho 2000)? There are various reasons, but considering the earlier mentioned collection of definitions, it is easy to see the reason for the attitude variation towards definitional sustainability. More importantly, the broadness was answered by Seager et al. (2004) who defined sustainability as a shared ethical belief. It is important to note that more often than not, the concept of ‘sustainability’ is presented as an ideal state. It is also useful at this point to review some of the more considered articulations of the sustainability concept. Definitions can be classified either in positivist or in normative terms. Keynes (cited in Meppem and Gill 1998) declared that a ‘positivist science may be defined as a body of systematised knowledge concerning what is; a normative or regulative science as a body of systemised knowledge relating to criteria of what ought to be’. Various definitions have been suggested, which are all very similar, yet are open to interpretation and still remain somewhat ambiguous. Leal Filho (2000) reports that the expression ‘sustainability’ has been traditionally used as synonymous with words such as ‘long-term’, ‘durable’, ‘sound’ or ‘systematic’ among others. Dobson (1998) connected sustainability to justice: ‘subordinate to justice’. Indeed, out of the context of the English language, sustainable development is very often referred to as ‘Développement durable’ in French, while word-for-word translations are found in German (nachhaltige Entwicklung), Spanish (desarollo sostenible) and Portuguese (desenvolvimento sustentaÂvel).

Sustainability is defined differently within and between cultures, and its definition has changed over time. The concept of sustainability is a complex one; however, it is possible to distil some of its most basic and general characteristics by adopting a systemic approach. Acknowledging the lack of an agreed definition of sustainability, Mebratu (1998) proposed that there were three main ‘versions’ of sustainability: institutional, ideological and academic, as shown in Table 1. However, in considering our search for a definition of SS, the critical theory and the analysis of institutions, ideologies and academic perspectives presented in Table 1 underpin the application of sustainability in its own context. However, the normative interpretation most widely quoted in sustainability is that expressed by the WCED (1987).

Table 1 Institution, ideology and academic versions of sustainability (Mebratu 1998).

Institution	Drivers	Solution epicentre	Solution platform	Instruments (leadership)
World Commission on Environment and Development (WCED)	Political consensus	Sustainable growth	Nation-state	Governments and international organisations
International Institute for Environment and Development (IIED)	Rural development	Primary environmental care	Communities	National and international NGOs
World Business Council for Sustainable Development (WBCSD)	Business interest	Eco-efficiency	Business and industry	Corporate leadership
Ideology	Liberation theory	Source of environmental crisis	Solution epicentre	Leadership centre
Eco-theology	Liberation theology	Disrespect to divine providence	Spiritual revival	Churches and congregations
Eco-femininism	Radical feminism	Male-centred epistemology	Gynocentric value hierarchy	Women's movement
Eco-socialism	Marxism	Capitalism	Social egalitarianism	Labour movement
Academic discipline	Drivers (epistemological orientation)	Source of environmental crisis	Solution epicentre	Instruments (mechanism of solutions)
Environmental economics	Economic reductionism	Undervaluing of ecological goods	Internalisation of externalities	Market instrument
Deep ecology	Ecological reductionism	Human domination over nature	Reverence and respect for nature	Biocentric egalitarianism
Social ecology	Reductionist- holistic	Domination of people and nature	Co-evolution of nature andhumanity	Rethinking of the social hierarchy

For the purposes of developing a definition of sustainability, it is suggested to consider analysing sustainability literature using a ‘systems model’ approach. The advantages of such an approach are several; especially as it provides a wholesome view of the defining activity. Initially, in defining this ‘system model’, it was considered a system simply defined as a set of interrelated elements or subsystems. The elements can be molecules, organisms, machines or their parts, social entities or even abstract concepts. Hence, compiling sustainability definitional literature is considered via the interrelations, interlinkages or ‘couplings’ between these elements, which may also have very different manifestations within the system, i.e. economic transactions, flows of matter or energy, causal linkages, etc. (Gallopín 2001). Similarly, the process of adapting or acclimatising sustainability definitions is part and parcel of a system model where contextual modifications are made at sublevels to achieve an individualised outcome.

According to Kajikawa et al. (2007), the accumulated number of publications is increasing exponentially. Furthermore, the SS approach has evolved over the past quarter century to its current state, given that science starts with an object of study, then analyses it in order to understand it and the analytic results accumulated by scientists contribute to the development of new scientific disciplines. As the analytical process advances, its object of study grows narrower. As analysis becomes more specific and detailed in its focus, scientific disciplines themselves become increasingly narrow and specialised (Yoshikawa 2008). The following transcripts are snippets of how the domain has evolved in the literature. A number of notable researchers have provided meticulous studies of the domain (Kates et al. 2001, Clark and Dickson 2003, Reitan 2005, Komiyama and Takeuchi 2006) and concluded that it was not an exclusive domain, rather a transdisciplinary approach. According to Clark (2007), SS is not yet an autonomous field. Keiner (2004) provided a lot of definitions and models for its explanation, ranging from triangles and prisms to eggs. Kates et al. (2000) and Kates and Thomas (2003) wrote that sustainable development exhibits broad political appeal, but has proven difficult to define in precise terms. While much literature made a case and promoted the dawn of the new discipline/metadiscipline, Mihelci et al. (2003) described it as a new field of science that seeks to understand the fundamental character of interactions between nature and society and to encourage those interactions along more sustainable trajectories. Matson et al. (2007) described an emerging field of research which integrates the physical, biological and social sciences as well as medicine and engineering. Pachauri (2008) showed its multidisciplinary themes that examine the scientific aspects, the engineering aspects and also the social science aspects of a problem. Fricker (1998) described sustainability as a concept that has captured our imaginations and aspirations and as a tangible and identifiable goal that eludes us.

According to Kajikawa (2008), it was noticed that some sustainability dimensions are related to institutional definitions in view of the fact that human beings traditionally have used an ‘adaptation strategy’ under environmental uncertainty and vulnerability. Adaptation strategies are classified into three types: institutional, behavioural and technological. Institutions and their associated policies are one of the three key dimensions of adaptation to climate change. This institutional strategy is in agreement with the definitions of sustainability listed (Mebratu 1998). Although environmental protection, macroeconomic stability, good governance and respect for human rights, appropriate technology and technical soundness are all necessary if development interventions are to continue to yield benefits, they will amount to little without sustainable institutions (Brown 1998). Institutional sustainability is therefore no less and in fact, one could argue, is far more important than the other notions of sustainability mentioned above, as all these are ultimately dependent on institutions.

Thus far, literature indicates that aspects dealing with the value of the environment are conceptualised as nature. The second is the temporal dimension of intergenerational equity, and the third is the spatial or social aspect of intragenerational equity. These aspects relate to the scientific operationalisation of sustainability from ecological, economic and social points of view, respectively (Becker 1997). O'Riordan (1988) offers various interpretations of social change that influence the characterisation of sustainability. According to O'Riordan, there is a distinction between sustainability and globalisation. He emphasises how discourse patterns vary from the disciplinary perspective, i.e. political, ecological, economic, anthropological, legal and sociological, as shown in Table 2, to comparative tables for translating this material into discourses of globalisation and localisation. Although it would be a cumbersome task to cover exhaustively all the definitions that are mushrooming from literature, a growing body of evidence suggests lengthy debates on the definitions of sustainability. It is offered as normative, and most of them articulate sharable concepts (Orecchini 2007). The horizon of definitional meanings refers to a junction of at least five domains: economic, environmental, technological, institutional and social, which comprise equity and justice, as well as cultural and spiritual meaning in equal measure. These considerations of terminology indicate that there is a strong normative component in the concept of sustainable development (Becker 1997). Another angle to view the broad definitional meanings of sustainability is by evaluating the relationships between human beings and the planet, human social union and our moral fabric. The attempt to study the value of sustainability by relating social benefits of products and services to satisfying human needs is conceivably best answered by Maslow's hierarchy of human needs (Maslow 1954), which articulated the five levels of human needs. The common ground between Maslow's concept and sustainability is described in the lower order needs in the pyramid, since it stipulates that higher needs in the hierarchy only come into focus once all lower needs are entirely satisfied (i.e. basic needs: sufficient food, clean water, hygienic living conditions, etc.). Ecological sustainability rests upon securing the basis of life and industrial production without compromising the global long-term functioning of the environment (Von Hauff and Wilderer 2008). Therefore, sustainability, may be something more grand and noble, a dynamic, a state of collective grace, a facet of Gaia, even our spiritual understanding (Fricker 1998).

Table 2 Summary of sustainability science findings.

Taxonomy	Component	Number	Units
Knowledge	Sustainability definitions	61	Definitions
	Sustainability periodicals and journals	117	During 2008
Comprehension	Sustainability-related papers	3000	Annually
Application	Institutional policy (Kyoto)	Unlimited	Unlimited
Analysis	Linguistic reference	35,000	Citations
	World Wide Web presence (search engine)	60	Million
Synthesis	Sustainability degree programmes in OECD	15	Programs
Evaluation	Sustainability metrics assessments (indicators)	60	2008
	Sustainability software tools	21	2008

Finally, sustainability is a management methodology of how to prioritise our consumption of resources and hence minimise our footprint. This opinion was supported by Anastas and Zimmerman (2003) in ‘The 12 Principles of Green Engineering’. Skinner (2004) highlighted the need for definitions of sustainability and interpretation to be ones that are everyday workable that embody concepts of long-term endurance and continuance in spite of variability and even adversity in the contextual setting. Bagheri and Hjorth (2007) propose that the major challenge in dealing with sustainability is to develop a means for practicing the paradigm in the everyday planning and management of a society. It calls for proponents of human, economic, as well as environmental concerns to join together to provide an everlasting life for the human species in the global ecosystem. To this end, the notions of progress and sustainability are twinned concepts inextricably bound together.

2.2 Sustainability discourse

The main reason periodicals and journals were investigated was to establish sustainability literacy in literature because the number of citations is usually considered as one important indicator of the scientific impact in a particular field. Sustainability Literacy is a term which is usually used metaphorically to refer to the knowledge and skills necessary to contribute to a more sustainable society (Stibbe 2007). It is also worth noting that most major English dictionaries, including the American Heritage Dictionary, Oxford English Dictionary and Merriam-Webster's Collegiate Dictionary have had an entry for sustainability since the mid-1990s. Garfield (1973) claimed that because citation frequency is a measure of research activity or of communication about research activity, it reveals the impact of a particular publication or scientist. In addition, according to Berkenkotter and Huckin (1995), new scientific knowledge is disseminated within the scientific community primarily through peer-reviewed journal articles, but the rest of society becomes informed largely through the mass media.

According to Zimmerman et al. (2001), the popular print media constitutes a major source of new information about scientific research for the public and for members of the scientific community outside their areas of expertise. Hence, the enthusiastic usage of the term ‘sustainability’ in the English language print media according to Tomich et al. (2007) is significantly increasing. This is illustrated in Figure 1. Further examples, as seen on the World Wide Web, reflect a full spectrum of general information, ranging from minimal or null to highly authoritative. It is considered an information sea which is still best described as ‘quantity without quality’. This has made the Internet a large information ocean (Yunjing et al. 2002). Hence, in order to establish web usage of the term ‘sustainability’, a web search on ‘sustainable’ or ‘sustainability’ was conducted. The search retrieved pertinent information; however, it did not include any qualitative evaluation or filtering of the content, although the relevance rankings offered by some browsers revealed the frequency of the terms stated in the query. For example, a recent google.com and yahoo.com search for ‘sustainable’ and ‘sustainability’ retrieved more than 60 and 75 million records, respectively. Figure 2 presents the number of papers containing ‘sustainable’ or ‘sustainability’ in the title or abstract where the black circles and white circles are the number of annual publications and the accumulated number of publications, respectively, which present the birth of SS in a contextual perspective. Kajikawa et al. (2007) estimated that over 3000 papers are published in the field annually.

Figure 1 Use of the word ‘sustainability’ in mainstream media (Tomich et al. 2007).

Figure 2 Number of academic published papers (Kajikawa et al. 2007).

Exploring the linguistic theme, Bastardas-Boada (2005) describes language as not only defined by its grammar or its lexis but also by living human cognition, interaction and identification, in the simultaneous intersection of the noosphere, the psychosphere and the sociosphere. To validate the rising coverage of sustainability in both language and print media, Nash and Bacon (2006) reported on non-randomly chosen samples of six English-language newspapers in Southeast Asia, with a side comparison to a leading Australian newspaper, regarding their coverage of environmental sustainability and ecological issues confronting societies locally or globally, over a limited period of time. It was reported that the subjects generated more than 5% of the total coverage for any one paper. From this perspective, Linguistic Sustainability emerges with the increase of citations in both the print media and the web. Considering the role that language and socio-linguistic aspects play in forming social structures, the consequent impact of those structures on the literacy of society is well supported by social construction and language and social change theories, as in Cooper (1989), Nightingale and Cromby (1999), Gergen (2000), Stibbe (2001), Berger and Luckmann (2002), Burr (2003) and Fairclough (2003). Therefore, SS is making advances in popular language and thus supports the existence of this new domain.

2.3 Sustainability journals and periodicals

In order to ascertain the growth and development of ‘sustainability’ literature in research, this study examined the contribution made in academic journals, periodicals and newsletters using an electronic database to gather citations matching specified keywords covering environmental communication topics in literature from relevant indices. These terms were ‘sustainable’ and ‘sustainability’. The indices used were the Institute for Scientific Information, Ulrichsweb Abstracts Citation Index (Web of Science) and Periodical Abstracts (Pro-Quest Direct). To congregate citations, search word combinations were used in all the investigations in titles to determine research output of publicly available literature. It was found that the terms ‘sustainable’ or ‘sustainability’ were featured in the titles of 117 journals and periodicals. The data provides new insights into the developments of this emerging science field. The data is plotted in a histogram shown in Figure 3, each block represents the total entries within that time frame, for example, the period between 2000 and 2005 witnessed a peak of new entries, followed by an almost 50% less new entries in the next period, indicative of an emerging area. Furthermore, in a recent review of the research literature on sustainability simulation models, it was found that in terms of computational technologies, 21 new software developments were found. These are illustrated by country of origin, as shown in Figure 4. Appendix A lists the search results of periodicals launched to meet both academic and social demands of sustainability since the early 1990s.

Figure 3 Sustainability journals and periodicals in existence.

Figure 4 Sustainability software listed by country.

3. Discussion

Many educational engineering institutions are moving to incorporate sustainability engineering into their curriculum but each institution has its own interpretation of sustainability engineering and its applicability within an education programme (Boyle 2004). As such, it is important to consider the dynamics of the discussions of sustainability definitions and how it may facilitate engineering involvement. This section begins by reviewing the ontology for SS. Ontology is a collection of concepts and relationships; among these concepts in a specific domain (Badal et al. 2004). Sustainability ontology has moved from a concept used more as a policy guide to a true science state approach with a sound scientific basis. Furthermore, sustainability ontology can also be seen as large taxonomies. SS exists in relationships, and its stature is confirmed by the theoretical and practical perspectives offered in the definitions, periodicals and journals, academic qualifications, linguistic developments and metrics. The perceived value of sustainability as a discipline in the scientific community is confirmed by the upsurge of new textbooks and SS journal titles. The linguistic fluency of the results of these findings is summarised in Table 3.

Table 3 Discourse patterns that apply to sustainability transition, globalisation and localisation, adapted and modified from O'Riordan et al. (2001) and O'Riordan and Voisey (1997).

	Market	Regulatory	Equity	Revelatory
Myths of nature	Expandable	Precautionary	Breached	Negotiated
Social values	Limits	Limits	Limits	Limits
Policy orientations	Price signals	Rules of contracts	Equality of opportunity	Communication
Distributional arrangements	Markets	By agents of rule-makers	By democracy	By negotiation
Generating consent	Compensation	By agreed rules	Negotiation and compensation	By reasoned discussion
Intergenerationality	Future looks after itself	Future helped by present	Future planned by present	Future envisioned
Liability	Spread losses	By redistribution	Burden sharing	By negotiation mechanisms
Globalisation	Expandable limits	By agents of role makers	Mixed scanning for vulnerable	Evaluation of social responsibility
	Competitive advantage	By common agreement	Reliance or global watchdog activities	Corporate and governmental
Localisation	Initiative	Precaution and pragmatism	Social-local identity	Deliberative and inclusionary procedures
	Opportunism through social markets	Links to global standards negotiated by local stakeholders	Local citizenship initiatives through social networks	Social commitments to participatory involvement through best value procedures

The literature is divided into three phases: the mid-1970s hub which was a response to the limits of growth; the mid-1980s which observed the emergence of sustainable development literature; and the mid-1990s which focused on clarifying the distinction between sustainability and sustainable development (Hasna 2004). In this first decade of the twenty-first century, society is witnessing a fusion of the previous three decades of research materialising as a new domain. The New Scientist Special Report: The folly of growth? (2008) reviewed 12 recent books on economic growth and overconsumption, and the consequences for environmental sustainability (Goerner et al. 2008). The New Science of Sustainability proposes that as a science or discipline, sustainability is, as one expression of interactions between natural and social systems, a healing response. According to Holmberg et al. (1996), by 1994, there were more than 80 different definitions and interpretations fundamentally sharing the core concept of the WCED's definition. According to Parkin et al. (2003), 200 definitions of ‘sustainable development’ exist. By the mid-1990s, there were well over 100 definitions of sustainability (Marshall and Toffel 2005). Hasna (2007) confirmed 61 sustainability definitions as per Appendix B to hand there seems to be as many published definitions of sustainability as well as journals and periodicals that carry either the name sustainable or sustainability in their titles refer to Appendix A. That is not to suggest these are the only published avenues of material dealing with this subject matter. However, if defining sustainability is difficult, putting it into practice is yet to be seen (Parkin et al. 2003). As for definitional consensus, it is held that sustainability is not a problem, nor an end point; rather, it is a process and a vision involving renewed awareness of the natural environment and interaction with it. According to Becker (1997), terminology used in the definitions indicates that there is a strong normative component in the concept of sustainable development. It is to be expected that SS would foster sustainable development and will deal specifically with all four elements of sustainability as outlined earlier. It therefore becomes possible to state the following: in terms of the definitional fragmentation, it is appropriate to recognise that the character and behaviour towards sustainability are mainly defined by the individual's education: knowledge, background, experience, perception, values and context (Leal Filho 2000, Hatch and Schultz 2004, Austgard 2007, Murray and Murray 2007). Therefore, definitional universality can be achieved by classifying the existing variety of definitions of sustainability into four major groups, depending on the constituent representation reflected. These are (a) institutional systems-based, (b) ideological stewardship version, (b) academic version and (c) physical version, economic, social, natural and technological. However, in terms of the definitions of the new paradigm, Clark and Dickson (2003) reported that SS focuses on the dynamic interactions between nature and society. These two dimensions, along with economics, form the foundation of sustainability criteria for assessment. Martens (2006) wrote SS is academic and social, trans- and interdisciplinary, participative, uncertain and exploratory, with its central elements co-evolution of a complex system and its environment, co-production of knowledge, co-learning, learning by doing and doing through learning. The relationship of discipline integration and SS was plotted by Martens (2006), covering functional and multifunctional theory as mapped in Figure 5. In addition to the above definitions, a consensual SS definition is one that recognises the synergies and constraints among nature, economic activities and people; it is a tool or methodology that endorses sustainable practices for meeting fundamental human needs while preserving Earth's life support. An applied example in support of this newly growing science domain is that SS has made way into many reputable education institutions, schools, universities and governmental agencies as a field of study. For example, Central Queensland University's Department of Sustainability incorporates the engineering schools, and the Victorian Government's Department of Sustainability and Environment, and similarly in the United States of America, Stanford University's Department of Sustainability and Energy Management. In addition, at the beginning of the academic year of 2007, Harvard University commenced a SS degree programme. Harvard reported that it was seeking to advance the basic understanding of the dynamics of human–environment systems, to use that understanding to facilitate the design, implementation and evaluation of practical interventions that promote sustainability in particular places and contexts, and to improve linkages between relevant research and innovation communities on the one hand, and relevant policy and management communities on the other hand.

Figure 5 Sustainability science trans- and interdisciplinary (Martens 2006).

Another applied example is witnessed in one of the key heavy industrial areas in Australia, specifically, Gladstone, Queensland and Kwinana, Western Australia where sponsorship of synergies and interactions along more sustainable trajectories is demonstrated. These industrial areas are home to alumina, nickel and oil refineries, pigment and chemical plants, aluminium smelters, cement industries, coal export terminals, power supply and the first commercial direct reduction iron making plant. These industries have a traditional collaboration in areas of mutual interest, such as raw materials and community relations, in addition to safety and environment. It is also encouraging to see resource synergies that provide a significant avenue towards sustainable resource processing via exchanges of by-products such as water and energy between companies: one chemical plant's waste is another plant's feedstock. There are also international examples of industrial symbiosis such as Styria in Austria, Rijnmond in The Netherlands, Humber in the United Kingdom, Tampico in Mexico, Map Ta Phu industrial estate in Thailand and Alberta in Canada.

From the definitions and other cited knowledge, it appears that SS is an interactive attempt among disciplines. In other words, it is interdisciplinary and transdisciplinary and hence cannot be set into one area. It is noted that a fusion of interdisciplinary disciplines is channelled to create SS as known today. This field is developing at a fast pace where the number of annual publications is increasing linearly. This was briefly demonstrated in Figure 2.

Using the evidence of definitional descriptions of sustainability, this section has established the engineering context of sustainability. Primarily, the divergence of definitions evolved from the confluence of many themes including ecosphere, local and global vision, the consequences of humanity's influence on a planetary scale, human social welfare, human values, knowledge of ethics over different periods of time, management of resources (limitation) from cradle to cradle, and social and cultural context through promotion of social justice and environmental awareness. As a result, in classifying the budding mechanism of SS using Bloom's (1956) six levels within the cognitive domain of intellectual behaviour to verify the development of sustainability: knowledge, critical comprehension and practical application (analysis, synthesis and evaluation). The notion of Bloom's characterisation offers many benefits to elaborate this theory. It creates a common ground for discussions about SS goals and objectives and it helps in the steering and alignment of SS. The structure of the SS concept is illustrated in Figure 6 where the operational/applied sustainability propositional framework leverages the founding sustainability dimensions, leading it to policy shift or new paradigm.

Figure 6 Characteristics of sustainability normative.

Mind-independent thought compels us to ‘accept the world as it is’. It is governed by physical laws that are a reality which recognises the systemic nature of the universe and gives consideration to the notions of truth. Knowing that engineering has provided the infrastructure of human progress, are engineers ethically compelled to resist contributing to products or services that aid and abet ‘overconsumption’? This includes dissipative use of raw materials and production of waste at rates higher than sources or sinks regenerate. High technology engineering projects (e.g. superhighways, dams and skyscrapers) and engineered processes (e.g. wastewater treatment) can be viewed as works exemplifying the goals and progress of current industrialised society. However, many of our current engineering practices also contribute to urban sprawl, loss of biodiversity via habitat destruction, unsustainable use and conversion of resources and degradation of essential services that functional, healthy ecosystems provide (Rosemond and Anderson 2003). For this reason, new academic programmes are appearing in academic institutions. These include industrial ecology and, recently, ecological engineering resembles chemical, hydrological and other engineering programmes in which the prefix denotes the discipline specialisation. On a different note, civil, mechanical or electrical engineering titles indicate engineering subdivisions based on areas of application. The ecological engineering title is twice asymmetric: it indicates a kind of engineering, not science (engineering ecology); and only part of ecological science has as yet been included in ecological engineering. The ‘civil’ engineering descriptor is defined by its context, rather than this area being defined by its descriptor. Civil engineering includes a specialisation with an inappropriate title, environmental engineering (Painter 2003). Hence, the profession in general needs to consider minimising anthropogenic perturbations to natural cycles, especially cycles of the key elements (carbon, nitrogen, phosphorus and sulphur) of biological life and not just individual disciplines or sub disciplines. Although the basics of this concept can be understood by most, understanding sustainability engineering requires a greater maturity than that of most engineering disciplines (Boyle 2004). According to Madea and Hibiki (2008), SS is not only made up by a single academic field fractionalised as in the past, but also by problem solving-based approaches. Therefore, SS is not an autonomous science per se, it is neither pure nor applied, but it is a practical scientific subject. It has a functional scientific articulation which relates to planetary and benevolent application of the existing scientific domains. It is one that integrates and defragments multiplicities of logical attributes from scientific knowledge across many disciplines. It solves various problems concerning human existence; it reflects a humane message underpinned by scientific, social, technological and economic disciplines, public and private sectors, local and global, academia and government perspectives.

The evolution of this discipline is through various components as shown in Figure 7, placing the central theme or unifying factor in the centre of Figure 7 where sustainability definitions are outwardly radiating sub-themes surrounding the definitions, thus yielding an integration of the different components that make up the science to produce the new field of study. By doing so, this article has also answered the questions raised by Leal Filho (2000) by demonstrating that sustainability is a subject per se and it should be classified as comprising 15 main research domains as purported by Kajikawa et al. (2007): agriculture, fisheries, ecological economics, forestry (agroforestry), forestry (tropical rain forest), business, tourism, water, forestry (biodiversity), urban planning, rural sociology, energy, health, soil and wildlife.

Figure 7 Components of sustainability science.

4. Conclusion

This paper has examined literature to validate the specific contributions that engineering can make to the development of a universal operational definition of sustainability. Whether sustainability and, in turn, sustainable development is determined to be a discipline or transdiscipline is not going to change the world or the status of the sustainability progress per se; however, it is important to seek clarity regarding engineering education, hence determining the strategy to embed in the engineering curriculum. It follows that if pollution is not created in the first place, then there is no need for clean-up and remediation technologies. Engineers are yet to adopt accountability and avoid finger pointing. For this reason, the author acknowledges some of the weaknesses of reductionist theory, however, the facts remain that ‘if pollution wasn't created in the first place, there would be no need for clean-up and remediation technologies’. Sustainability is an ‘engineering responsibility’. Since the interest of this paper is to investigate the growth of sustainability scientific knowledge and is motivated by the tenets of science to ‘create conclusion from evidence’, this article has provided an overview of some key contexts of SS discourse theory to address how a sustainability philosophy or culture in engineering might drive development towards net positive outcomes, rather than the current focus on minimising negative impacts on the environment and society. The ontology on SS is derived from journals, books and linguistic behaviour. Generally, SS is proving to be different from previous numerical sciences because it crosses transdisciplinary borders. This is confirmed by the representation of SS in social, economic, natural, technical and institutional areas. Furthermore, the birth of this emerging transdiscipline is identified by the drivers and factors that can be expected to signify the formation. SS is more than just relations between the economy, society, technology and the environment. Important though these interconnections are, they are largely only the external manifestations of SS. This article has considered and discussed the context of literature citations interpretations of SS and the convergence of definitions. It is of no surprise that the sustainability definition presented in this paper is a holistic process, where all living matter subsistence is respected, emanating not as an end point, but rather a journey. Furthermore, it is a vision involving renewed awareness of the natural environment and interaction with it. This article has revealed this new paradigm. Hence, sustainability is a new science, an emerging discipline, an evolving approach. Indeed, the analysis suggested that it is sturdily promising with multiple interpretations and multiple dimensions, and a complexity of issues. While the article provided some broad results indicative of the growth of the discipline, it also revealed that it is a flourishing field that is still developing in literature. This paper has attempted to simplify a complex and diverse topic to defragment and support the new paradigm with scientific evidence of its development.

Journal title	Year	Journal title	Year
Agronomy for Sustainable Development	2005	Journal of Sustainable Development in Africa	1999
Agronomy for Sustainable Development	1981	Journal of Sustainable Forestry	1993
Alberta. Ministry of Sustainable Resource Development	1996	Journal of Sustainable Tourism	1993
Biological Conservation, Restoration and Sustainability	1999	Living Sustainably	2005
British Columbia. Legislative Assembly. Special Committee on Sustainable Aquaculture	2005	Local Environment: The International Journal of Justice and Sustainability	1996
Canadian Environmental Sustainability Indicators. Air Quality Indicator	2005	Made in Holland. Sustainable Health Care	2004
Canadian Environmental Sustainability Indicators. Freshwater Quality Indicator	2005	OECD and Environment and Sustainable Development	1997
Canadian Environmental Sustainability Indicators. Greenhouse Gas Emissions	2005	Our Sustainable Future
Canadian Heritage. Sustainable Development Strategy	2003	Passive Solar Journal: Heating, Cooling, Hybrid Technologies and Strategies for Sustainable Design	1982
ChemSusChem: Sustainable Chemistry Journal	2008	Proceedings of the National Academy: Sustainability Science	2007
Commissioner for Environmental Sustainability	2004	Profitable Farms, Sustainable Systems, Healthy Landscapes Project Update	2006
Commissioner of the Environment and Sustainable Development to the House of Commons	1997	Public Health Agency of Canada. Sustainable Development Strategy	2007
Copper Volume II: Health, Environment and Sustainable Development	1995	Public Works and Government Services Canada. Sustainable Development Strategy	1997
CSA Sustainability Science Abstracts	2005	Renewable and Sustainable Energy Reviews	1997
Energy and Sustainable Development Magazine	2004	Renewable Energy World	1996
Energy for Sustainable Development	1994	SA Water. Sustainability Report	2003
Energy Resource and Environmental Sustainable Management	1996	Science and Technology for Sustainable Development. 5NR Biennial Report	1996
Energy Sustainable Development: The Journal of the International Energy Initiative	1994	Source OECD Environment and Sustainable Development	1997
Engineering Sustainability, Proceedings of the Institution of Civil Engineers	2003	Sustainability Journal: Swedish Research for Sustainability	1994
Environment Canada's Sustainable Development Strategy	2000	Sustainability Report	1995
Environment, Development and Sustainability: a multidisciplinary approach to the theory and practice of sustainable development	1999	Sustainability Science, Springer	2006
Environment: Science and Policy for Sustainable Development		Sustainability, Economics, and Natural Resources	2005
Environmentally Sustainable Development Proceedings Series	1994	Sustainability: Science, Practice, and Policy	2005
Ethiopian Journal of Technology, Education and Sustainable Development	2005	Sustainability: The Journal of Record	2008
European Directory of Sustainable and Energy Efficient Building – Components Services Materials	1993	Sustainable Building	2006
Forum for the Future. Sustainable Economy Programme. Policy Briefing		Sustainable Business Investor – America	2000
Health Canada. Sustainable Development Strategy	2000	Sustainable Development	1993
International Institute for Environment and Development. Sustainable Agriculture Programme. Gatekeeper Series	1987	Sustainable Development Digest	2007
International Institute for Environment and Development. Sustainable Agriculture Programme. Hidden Harvest Research	1993	Sustainable Development Law and Policy	2001
International Journal of Agricultural Sustainability	2003	Sustainable Development Strategy	1997
International Journal of Applied Sustainable Development	2004	Sustainable Development UK	1997
International Journal of Arab Culture, Management and Sustainable Development	2008	Sustainable Development: Journal	1993
International Journal of Environment and Sustainable Development	2002	Sustainable Fisheries Livelihoods Programme Newsletter	2000
International Journal of Environmental, Cultural, Economic and Social Sustainability	2004	Sustainable Forest Management Network. Projects and Publications Guide	2001
International Journal of Innovation and Sustainable Development (IJISD)	2005	Sustainable Grazing on Saline Lands Network News	2004
International Journal of Low Energy and Sustainable Buildings	1999	Sustainable Humanosphere	2005
International Journal of Management and Sustainable Development	2005	Sustainable Industries Journal	2003
International Journal of Sustainability in Higher Education	2000	Sustainable Land Use Change in the Northwest Provinces of China. Research Reports	2004
International Journal of Sustainable Design	2007	Sustainable Urban Areas	2004
International Journal of Sustainable Development	1998	The Sustainable World Series	2002
International Journal of Sustainable Development and Planning: encouraging the unified approach to achieve	2005	Sustaining Regions	2001
International Journal of Sustainable Development and World Ecology	1994	Systems Approaches for Sustainable Agricultural Development	1992
International Journal of Sustainable Energy	2003	The International Journal of Sustainable Development and World Ecology	1995
International Journal of Sustainable Engineering	2008	The Journal of Sustainable Product Design	2001
International Journal of Sustainable Manufacturing	2007	The Journal of Sustainable Product Design: balancing economic, environmental, ethical and social issues in product design and development	1997
International Journal of Sustainable Manufacturing (IJSM)	2007	The McGill International Journal of Sustainable Development Law and Policy	2005
International Journal of Sustainable Strategic Management	2007	The Sustainable Times	1993
International Journal of Sustainable Transportation	2007	The Sustainable World	2002
International Journal of Technology Management and Sustainable Development	2002	Transport Canada. Entry Sustainable Development Strategy	1997
Journal of Chemistry for Sustainable Development	2000	Virtual Journal of Environmental Sustainability	2003
Journal of Asia Entrepreneurship and Sustainability	2005	Western Economic Diversification Canada. Sustainable Development Strategy	1997
Journal of Education for Sustainable Development	2007	What Works: An Annotated Bibliography of Case Studies of Sustainable Development	1993
Journal of Engineering for Sustainable Development: Energy, Environment, and Health	2006	World Journal of Sustainable Development	2006
Journal of Nature Science and Sustainable Technology	2006	World Review of Entrepreneurship, Management and Sustainable Development (WREMSD)	2005
Journal of Strategic Innovation and Sustainability	1999	World Review of Entrepreneurship, Management and Sustainable Development	2004
Journal of Sustainability Science and Management	2006	World Review of Entrepreneurship, Management and Sustainable Development	2005
Journal of Sustainable Agriculture	1990	World Review of Science, Technology and Sustainable Development	2004
Journal of Sustainable Agriculture: innovations for the long-term and lasting maintenance and enhancement of agricultural resources, production and environmental quality	1990	World Watch: working for a sustainable future	1988
Journal of Sustainable Development	2008

Sustainability definitions

	Year	Author	Synopsis
1	1946	Hicks	Amount one can consume during a period and still be as well off at the end of the period
2	1973	Holling	Multiscale, dynamic, hierarchical measure of resilience, vigour and organisation
3	1979	Coomer	Sustainable society is one that lives within the self-perpetuating limits of its environment. That society … is not a ‘no-growth’ society. It is, rather, a society that recognises the limits
4	1980	Allen	Utilise species and ecosystems at levels and in ways that allow them to go on renewing themselves for all practical purposes indefinitely
5	1989	Ruckelshaus	Interrelations of human beings and their works, the biosphere and the physical and chemical laws that govern it. It follows that environmental protection and economic
6	1984	Tietenberg	The sustainability criterion suggests that, at a minimum, future generations should be left no worse off than current generations
7	1985	Repetto	The greatest amount that can be consumed in the current period without reducing prospects for consumption in the future
8		Repetto	Live off the dividend of our resources, maintaining and improving the asset base, mix of human, physical, and natural assets, development demands the preservation of
9	1986	Burness	All processes operate only at their steady state, renewable level, which might then suggest a return to a regulated caveman culture
10	1986	Richard et al.	Food sufficiency; sustainability as stewardship; and sustainability as continuity
11	1986	Daly	Sustainability, like justice, is a value not achievable by purely individualistic market processes
12	1987	Pearce	The sustainability criterion requires that the conditions necessary for equal access to the resource base be met for each generation
13	1987	Goodland	Sustainable development implies using renewable natural resources in a manner which does not eliminate or degrade them, or otherwise diminish usefulness for future
14	1987	Brown	One in which humans can survive without jeopardising the continued survival of future generations of humans in a healthy environment
15	1987	Brundtland report	Meeting the needs of the present without compromising the ability of future generations to meet their own needs
16	1988	Pearce	Imply use of environmental services over very long time periods and, in theory, indefinitely
17	1988a	Turner	Conservation strategy, although its precise meaning and practical applications were not presented in a detailed and operational form
18	1988	Liverman et al.	Survival of human species through the maintenance of basic life support systems and the existence of infrastructure and institutions which distribute and protect the components
19	1988	O'Riordan	Survival of living matter to the rights of future generations and to institutions responsible for ensuring that such rights are fully taken into account in policies and actions
20	1988	Markandya and Pearce	The use made of these inputs to the development process through time. Apply the idea to resources, sustainability ought to mean that a given stock of resources
21	1988b	Turner	In principle, such an optimal policy would seek to maintain an ‘acceptable’ rate of growth in per-capita real incomes without depleting natural environmental
22	1998	Jeroen et al.	The Hicksian definition of income (Hicks, 1939): the maximum amount of income that can be spent without reducing real consumption in the future, social sustainability
23	1988	Conway and Barbie	The ability to maintain productivity, whether of a field or farm or nation, in the face of stress or shock
24	1990	Manning	Aspiration like happiness' or justice
25	1991	Daly	Rates of pollution emission do not exceed the assimilative capacity of the environment
26	1991	Robert	Moving from linear to cyclical processes and technologies. The only processes we can rely on indefinitely are cyclical, all linear processes must eventually come to an end
28	1992	Dower et al.	In order for a course of action to be sustainable it should be compatible with the local culture by respecting the structure of the society and values of the people
27	1992	Meadows et al.	Persist over generations, one that is far-seeing enough, flexible enough and wise enough not to undermine either its physical or its social systems of support
28	1992	Norton	Relationship between dynamic human economic systems and larger, dynamic, but normally slower-changing ecological systems, such that human life can continue
29	1993	Solow	Sustainability is an injunction not to satisfy ourselves by impoverishing our successors
30	1993	Pearce	Sustainable economic development is continuously rising, or at least non-declining, consumption per capita, or GNP, or whatever the agreed indicator of development is
31	1993	Hawken	Create objects of durability and long-term utility whose ultimate use or disposition will not be harmful to future generations. Change consumers to customers through education
32	1993	Beder	Economic growth could not continue on into the future without disaster, the principal defect of the industrial way of life with its ethos of expansion is that it is not sustainable
33	1994	DuBose	Sustainability does not describe a quality that resides within the confines of technology or practice but refers instead to the relationship between technology and context
34		DuBose	It is the nexus of relations between elements working in harmony that indicates sustainability – like an equation for which an answer cannot be derived from one variable
35	1994	Costanza	A sustainable scale of the economy relative to its ecological life support system; a fair distribution of resources and opportunities between present and future generations
36	1994	Liddle	Transformation of assets, reduction of wastes and improvement of energy efficiency
37	1995	Coop	Preserving the environment, developing strong peaceful relationships between people and nations and an emphasis on equitable distribution of wealth
38	1995	Starik and Rans	Ability of one or more entities, either individually or collectively, to exist and flourish for lengthy time-frames, in such a manner that the existence and flourishing of other
39	1995	Munasinghe	Making adequate provisions for the maintenance of biological diversity and maintaining the biogeochemical integrity of the biosphere by conservation
40	1997	Robert et al.	Concentrations of resources substances extracted from the Earth's crust, increasing concentrations of substances produced by society, impoverished by physical
41	1997	Ikerd	Sustainability is the broadest, most inclusive concept of environmental stewardship
42	1997	Lachman	Resources, politics, individual actions and the unique features of the community, ecosystem management, agriculture, biodiversity, green buildings, energy conservation
43	1998	Marcuse	Sustainability is not a goal; it is a constraint on the achievement of other goals
44	1998	Fricker	Survival is merely not dying, whereas we probably think of sustainability in terms of justice, interdependence, sufficiency, intuitive, the emotional, the creative and spiritual
45	1998	Cary	Not a fixed ideal, but an evolutionary process of improving the management of systems. Analogous to Darwin's species evolution, the process is non-deterministic with the end
46	1999	Sachs	Distinguishes between partial sustainability and whole sustainability. To realise whole sustainability
48	1999	Peacock	Sustainability is purely a matter of the management of scarce and ever-diminishing ‘negentropy’
49	1999	Pearce	Constraints are met, stakeholder satisfaction-basic needs met; resource base impact-no or neutral impacts; ecosystem impact-no or neutral impacts
50	2000	Oskamp	Sustainability may be defined as using the world's resources in ways that will allow human beings to continue to exist on Earth with an adequate quality of life
51	2001	Dorf	Living within a frame work of earths system, both thermodynamically and kinetically to maintain change
52	2001	Gibson	The protection of resources and ecological integrity over the long term, combined with great improvements in human well-being, especially among the poor
53	2001	Harris and Goodwin	Shift in perspective from a focus on economic development that is often defined as the expansion of consumption and GNP to a new view of sustainable development
54	2003	Parries and Kates	Normative judgments, such as goals and targets coded in formal agreements, treaties, and declarations, not in the form of semantic or philosophical clarification
55	2003	Johnston	Is as an ideal state of long-term social, economic and ecological stability, a target towards which we strive, rather than one we expect to reach
56	2005	Lebel	The relations between nodes in production consumption systems are shaped not only by economics and material flows, but also by culture, values, and power
57	2005	ESI	Sustainability is a characteristic of dynamic systems that maintain themselves over time; it is not a fixed endpoint that can be defined
58	2005	Hargrove and smith	Progress that improves economic social and environmental well-being with no major tradeoffs locally and globally, now and in the future
59	2007	Kajikawa et al.	Maintain something undiminished over some time period
60	2007	Australian Govt	Using conserving and enhancing resources
61	2007	Orecchini	Sustainable development does not consume resources; it uses and re-uses them, endlessly, closed cycles