1. Introduction

Researchers have discussed the “discursive struggles” to clarify the meaning of sustainable consumption, which have generated confusion among consumers and produced a “knowledge-to-action gap” in consumer behaviour ^[1]. Researchers have also identified and studied the “attitude–behaviour gap” that is reflected by the difference between attitudes towards sustainable consumption and actual purchase behaviours at retail stores ^{[2] [3] [4]}.

A wide field of research has emerged in relation to sustainable consumption behaviour, addressing topics such as the influencing factors of sustainable consumption and purchasing ^{[5] [6] [7]}, consumer perceptions ^{[8] [9]}, motivational drivers ^[10], attitudes towards sustainable consumption ^{[11] [12] [13]}, willingness to pay and its predictors ^{[14] [15] [16]}, and sustainable and pro-environmental purchasing behaviours ^{[17] [18] [19] [20]}.

Consumer engagement is considered an important concept for research in marketing and service management ^[21].  Two distinct streams have developed in this field ^[22]. The first considers the behavioural nature of customer engagement ^{[23] [24]} and the second considers the psychological nature of customer engagement ^{[25] [26]}. Researchers have focused primarily on consumer engagement in a virtual environment ^{[27] [28] [29]} and recently added an omnichannel perspective. Nevertheless, specialists have identified a “lack of research” on the theoretical meaning of consumer engagement in sustainable consumption and its empirical relationship with other relevant constructs ^[24].

A distinct field of research encompasses the role of retail in influencing consumers towards sustainable purchases and consumption. The research in this field is evolving, with the number of published articles experiencing an ascending trend. Despite this evolution, the academic literature lacks systematic reviews on this specific subject, a fact that underlines the need for such a review.

2. Consumer engagement in sustainable consumption

Recently, a new area emerged within the research literature about sustainable consumption. The new area encompasses studies on how retailers fulfil their role in engaging consumers in sustainable consumption. In this context, a research question must be answered: “In what context and by means of what marketing strategies, techniques, tools and channels does retail engage consumers in sustainable consumption?”.

The definition of the research question stems from the fact that consumer engagement is essential to support sustainable consumption and that retailers need to fulfil their role in engaging consumers in this direction. The buying and consumption decisions made by shoppers and consumers determine the content, intensity, directions, and costs of the flows of goods within the supply chains for consumer goods. Orientation towards sustainable consumption is not possible in the absence of rational and emotional support from the consumers’ side. The expected change towards sustainable consumption patterns will become a reality only if the behaviours of consumers, not only their attitudes and stated intentions, consistently indicate such an orientation.

A systematic literature review focused on this research question identified seven distinct types of retail marketing interventions (involvement of retailers in marketing actions with the aim to engage consumers in sustainable consumption), 30 types of retail marketing mechanisms (consisting in marketing strategies, techniques, tools, and channels used by retailers), and 14 distinct types of consumer engagement in sustainable consumption patterns ^[30].

3. Discussion

The findings of the systematic literature review mentioned above led to several discussion points, which are presented below.

The first point refers to the existence of similar ascending trends in research and business with regard to the engagement of consumers in sustainable consumption. Both the academic and business communities show increasing interest in this topic. The scientific literature reveals that scholars are devoting ever-greater attention to studying how retailers engage consumers in sustainable consumption. Thus, the academic research is in line with the emerging business practice focused on enhancing sustainable consumption. The different types of marketing interventions and marketing mechanisms applied by retailers to engage consumers in sustainable consumption are an integral part of a new trend in the practices of companies involving business-led sustainable consumption initiatives ^[31].

The second discussion point focuses on the growing interest shown by scholars and practitioners in the role of retailers as a new paradigm for thinking about the responsibilities to ensure sustainable consumption within the wider framework of the debate on sustainability topics. The role of developing sustainable consumption cannot be assigned to consumers only, making them responsible for putting pressure on producers and retailers to orient them towards sustainable production and offering ^[32]. Retailers must also play a major role due to their position in the supply chain at the interface with shoppers and consumers.

The third discussion point underlines the current development stage of the academic literature. The number of articles that were the object of this systematic literature review demonstrates that research literature on this topic is only at the beginning of its growth stage. The research on how retailers fulfil their role in engaging consumers in sustainable consumption has real development potential in the near future, in parallel with the increasing interest of researchers and practitioners in the wider domain of sustainable consumption.

The fourth discussion point relates to the available knowledge on the potential types of retail marketing interventions and mechanisms for consumer engagement. The findings of this review demonstrate that retailers can select from a relatively wide range of different types of marketing interventions and marketing mechanisms to fulfil their role in engaging consumers in sustainable consumption. The intermediary position held by retailers in the supply chains between producers/manufacturers and consumers will help retailers to drive sustainable consumption.

Ultimately, another discussion point underlines the consumer engagement stages explored by the relevant research. The definition of the sustainable consumption process encompasses three distinct stages—the acquisition, usage, and disposal of goods and services ^[33]. According to this systematic review, the different types of consumer engagement practices determined by the retail intervention and mechanism relate predominantly to the purchasing (acquisition) stage. The reviewed articles did not focus, as their main research topics, on the stages involved in the usage and disposal of goods for the marketing interventions of retailers.

4. Questions for further research

The findings of the systematic literature review, which were discussed in the section presented above, revealed that academic literature on how retailers engage consumers in sustainable consumption is only at the beginning of its growth stage. Based on the review findings, in-depth studies are necessary to answer ten crucial research questions:

• What is the most accurate definition of a retailer’s role in engaging consumers in sustainable consumption?
• How can systems thinking contribute to the identification of effective ways to engage consumers in sustainable consumption?
• What stages of the consumer engagement process are most critical to successful involvement in sustainable consumption?
• What would be the most reliable retail marketing mechanisms that are able to engage consumers in the sustainable consumption of specific product categories?
• How could retailers design a seamless omnichannel experience that is able to successfully engage consumers in sustainable consumption over the long-term?
• What marketing drivers can generate the highest level of retail involvement in engaging consumers with sustainable consumption?
• What factors influence the level of consumer engagement?
• What factors determine the duration of consumer engagement in sustainable consumption as a result of the retail marketing mechanism?
• What factors moderate the relationship between the marketing mechanism chosen by the retailer and the level of consumer engagement?
• What, and how, should retail marketers measure to evaluate the level of consumer engagement in sustainable consumption and the effectiveness of the retail approach?

These research questions underline the need for reliable and valid answers, as well as the numerous opportunities for further studies.