A Systematic Review of the Scope and Patterns of Green Consumption in Sub-Saharan Africa

: Despite the importance of “green consumption”, it has received little attention in sub-Saharan Africa. To address this gap, a systematic review of the scientiﬁc literature was conducted on the patterns of green consumption in this region using three parameters: green consumption, behaviour, and location. Forty-eight articles and publications were identiﬁed between 2010 and 2021 on Scopus, Web of Science, Google Scholar and grey literature. Scientiﬁc literature on green consumption in sub-Saharan Africa has expanded over the last ﬁve years, but it focuses primarily on emerging countries (Republic of South Africa and Nigeria) and the upper social classes. Most articles used the theory of planned behaviour as a theoretical framework. Green consumption of food and agricultural products are the most studied, with 14 articles. Energy, cosmetics, tourism, and textiles are each the subject of three speciﬁc publications. The emergence of middle-class consumers in sub-Saharan Africa is likely to contribute to the expansion of green consumption for a broad spectrum of goods and services.


Introduction
With climate change, biodiversity loss, and deforestation, companies are increasingly sensitive to global environmental issues [1]. These problems require the integration of environmental management into the management system of companies [2,3]. Taking the environment into account has become the mantra of companies wishing to expand their market share and have a competitive advantage in the global market [4]. As a result, an increasing number of companies are engaging in green production and adopting corporate social responsibility strategies [5].
Consumption patterns have also changed, and green consumption is developing throughout the world. Promoting green consumption is essential to achieving sustainable development [6,7]. We are witnessing the emergence of green consumption [8]. The global green consumption market has grown sevenfold in 20 years [9] and represents more than 4% of the food market [10].
Also called sustainable, ethical, or responsible consumption [4], green consumption consists of purchasing goods or services that meet individual needs, improving quality of life, minimising the use of natural resources and toxic materials, and reducing the amount of waste and pollutants throughout the life cycle of the service or product [11][12][13][14][15]. Green consumption behaviour has been the subject of numerous studies in developed countries over the past forty years [13,[16][17][18][19][20], and more recently in emerging economies [21,22]. Less developed countries, especially in sub-Saharan Africa, have not yet been significantly influenced by this phenomenon [23][24][25]. Some researchers have started to study the premises grey literature. After deleting duplicates, we were left with 1490 articles. Next, we read the abstracts and discarded 1372 papers which did not meet some of the inclusion criteria, such as geographical area or the main topic of the publication. Lastly, after reading the remaining 118 articles in full, we retained 48 studies from 2010 to 2021 that met the inclusion criteria ( Figure 1). 1600 studies were initially identified from Scopus, Web of Science, Google Scholar, and grey literature. After deleting duplicates, we were left with 1490 articles. Next, we read the abstracts and discarded 1372 papers which did not meet some of the inclusion criteria, such as geographical area or the main topic of the publication. Lastly, after reading the remaining 118 articles in full, we retained 48 studies from 2010 to 2021 that met the inclusion criteria (Figure 1).

Characteristics of the Studies
Given the heterogeneity of our database, we designed a qualitative synthesis for publications based on four variables: country, theoretical framework, sample size, product types, nature of respondents (Table 1). Theoretical framework shows the main theories used by the authors to analyse consumers' behaviour. Sample size indicates the representativeness of the study. The nature of the respondents gives an idea of the customers' patterns. The type of product makes explicit the sectors most influenced by green consumption.
We also drew out the main insights of each publication.

Characteristics of the Studies
Given the heterogeneity of our database, we designed a qualitative synthesis for publications based on four variables: country, theoretical framework, sample size, product types, nature of respondents (Table 1). Theoretical framework shows the main theories used by the authors to analyse consumers' behaviour. Sample size indicates the representativeness of the study. The nature of the respondents gives an idea of the customers' patterns. The type of product makes explicit the sectors most influenced by green consumption.
We also drew out the main insights of each publication. Environmental knowledge, environmental concern, and consumption values positively affect the intention to visit green hotels. Environmental knowledge and concern indirectly influence the intention to visit green hotels in terms of consumption value. Social influence, environmental concern, and price influence consumers' attitude towards green products. In turn, attitude has a positive impact on sustainable consumption behaviour. Being a woman has a greater influence on green purchasing behaviour and attitudes than being a man. Attitude, subjective injunctive norms, subjective descriptive norms, perceived behavioural control, altruism, and green self-identity have a positive and significant impact on consumer intention to choose green hotels. The partial mediating effect of attitude in the relationship between altruism and intention is significant.

Theory of planned behaviour
Organic care products 412 students Attitude, subjective norms, perceived behavioural control, moral norms, and ethical identity positively influence the purchase intention of organic personal care products. Environmental concern, social standards, and attitude significantly influence purchase intention. Attitude and price positively impact trust in environmental labels. Personal norms and attitude have a positive and significant effect on the purchase intention of non-plastic reusable bags while subjective norms negatively influence purchase intention. On the other hand, purchase intention has a significant and positive effect on the actual use behaviour of non-reusable plastic bags. Attitude, subjective norms, health have a significant impact on purchase intention for organic products. Perceived behavioural control has a weak influence on purchase intention in Kenya and is insignificant in Tanzania. Knowledge positively moderates the relationship between subjective norms, attitude, health concern, and intention to purchase organic food. Environmental concern, perceived usefulness, perceived ease of use, and affordability have a significant and positive impact on the attitude towards renewable energy consumption. Environmental concern, attitude, affordability positively influence purchase intention.

Classification of Selected Articles
• By Journal The 48 articles selected were published in 37 journals. Numerous scientific reviews discuss the topic of green consumption behaviour in sub-Saharan Africa, but only four journals published more than one article on the issue: Sustainability, Mediterranean Journal of Social Sciences, International Journal of Consumer Studies, and Journal of Cleaner Production, which published six, four, three and two articles, respectively, between 2010 and 2021.

• By the Nature and Number of Respondents Interviewed
The studies on green consumption behaviour were based on surveys involving three types of respondents: consumers, consumers and non-consumers, students and households. In our sample, four studies have less than 50 respondents, 20 studies have a sample size of between 51 and 399 respondents, 21 studies have a sample size between 400 and 999 respondents, and only one study has more than 1000 respondents. One article does not mention the size of their sample, but simply the geographical scope of their analysis.

•
By Sector The issue of green consumption behaviour is tackled in several economic sectors. Most relevant publications concern agriculture, which is covered in 14 studies. The circular economy is addressed in three studies, as well as natural resources and green technology and energy. Cosmetics, tourism, and textiles are each covered in three studies. Other sectors, such as marketing, construction, and natural resources appear in fewer publications on green consumption behaviour. In addition, seven studies discuss green consumption behaviour in general, without specifying the sectors concerned.

• By Country
A total of 44% of the publications in the systematic review focus on the Republic of South Africa (RSA), 23% on Nigeria, 10% on Ghana, and 4% on Cameroon, and Tanzania. Eight percent of the studies concern Burkina Faso, Ethiopia, Kenya and Tanzania, and Mauritius. However, 6% of the studies deal with green consumption behaviour in developing countries, but do not give any further details on the countries concerned.

• By Year of Publication
The articles included in the review date from 2010 to 2021. The number of publications on consumer behaviour has risen steadily, although the pattern has been uneven ( Figure 2). From the year 2020 onwards, the number of publications increased, reaching its highest level in 2021.

By Theoretical Frameworks
The majority of publications (57.14%) rely wholly or partly on Ajzen's theory of planned behaviour [80] to explain the relationship between the environment and consumer behaviour [26,34,43,49,51,57]. This theory is derived from Fishbein and Ajzen's theory of reasoned behaviour [80]. It states that green purchase intention is driven by three predictor variables: 1. Attitude, which reveals the favourable or unfavourable feeling an individual may have about a product [81]; 2. Subjective norms, which reflect the influence that society may have on an individual's consumption choice [81]; 3. Perceived behavioural control, which indicates an individual's view of the ease or difficulty of engaging in responsible behaviour.
In addition, the indirect and/or direct effect of these three behavioural variables are generally assessed by the notion of mediator and moderator. The mediator effect is a mechanism by which an independent variable influences a dependent variable through a so-called mediating variable. The moderator variable determines the strength of the relationship between two variables [65]. This model has been used by several authors [3,32,33,62]. For example, media campaigns, consumer confidence, and altruism can be mediating or moderating variables. In some studies, behavioural variables may also act as mediators [49,62].

Discussion: What Are the Prospects for Green Consumption in Sub-Saharan Africa?
This systematic review is the first ever to highlight the characteristics of green consumption behaviour in sub-Saharan Africa. It highlights the factors that influence green consumption choices and serve as a signal for companies to increase their competitive advantage.
Using Prisma's analysis method, we selected 48 articles for our study. The number of publications has increased over the past ten years and risen sharply since 2020. This topic appears to be generating more interest in the scientific world, a trend that is likely to continue in the coming years.
The number of economic sectors involved in green production is also increasing, although food remains the dominant sector.

• By Theoretical Frameworks
The majority of publications (57.14%) rely wholly or partly on Ajzen's theory of planned behaviour [80] to explain the relationship between the environment and consumer behaviour [26,34,43,49,51,57]. This theory is derived from Fishbein and Ajzen's theory of reasoned behaviour [80]. It states that green purchase intention is driven by three predictor variables:

1.
Attitude, which reveals the favourable or unfavourable feeling an individual may have about a product [81]; 2.
Subjective norms, which reflect the influence that society may have on an individual's consumption choice [81]; 3.
Perceived behavioural control, which indicates an individual's view of the ease or difficulty of engaging in responsible behaviour.
In addition, the indirect and/or direct effect of these three behavioural variables are generally assessed by the notion of mediator and moderator. The mediator effect is a mechanism by which an independent variable influences a dependent variable through a so-called mediating variable. The moderator variable determines the strength of the relationship between two variables [65]. This model has been used by several authors [3,32,33,62]. For example, media campaigns, consumer confidence, and altruism can be mediating or moderating variables. In some studies, behavioural variables may also act as mediators [49,62].

Discussion: What Are the Prospects for Green Consumption in Sub-Saharan Africa?
This systematic review is the first ever to highlight the characteristics of green consumption behaviour in sub-Saharan Africa. It highlights the factors that influence green consumption choices and serve as a signal for companies to increase their competitive advantage.
Using Prisma's analysis method, we selected 48 articles for our study. The number of publications has increased over the past ten years and risen sharply since 2020. This topic appears to be generating more interest in the scientific world, a trend that is likely to continue in the coming years.
The number of economic sectors involved in green production is also increasing, although food remains the dominant sector.
Although the number of publications on green consumption in sub-Saharan Africa is growing, the number of green consumers remains limited. More than half of the publications focus on the RSA and Nigeria, the two largest economies in sub-Saharan Africa. These two countries are often referred to as "emerging countries" and, therefore, they are not necessarily representative of the economic situation in most African countries.
In addition, irrespective of the African country studied, the purchase of green products only concerns the upper-or extreme upper-fringe of the population, i.e., the wealthy and/or well educated [49,60,61]. The latter are more aware of the impact of responsible consumption and its virtues for health. The urban middle class, which is growing in sub-Saharan Africa, is not very aware of the issue [64,78]. In Africa, the working classes are still the majority in terms of sheer numbers, but their situation (poverty and lack of education) means that meeting their basic needs at the lowest cost is their main priority, rather than the environment [46,82].
Several studies demonstrated that the motivation to pay for green products was driven by attitude, subjective norms, and perceived behavioural control that positively impact the purchase intention of green products [32,43]. Some authors have gone further by providing an extension field to the theory of planned behaviour by adding some variables such as altruism, anxiety, knowledge, loyalty [46,57,61]. In sub-Saharan Africa's economic context, where the vast majority of consumers have a limited budget, the pertinence of the theory of planned behaviour is debatable. Other variables besides attitudes, subjective norms, and perceived behavioural control determine the volume and type of consumption, such as social and economic variables (income level, gender, geographical origin, cultural background, etc.). For example, in a study, [54] came to the conclusion that gender positively influences the behaviour of visiting sustainable infrastructure in cities, especially among men. Similarly, [76] assessed a positive influence between gender and consumption behaviour. In addition, the study of [2] showed a positive relationship between consumer confidence and green consumption behaviour. Thus, a green marketing policy is essential to stimulate consumer confidence which will act directly on green purchasing behaviour. One perspective would therefore be to identify thresholds in terms of national economic development and individual income to optimise the explanatory and predictive power of the theory of planned behaviour.
Despite the relevance of this study, it has some limitations. The systematic review exercise is based on algorithms which were tested and readjusted many times to obtain a coherent and reliable list of scientific articles related to the topic, geographical area, and time period. However, this standardized analysis has three limitations. First, it must be supplemented by a non-automated review of technical reports and more "grey literature", which are not published by the major private scientific publishers. This complementary review is inevitably partial, especially because it concerns an original field of study, where recent advances may not have been the subject of formal scientific publications. This is the case, for example, with participatory guarantee systems, which have developed rapidly in recent years [83], and are often based on small-scale forms of responsible consumption.
Second, the low number of articles is a limitation. Indeed, the last search was done in November 2021, so the articles from 2022 and 2023 are not among our selected articles. Moreover, the geography of the study means that we also have fewer articles.
Third, the systematic review revealed the diversity of green consumption patterns in sub-Saharan Africa, despite the dominant use of the theory of planned behaviour framework. For instance, several factors related to cultural heterogeneity explain the diversity of green consumption behaviour in this region and in different sectors, although the systematic review was unable to make them explicit.

Research Direction
Our results show that the emergence of green consumption in sub-Saharan Africa does not depend on a single factor, but on several other factors that jointly determine consumer behaviour. This paper provides an overview of the factors influencing green consumption behaviour to researchers who want to contribute to the emergence of green products in developing economies. Through further analysis of the factors and their correlation on the purchase of green products, researchers can determine the factors that most influence green consumption for a well-defined sector through a quantitative or quantitative analysis.
Based on these results, they can propose sustainable policies to further stimulate this consumption, while controlling the factors that risk negatively impacting this consumption.
Interdisciplinary studies that integrate insights from psychology and economics should also be explored [84] in the context of new behavioural economics models. The acceleration in 2019 in the number of publications devoted to green consumption behaviours in sub-Saharan Africa draws on a wide range of research models published in various journals. Our study shows a predominance of the planned behaviour model. In the case of developing countries, a threshold in terms of national economic development or individual income should be established to see the effects of the theory of planned behaviour, which could be an avenue to explore for future research.
Future studies can use complementary theoretical frameworks such as self-determination theory [85] that could be useful in conceptualizing the origin of the precursors to theory of planned behaviour by bringing the concept of motivation into play [86,87]. Another avenue would be to use prospect theories that link psychological and economic prescriptions within the framework of behavioural economics [88]. Finally, future research can rely on experience-based methodological tools, as suggested by new models in behavioural economics [89].

Conclusions
The protection of the environment is a global concern. Faced with this situation, the demand for green products is on the rise, which has sparked interest in this subject in the research community. Green consumption is growing rapidly in sub-Saharan Africa too, but with greater expansion in emerging countries, such as South Africa and Nigeria. Moreover, its socio-economic scope is limited because only the upper classes can afford to pay for green products. The emergence of the middle classes is likely to be a major turning point in the expansion of green consumption in the region. The medium-term challenge is to raise awareness about responsible consumption among a less wealthy target audience, by developing approaches that are not necessarily linked to a higher level of income or education.
"buy* attitude*" OR "consum* intention*" OR "purchas* intention*" OR "buy* intention*" OR "consum* decision*" OR "purchas* decision*" OR "buy* decision*" OR "consum* value*") AND (green* OR environment* OR proenvironment* OR sustainab* OR ecolog* OR biodiversit* OR organic* OR natur* OR responsib* OR ethic* OR moral* OR fair* OR conscious* OR "eco-friendly" OR certified OR label* OR renewab* OR clean* OR wast* OR recycl* OR pollution* OR energy OR food* OR water* OR climat* OR carbon* OR ecosystem* OR agricultur* OR forest*)) OR (("green* behavior*" OR "environment* behavior*" OR "proenvironment* behavior*" OR "environment* friendly behavior*" OR "sustainab* behavior*" OR "ecolog* behavior*" OR "responsib* behavior*" OR "recycl* behavior*" OR "green attitude*" OR "environment* attitude*" OR "environment* responsib*" OR "social* responsib*" OR "environment* concern*" OR "environment* conscious*" OR "environment* value*" OR "environment* self-identity" OR "environment* identity" OR "sustainab* practice*") AND (consum* OR purchas* OR buy*))) AND ("sub saharan africa" OR "south africa" OR rsa OR angola OR benin OR botswana OR "burkina faso" OR burundi OR cameroon OR "ivory coast" OR ethiopia OR gabon OR gambia OR ghana OR guinea OR kenya OR lesotho OR liberia OR madagascar OR malawi OR mali OR mauritius OR mauritania OR mozambique OR namibia OR niger OR nigeria OR uganda OR "central african republic" OR congo OR drc OR rwanda OR senegal OR "sierra leone" OR somalia OR sudan OR swaziland OR tanzania OR chad OR togo OR zambia OR zimbabwe)).
We used the following algorithm in the Web of Science: TOPIC: ("green consumption" OR "sustainable consumption" OR "responsible consumption" OR "ethic consumption" OR "energy consumption" OR "green purchase" OR "green market" OR "green product" OR "sustainable products" OR "environment friendly product" OR "eco-friendly product" OR "environment market" OR "sustainable market") AND TOPIC (behavior OR attitude OR intentio OR decision) AND ADDRESS: ("sub saharan africa" OR "south africa" OR rsa OR angola OR benin OR botswana OR "burkina faso" OR burundi OR cameroon OR "ivory coast" OR ethiopia OR gabon OR gambia OR ghana OR guinea OR kenya OR lesotho OR liberia OR madagascar OR malawi OR mali OR mauritius OR mauritania OR mozambique OR namibia OR niger OR nigeria OR uganda OR "central african republic" OR congo OR drc OR rwanda OR senegal OR "sierra leone" OR somalia OR sudan OR swaziland OR tanzania OR chad OR togo OR zambia OR zimbabwe).