Carbon tax policy has been shown to be an effective incentive for the reduction of carbon emissions, and it also profoundly influences supply chain cooperation. This paper explores the interaction between carbon taxes and green supply chain cooperation. Specifically, we analyze the impact of a carbon tax on green supply chain coordination and further optimize the carbon tax to achieve a win-win situation for both the supply chain and the environment. Because consumer’s behavior has a significant impact on green product demand, we consider the problems above under two types of consumer’s behavior characteristics: consumer’s environmental awareness and consumer’s reference behavior. A game-theoretic model is employed to describe a green supply chain consisting of a manufacturer and a retailer, combining important factors such as the carbon tax rate, green investment coefficient, and degree of reference effect. Then, we obtain the optimal carbon tax rate by balancing the total tax revenue and product greenness. A revenue-sharing contract is introduced to achieve green supply chain coordination, and the impact of the carbon tax on coordination is analyzed. The results show the following. (1) The carbon tax rate and the difference between the power of the manufacturer and retailer are the main factors determining green supply chain coordination. (2) Maximum greenness can be achieved when development costs are higher, while the maximum tax revenue is obtained when the development cost is lower, but with the loss of greenness. (3) If the power of the manufacturer is low, coordination can be achieved under the optimal carbon tax. If the power of the manufacturer is at a medium level, coordination can be achieved by increasing the carbon tax; as a result, increased greenness will be realized, but with the loss of tax revenue. However, when the power of the manufacturer is strong, coordination cannot be achieved. (4) Price reference behavior can promote supply chain coordination, but consumer’s environmental awareness cannot.
1. Introduction
With the degradation of the environment, increasing attention has been directed toward global warming. For sustainable development, many countries have been committed to reducing carbon emissions. For example, at the 2009 United Nations Climate Conference in Copenhagen, the Chinese government declared that carbon dioxide emissions per unit of GDP would be decreased by 40%–50% in 2020 compared with the levels in 2005 [1]. Carbon dioxide is widely emitted by the transportation and manufacturing sectors [2]. Carbon tax policy has been proven to be effective for emissions reduction [3–5], but it also exerts some side effects on enterprises [6]. From the perspective of the green supply chain, carbon tax policies imposed on an enterprise could decrease the profit within the supply chain, thus affecting supply chain cooperation. However, previous research [7–9] has mostly focused on decision-making and cooperation problems within the supply chain under a given carbon tax level, rather than considering the interaction between carbon taxes and supply chain cooperation. Therefore, it is important to examine the interaction between carbon taxes and supply chain cooperation.
Currently, to meet the requirements of carbon tax regulations, a growing number of enterprises have been striving for sustainability by committing to designing, producing, and promoting green products to reduce carbon emissions [10]. In this context, green products have been regarded as one of the important factors in achieving economic growth, energy conservation, and environmental sustainability [11]. Benjaafar et al. inferred that introducing carbon emissions into a supply chain optimization models can promote emissions reduction in the supply chain [12]. Meanwhile, carbon taxes increase production costs, thus imposing burdens on enterprises. Consequently, it has been increasingly challenging for governments to enact appropriate policies to reduce carbon emissions and improve supply chain performance at the same time [13]. In addition, consumer’s behavior is a crucial factor affecting product demand and sustainable decisions. In this study, we consider two types of consumer’s behavior characteristics: consumer environmental awareness (CEA) and consumer’s reference behavior. The former is an important factor that motivates firms to develop green products [14, 15]. The latter is a crucial factor that affects green product demand [16, 17]. In reality, many enterprises are concerned about carbon emissions, for example, HP, IBM, Ge, etc. They are not only beginning to design green products but also enhancing supply chain management and cooperation to achieve the goal of emission reduction. However, it is hard to achieve supply chain cooperation. Therefore, it is meaningful to study supply chain green decisions and cooperation considering consumer environmental awareness under a carbon tax policy. Therefore, we consider the interaction between the carbon tax rate and supply chain cooperation and optimize the tax rate in the context of CEA and consumer’s reference behavior. Specifically, we aim to answer the following questions:(i)Is carbon tax policy favorable for improving the greenness of products?(ii)Can carbon tax policy promote supply chain coordination to incentivize supply chain members to cooperate?(iii)Can carbon tax policy be beneficial for both product greenness and supply chain coordination simultaneously?
To investigate the above problems, a two-echelon supply chain is introduced. This is used to explore the interaction between green supply chain cooperation and carbon tax policy, where a manufacturer acts as the leader and determines the product’s greenness and wholesale price, and a retailer acts as the follower and determines the retail price of green products. Moreover, traditional products without green attributes (i.e., greenness) compete with green products in the market. Through consumer utility, we obtain the demand functions for both green and traditional products. In addition, the government decides the carbon tax rate to limit carbon emissions. Unit carbon emissions are associated with the greenness of products. The higher the greenness, the higher the product R&D cost, and the lower the unit carbon emission. Finally, the impact of the carbon tax on supply chain cooperation is analyzed by introducing a revenue-sharing contract.
The results show the following. (1) When the carbon tax and development cost are at high levels, the greenness increases with the carbon tax; otherwise, the greenness decreases with increasing carbon tax. Therefore, there exists an optimal carbon tax to maximize the greenness when the development cost is high. (2) Cooperation can be promoted when the government increases the carbon tax because the retailer plays a crucial role in coordination, and the region of cooperation is expanded when the carbon tax increases. (3) When the manufacturer’s power is relatively low, optimal carbon tax and supply chain cooperation can be achieved simultaneously, whereas when the manufacturer’s power is relatively high, cooperation cannot be achieved. In addition, when the manufacturer’s power is at a moderate level, cooperation can be achieved but with a loss of tax revenue in such a case.
The main contributions of this paper are as follows. We investigated a green supply chain cooperation problem and the interaction between carbon taxes and supply chain cooperation, taking consumer’s reference behavior into consideration, which fills a research gap in supply chain cooperation. Our result provides a reference for pricing and green product design and a meaningful reference for policymakers.
The remainder of this paper is organized as follows. A literature review is presented in Section 2. Section 3 introduces the basic assumptions and notations, and the supply chain model is formulated; then, the results of the model are analyzed, and we summarize the major conclusions of the numerical analysis. Finally, Section 4 summarizes the main research content and results.
2. Literature Review
Three streams of research are closely related to our work. First, we review the research on carbon taxes in green supply chains. Second, our work is related to research on reference behaviors in operational management. Third, relevant research on supply chain coordination is reviewed. Finally, we distinguish our study from the three streams of research mentioned above.
2.1. Carbon Tax
Reduction of greenhouse gas emissions is becoming a vital issue, and almost all developed and developing countries are now implementing policies for carbon emission reduction [18]. Numerous studies have focused on carbon taxes. Carbon taxes restrict the demand for fuels and thereby reduce the emissions of harmful greenhouse gases. Generally, carbon taxes are not always as high as possible. For example, a falling tax rate encourages manufacturers to produce and reduce emissions [19]. The optimization problem of carbon taxes has previously been studied [20]. Modak and Kelle integrated corporate social responsibility (CSR) investments into the supply chain strategy and operations and concluded that the optimal recycling rate and appropriate investment in recycling activities increase with an increase in the carbon tax rate [21]. There has also been other research regarding carbon taxes. For example, Ulph and Ulph analyzed the optimal time path for a carbon tax, and the numerical results suggested that a carbon tax should initially rise and then fall [22]. Kverndokk considered the optimal extraction of exhaustible resources and came to the same conclusion: the optimal carbon tax should initially rise and eventually fall [23]. Some scholars have suggested that the optimal tax should increase monotonically or follow a U-shaped pattern [24, 25]. However, the above studies did not consider the carbon tax in the context of a supply chain.
There are some research gaps in the studies on optimal carbon taxes for green supply chains. Most of the studies have focused on the decisions and cooperation problems of the supply chain under a carbon tax. Hariga et al. presented three operational models to determine the optimal lot-sizing and shipping quantities to reduce carbon emissions. In those experiments, a minor increase in operational cost with carbon tax regulation is outweighed by the cost savings resulting from carbon-related costs [26]. Turken et al. investigated the effect of environmental regulations in the form of a carbon tax on the plant capacity and location decisions of a firm. They proposed two novel policy options: (1) a per unit per mile transportation penalty and (2) a collective transportation emissions policy with a limit on total transportation emissions. Turken et al. also revealed that stricter regulations without high penalties would not ensure compliance, as the benefits from the increasing scale associated with a centralized plant frequently outweigh the regulatory penalties, and a per unit carbon tax had no effect on regional production of emissions [27]. Xu et al. investigated the joint production and pricing of a manufacturing firm with multiple products under cap-and-trade and carbon tax regulations. Their results showed that the optimal quantity of products produced under a carbon tax regulation is determined by the emissions’ trading prices and the tax rate [9]. Yu and Han studied the impact of a carbon tax on carbon emissions and retail prices in a two-echelon supply chain consisting of a manufacturer and a retailer. The results indicated that with an increase in the carbon tax, both the optimal emission reduction level and the optimal retail price initially increase and then remain stable [28]. Sinha and Modak developed an economic production quantity model that elucidates a new side of CO2 emissions reduction [29]. Zhang investigated the impact of the carbon tax on enterprise operation and obtained the coopetition supply chain and carbon tax mechanism [30]. Chen et al. investigated how a carbon emissions taxation scheme can be designed to reduce carbon emissions [31].
In general, there are two streams in the previous literature: the optimization of the carbon tax and the relationship between the carbon tax and operation decisions in the supply chain. However, there exists a research gap in the existing literature: few papers focus on the relationship between the optimal carbon tax and supply chain coordination. Our results show that by adjusting the carbon tax, the government can promote the coordination of supply chains and reduce carbon emissions. The optimal carbon tax policy to promote coordination between the supplier and retailer is obtained by balancing the tax revenue and the product greenness.
2.2. Consumer’s Reference Behavior
Consumers are always concerned about product value when choosing products on shelves. The final decision of consumption is a function of gains and losses with respect to a reference outcome [32]. Consumer’s reference behavior plays an important role in this process of comparison, thereby influencing firms’ operational decisions, such as product pricing and decisions regarding product greenness [33, 34].
Kopalle et al. studied a novel household heterogeneity translation model considering consumers’ price reference behavior and developed a normative pricing policy for retailers that maximizes category profit using individual-level estimates [35]. Hsieh and Dye investigated an inventory model based on price reference effects and established an optimal dynamic pricing model to determine a pricing strategy that maximizes the discounted total profit [36]. The results suggested that the strength of the memory factor is important for a retailer to measure because a high memory factor value represents consumers with a longer memory of perceived gains or losses. The optimal discounted total profit initially increases as the memory factor increases but decreases when the memory factor is relatively high. Some dynamic price studies have also considered price reference behavior [37, 38]. In these two previous studies, the price reference effect dominated the optimal pricing and inventory policy of the firm. The expected steady-state reference price was compared to the steady-state reference price in a model with a deterministic reference price effect, and the results showed that the former was always higher. Consumer’s environmental awareness is a common behavior in real life. At present, consumers are frequently concerned about environmental protection. Green preference and green product design have attracted extensive attention from scholars. Zhang et al. investigate the impacts of consumer environmental awareness and retailer’s fairness concerns on environmental quality [39]. Chen studied product design and marketing decisions based on consumer preferences for environmental attributes [40]. The development of green products depends heavily on the joint efforts of both the supply chain and the government. Therefore, the government should create a regulatory environment that is benign to green product innovation. Chitra inferred that green consumers affect marketing issues, and a preference for greenness will promote the purchase of green products [41]. The higher the consumer environmental preference is, the higher the price will be that the consumer is willing to pay for low-carbon products. Consumer’s green preference is in favor of supply chain performance on the environment [42]. Moreover, as competition intensifies, the profits of manufacturers with inferior eco-friendly operations will always decrease. Li et al. infer that consumers should avoid excessive pursuit of green product design; otherwise, they hurt the environment by investigating the impact of consumer preference for green product design [43].
Consumer’s reference behavior plays an important role in firms’ operational decisions, and consumer environmental awareness is a common behavior in real life. The literature above is about the influence of consumers’ green preference on enterprises’ decision-making, such as pricing and green manufacturing. There exists a gap in the existing literature, which is that the consumer’s behavior has not been concerned. In our research, the green preference and price reference behavior are considered.
2.3. Cooperation
Supply chain cooperation is defined as “long-term relationships where participants generally cooperate, share information, and work together to plan and even modify their business practices to improve joint performance” [44]. In general, supply chain cooperation means achieving better performance. In the supply chain, there are many coordination strategies to choose from, such as revenue sharing, buybacks, quantity discounts, and two-part tariff contracts. Among these contracts, revenue sharing has attracted the attention of many scholars and is widely used in actual supply chains [45]. For example, Xu et al. proposed a two-way revenue sharing contract to coordinate multiple distributors in a dual-channel supply chain, and the results showed that the manufacturer could prompt the retailer to cooperate by providing this contract [46]. Shi et al. studied reverse revenue-sharing contracts in a closed-loop system and proposed a function to calculate the optimal ratio of the transfer collection price. The results also suggested that reverse revenue-sharing contracts are more attractive for manufacturers than a two-part tariff [47]. Panda et al. explored channel coordination in a socially responsible manufacturer–retailer closed-loop supply chain and found that a revenue-sharing contract resolved channel conflict [48]. Modak et al. used the subgame perfect equilibrium and alternative offer bargaining strategy to resolve channel conflict and distribute surplus profit [49]. Wang and Zhao designed a revenue-sharing contract to reduce carbon emissions, and both the supplier and the retailer achieved Pareto improvement. In addition, they developed a function to determine the revenue sharing ratio using the Rubinstein bargaining model [50]. Yu et al. considered a cooperation problem in the low-carbon supply chain and found that the environmental awareness of consumers and tax rates considerably affect the emission reduction [51]. There have also been some supply chain coordination studies conducted under carbon policies. Revenue-sharing contracts have been designed to improve the performance of supply chain members based on different carbon policies [52]. Xu et al. studied the coordination problem in a two-echelon supply chain, and the effect of government policy-making on distributing the optimal emission quota was investigated. The results showed that a reasonable revenue-sharing contract is essential to increase supply chain members’ profits even under low-carbon conditions [53]. Modak et al. concluded that the optimal recycling rate increases with the CSR activity of the manufacturer, and a profit-sharing contract provides the best channel performance in a closed-loop distribution channel consisting of a socially responsible manufacturer, multiple retailers, and a third-party collector [54]. Feng infers that win-win results can be achieved by establishing profit-sharing contracts considering the preference of green consumers [55]. Previous papers often focus on two aspects, including the choice of contract and the conditions of the contract. However, the above literature still has a gap between cooperation and consumer’s behavior. Therefore, we investigate the supply chain cooperation problem under the context of consumer’s reference behavior and the carbon tax.
In summary, this study examines the interaction between supply chain cooperation and carbon taxes in a two-echelon supply chain considering consumer’s behavior. Some important factors should be considered simultaneously to study this problem, such as the optimal carbon tax and consumer’s behavior; however, previous research has only considered these factors separately. We also investigate the interaction between coordination and the carbon tax. The difference between our study and others in the literature is presented in Table 1.
Literature
Decisions under the carbon tax
Optimal carbon tax
Consumer’s behavior
Coordination
Yu and Han [28]
√
√
Ulph and Ulph [22]
√
Hsieh and Dye [34]
√
Cao et al. [47]
√
√
Xu et al. [48]
√
√
Our paper