Are climate change perceptions related with plastic policy support? Effects of climate change skepticism, guilt, and efficacy on the acceptance of the plastic tax

PLOS One | https://doi.org/10.1371/journal.pone.0337327 December 29, 2025 1 / 30 OPEN ACCESS Citation: Kim M, Kim S, Jeon S (2025) Are climate change perceptions related with plastic policy support? Effects of climate change skepticism, guilt, and efficacy on the acceptance of the plastic tax. PLoS One 20(12): e0337327. https://doi.org/10.1371/journal. pone.0337327 Editor: Baogui Xin, Shandong University of Science and Technology, CHINA Received: April 17, 2025 Accepted: November 6, 2025 Published: December 29, 2025 Peer Review History: PLOS recognizes the benefits of transparency in the peer review process; therefore, we enable the publication of all of the content of peer review and author responses alongside final, published articles. The editorial history of this article is available here: https://doi.org/10.1371/journal. pone.0337327 Copyright: © 2025 Kim et al . This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, RESEARCH ARTICLE Are climate change perceptions related with plastic policy support? Effects of climate change skepticism, guilt, and efficacy on the acceptance of the plastic tax Miri Kim1, Seoyong Kim 2*, Sehyeok Jeon3 1 Research Institute for Future Safety Policy, Ajou University, Suwon, Republic of Korea, 2 Department of Public Administration, Ajou University, Suwon, Republic of Korea, 3 Research Institute for Future Safety Policy, Ajou University, Suwon, Republic of Korea * seoyongkim@ajou.ac.kr Abstract

Achieving a circular economy requires solutions to plastic pollution problems. Plastic waste poses significant threats to both human and biological systems globally. Plas- tics are closely related to climate change because their production is based on fossil fuels. Plastic taxation is one approach to reducing plastic use. This study aimed to analyze how the climate change perception is related to the preference for plastic tax. A model was developed to examine the impacts of 11 variables in value, risk percep- tion, and planned behavior acting as predictors on the support for plastic tax as the predicted variable. In particular, we focused on both direct and indirect association of the three variables in planned behavior, that is, climate skepticism, guilt, and efficacy about climate change crisis, on support for the plastic tax. The results showed that among value variables, environmentalism, altruism, and egalitarianism had a signifi- cantly positive relationship with the willingness to pay the plastic tax and materialism had a significant negative relationship. Regarding risk perception, perceived risk, knowledge, and trust had a significantly positive association with the willingness to pay the tax. Regarding planned behavior, skepticism, guilt, and efficacy had a significant association with willingness-to-pay the plastic tax, with climate change skepticism having a negative effect and guilt and efficacy having positive relationship. Regarding the moderation effect, skepticism had an interaction effect on materialism

and emotion; guilt is associated with the impact of environmentalism, altruism, egali- tarianism, perceived risk on the support for plastic tax; and efficacy is associated with the association of altruism and perceived risk with preference for plastic tax. These results suggest that climate change risk perception is associated with plastic reduc- tion behaviors.

PLOS One | https://doi.org/10.1371/journal.pone.0337327 December 29, 2025 2 / 30 Introduction Plastic waste is occupying every corner of the planet. To analyze the factors that determine support for taxes to reduce plastic use, this study used climate change- related factors (e.g., skepticism, guilt, and efficacy) as key predictors, specifically evaluating their moderating effect on tax acceptance. This study is necessary for three reasons. First, climate change and plastic waste issues are closely interconnected. Plastics are made from fossil fuels, and increased production results in increased greenhouse gases. Global plastics production reached 390.7 million metric tons in 2021, a 4% annual increase [1]. According to U.S. Beyond Plastics (October 2021), plastics will contribute more to climate change than coal-fired power plants by 2030 [2]. At least 14 million tons of plastic accumulate in oceans annually, with microplastics destroying marine ecosystems that help allevi- ate climate change effects [3]. Plastic pollution has reached unprecedented levels, with approximately 380 million tons produced annually [4], of which only 9% is recycled while 79% accumulates in landfills or natural environments. Marine ecosystems are particularly affected, with 11 million metric tons entering oceans annually [5], projected to triple by 2040 with- out intervention [6]. The plastic industry accounts for approximately 4–8% of annual global oil consumption [7], with greenhouse gas emissions potentially reaching 2.8 billion tons annually by 2050 [8].

Second, plastic tax introduction is garnering growing worldwide support. The Euro- pean Union imposed a 0.8 euros per kilogram tax on non-recyclable plastic waste from January 2021 (Decision (EU) 2019/665). Italy became the first EU country to announce plastic tax at €1 per kilogram in 2020, targeting companies and consumers [9]. Indonesia also introduced plastic tax to address environmental damage. While US implementation faces challenges due to cost concerns for companies and con- sumers, understanding support levels for plastic tax legislation remains important. Third, research on plastic tax implementation and human behavior effects is limited. Recent studies demonstrate significant behavioral impacts: Rivers et al. [10] found plastic bag taxes reduced consumption by 53–80% in Canada, while Homonoff et al. [11] documented substantial changes from small taxes on single-use bags. Taylor et al. [12] observed that plastic bag taxes were more effective than equivalent subsidies for eco-friendly alternatives. However, as plastic tax is new and previ- ously unlevied, implementation research remains scarce. Despite increasing climate change policy importance, consumer plastic tax support research is limited, with plas- tic research focusing mainly on recycling technologies and eco-friendly materials [13]. This study explores how three factors (risk perception paradigm, value, planned behavior) associate with plastic tax support. The conceptual foundation linking climate change perceptions to plastic tax sup-

port rests on three integrated theoretical frameworks. First, Values-Beliefs-Norms (VBN) theory demonstrates that environmental values associate with policy support through awareness of consequences [14], with stronger environmental values cor- relating with greater climate policy support [15]. Second, Theory of Planned Behavior and reproduction in any medium, provided the original author and source are credited. Data availability statement: The data that support the findings of this study are feely available from https://doi.org/10.6084/ m9.figshare.28735508.v2. Funding: This work was supported by the Ministry of Education of the Republic of Korea and the National Research Foundation of Korea (NRF-2021S1A5C2A02087244). The Human Resources Development Project for HLW Management hosted by KORAD and MOTIE. Competing interests: The authors have declared that no competing interests exist.

PLOS One | https://doi.org/10.1371/journal.pone.0337327 December 29, 2025 3 / 30 (TPB) suggests attitudes, subjective norms, and perceived behavioral control influence behavioral intentions [16]. Climate change skepticism significantly moderates environmental policy support [17], while guilt motivates pro-environmental behaviors when individuals perceive personal climate responsibility [18]. Third, risk perception paradigm indicates that perceived climate risks drive mitigation policy support [19], with higher climate risk perception correlating with increased environmental regulation support [20]. The link between climate change perceptions and plastic tax support emerges from plastic production’s connection to greenhouse gas emissions, with plastic lifecycle contributing approximately 4–8% of global emissions [21]. Citizens per- ceiving climate change as serious risk more likely support emission-targeting policies, including plastic taxation [22]. Environmental policy acceptance requires multi-paradigm integration because single theories systematically under- predict behavior, explaining only 19–39% of variance [23]. Integration is theoretically necessary because environmental policies activate multiple psychological systems simultaneously. Values determine what risks matter [24], risk perceptions shape policy attitudes [25], and behavioral intentions require perceived control and normative support [16]. Combined models explain 52–58% of environmental behavior variance compared to 27–39% for single theories [26].

Our study focuses on plastic tax rather than direct prohibitions because economic incentives are often more effective for behavioral change. Rivers et al. [10] explained that taxes are more cost-effective than mandatory bans and generate less social resistance. Additionally, taxation represents an integrative approach affecting both consumers and producers [27]. We examined both direct and indirect impacts of skepticism, guilt, and climate change efficacy on plastic tax prefer- ence, particularly focusing on moderating roles within TPB. The moderation role of planned behavior factors is theoretically grounded in TPB extensions. Climate change skepti- cism functions as a cognitive filter moderating value-behavior relationships through motivated reasoning [24], with skep- tical individuals selectively processing information to confirm existing beliefs [28]. Guilt’s moderating role is supported by affective-cognitive interaction theories, where emotional states amplify cognitive processing [29], enhancing relationships between environmental concerns and behavioral intentions [23]. Self-efficacy’s moderation reflects social cognitive theory predictions that efficacy beliefs determine whether environmental values translate into behavioral intentions [30], strength- ening value-behavior relationships by increasing confidence in meaningful contributions [31]. Literature review The state of plastic world and public policy During the COVID-19 pandemic, there has been a rapid increase in the use of plastics, which are a major source of

greenhouse gas emissions. A prolonged pandemic would have led to graver environmental issues. The use of plastic during that period skyrocketed to the point that a new phrase, “corona trash,” was coined. For example, the Korea Envi- ronment Agency compared the amount of plastic trash produced in 2020, when the pandemic began, with that in Febru- ary 2022, and found that it increased 2.14 times, with a recycling rate of 68.1%, which was rather low compared to the increasing amount of plastic used. In addition, the emergence of microplastics has increased plastic pollution. According to United Nations Environment Program [32], in the early 2000s, the amount of plastic waste produced rose more in a single decade than it had in the previous 40 years. Global production of primary plastic is expected to reach 1,100 million tons by 2050. The level of greenhouse gas emissions related to the production, use, and disposal of conventional fossil fuel-based plastics is esti- mated to account for 19% of the global carbon budget by 2040. Plastic waste is now transforming into microplastics, which threaten natural and human ecosystems. A 2019 study by a team of researchers at Newcastle University in Australia, supported by the World Wide Fund for Nature [33], found that the average weekly per capita intake of microplastics is 5 grams. This means that microplastics are found in tap water, bottled water, streams, lakes, rivers, and oceans, in addition to the living environment and seafood worldwide.

PLOS One | https://doi.org/10.1371/journal.pone.0337327 December 29, 2025 4 / 30 Thus, more stringent policy measures are needed to regulate plastics. Accordingly, an international convention to reg- ulate plastics is expected to be introduced in 2024, leading to stricter steps taken by major countries to regulate plastics. Many countries have increasingly regulated plastics, including the EU that imposed a plastic tax and phased out single-use plastics starting in 2021. It has implemented the Ecodesign Directive for almost all products, and is working on a legislation in which 0.8 euros per kilogram of plastic waste from domestic packaging will be paid to the EU, with 25% recycled content being required in plastic bottles by 2025 and 30% or more by 2030. The United States has banned single-use products such as plastic bags at the state level, China has banned the nationwide production and sale of single-use plastic products since 2021, and Japan is promoting the use of bioplastics with a goal of achieving 100% recy- cling by 2035. The United Kingdom has imposed a recycled plastic tax of about 300 won per kilogram, depending on the percentage of recycled content in the plastic. A plastic tax is levied on non-recyclable plastic waste, and is being promoted to curb plastic use and promote the devel- opment of recyclable plastics. Because plastic taxes are emerging as the second trade barrier after carbon border taxes, it is necessary to discuss plastic taxes imposed worldwide. Imposing a plastic tax would contribute to solving the plastic

waste problem, but it would be a financial burden on businesses and individuals, which makes acceptability a key issue. In terms of economic logic, plastic taxes can have regressive effects, disproportionately impacting lower-income households. Rivers et al. [34] found that environmental taxes create a higher relative burden on lower-income households who spend a larger proportion of their income on consumption goods. The financial impact varies with price elasticity. Homonoff et al. [11] demonstrated that plastic bag taxes reduced consumption by 40%, but elasticities differ across plastic product catego- ries and household income levels. Economic modeling by Alpizar et al. [35] indicates that plastic taxes averaging 15–20% of product price can reduce household plastic consumption by 35%, but may increase household expenses by 1–3% annually, with lower-income households experiencing the higher percentage increase. While plastic taxes create economic incentives for reduced consumption [10], direct interventions may yield more immediate impacts. Poortinga et al. [36] demonstrated that a plastic bag charge combined with environmental messaging produced significant behavioral changes, reducing bag usage by over 90%. Similarly, Nielsen et al. [22] found that social norm interventions combined with behavioral nudges effectively reduced single-use plastic consumption independently of price mechanisms. However, it acknowledges that implementing a plastic tax would increase prices for plastic products, potentially creating

inequality issues and affecting critical sectors like healthcare. As Lee et al. [37] noted, medical instruments rely on plastics for material integrity and hygiene reasons [37]. During crisis periods like the COVID-19 pandemic, a plastic tax without exemptions could impede medical supply access, disproportionately affecting vulnerable populations. In the other hand, it considers the theoretical distinction between supporting regulatory policy versus engaging in per- sonal plastic reduction behaviors. As Stern [14] distinguishes, environmental citizenship behaviors (like supporting taxes) differ from private-sphere behaviors (like reducing personal plastic use). Future research should investigate whether climate change awareness predicts both policy support and direct plastic reduction behaviors. Three competing paradigms for explaining the attitude toward climate change Recent studies have expanded understanding of psychological mechanisms in environmental behaviors. Zhang et al. [38] demonstrated how cultural values influence low-carbon behaviors through perceived value mediation, providing prec- edent for examining value-behavior relationships in environmental policy contexts. Liu et al. [39] established manage- ment practices as mediators in green organizational behavior, paralleling our planned behavior factors as mediators between values and policy support. Zhang et al. [40] showed nature connectedness mediating outdoor activities and well-being, contrasting our climate perception focus while reinforcing environmental connection importance. Dai et al.

[41] explored identity as mediator in tourism contexts, supporting our multi-pathway approach to environmental policy acceptance.

PLOS One | https://doi.org/10.1371/journal.pone.0337327 December 29, 2025 5 / 30 However, very few models explain the public response to plastic tax. We assumed that plastic taxes are associated with attitude and behavior toward climate change because plastics are closely linked to fossil fuel production, which results in climate change. The dominant explanatory theories of climate change-related behavior can be divided into value, risk perception, and planned behavior theories. First, value theory recognizes that values play a key role in shaping individual attitudes toward environmental issues. Values are the fundamental orientations of individuals that are associated with their attitudes and behaviors. For example, the Values-Beliefs-Norms (VBN) theory proposed by Stern [14] explains pro-environmental behavior based on the three concepts of values, beliefs, and norms, and suggests selfish values, altruistic values, and ecological values as anteced- ents. According to VBN theory, values can be defined as ideas that regulate and influence human behavior; specifically, values determine individual beliefs and attitudes and are ideologies and principles that individuals, groups, and societies consider important [42]. Plastic use is linked to human habits. Changing habits requires a fundamental shift in our value system. From this perspective, examining the relationship between human values and plastic tax is necessary. Second, the risk perception paradigm has been widely studied in the context of risky objects, such as nuclear energy.

The risk perception paradigm, also known as the psychometric paradigm, was first discussed by Fischhoff et al. [43]. The risk perception paradigm is characterized by assuming risk as a subjective concept, with risk criteria including social and psychological aspects. It emphasized the importance of perception structures in risk judgment, and scholars focused more on evaluating public consciousness [44–46]. Previous studies have also analyzed risk perception in the context of climate change and global warming [47–49]. This study considers risk perception variables, such as perceived risk, knowledge, government trust, and emotion, as independent variables to determine the acceptance of the plastic tax. Third, this study examined the direct and indirect roles of skepticism, guilt, and climate change-related efficacy. All three variables were derived from the theory of planned behavior (TPB) developed by [16,43,50]. TPB, one of the widely used theories to study the relationship between intention and action, assumes that the most important factor in determining “action” is “intention” [51]. Ajzen [16] acknowledged that not all intentions led to action and that intentions were frequently abandoned, or some were modified to respond to the situation. After conducting a meta-analysis of studies related to the theory of reasoned action and TPB, Sutton [52] stated that the reviewed theoretical models could explain approximately 40–50% of intention on average; however, the explanatory power was decreased to 19–38% when the intention is

followed-up with the intended behavior. TPB is the most popular model used to explain human behavior in the context of climate change [31,53,54], demonstrating that the negative or positive attitude, norm, and climate change-related efficacy are associated with the response to climate change. We aim to further analyze how the three variables derived from TPB—that is, climate change skepticism, guilt, and efficacy—play a role in the relationship between value/risk perception and support for the plastic taxes. This analysis can address the question of whether climate change awareness can drive the acceptance of tax for plastic reduction policies. Values factors Environmentalism. With the increasing environmental crisis, the importance of environmental values has been acknowledged, and interest in environmentalism as an alternative has increased with an amplification of the harmful effects of environmental crisis. Environmentalism encompasses all philosophies, ideologies, and social movements that strive to protect the environment and promote environmental welfare, mainly in terms of preserving or restoring the natural environment. Environmentalism has a negative impact on the acceptance of risky objects (e.g., nuclear energy or climate change). Spence [55] found a negative relationship between climate change concerns and nuclear energy acceptance, with envi- ronmental concerns reducing support for nuclear energy. Park et al. [56] found that environmentalism was statistically

significant in the acceptance of energy price support policies for low-income households. Mozumder [57] found that environmental consciousness has a significant effect on the support for renewable energy. In addition, individuals who

PLOS One | https://doi.org/10.1371/journal.pone.0337327 December 29, 2025 6 / 30 possessed environmentalist values supported behaviors and policies related to environmental protection [58]. The relationship between environmental values and plastic consumption has been well-established by Heidbreder et al. [27], who demonstrated that pro-environmental values significantly predict reduced plastic consumption and support for plastic reduction policies. Because plastic is one of the risky objects such as nuclear power, we propose the following hypotheses. Hypothesis 1. Higher environmentalism is associated with higher acceptance of the plastic tax. Altruism. The VBN theory proposed by Stern [14] explains eco-friendly behavior based on three concepts, and divides values into altruistic, selfish, and ecological values. Altruistic values are pro-social values that focus on others rather than oneself, recognizing that individuals are interrelated to others. Whereas, egoistic values focus on personal success or wealth accumulation, which means that all thoughts and interests are focused on the self and not on others [59,60]. Ecological value refers to the value of the environment or ecosystem, rather than that of the individual or others, and prioritizes the preservation of ecosystems over humans. Jang et al. [61] showed that altruistic value orientation influenced the intention to purchase eco-friendly food products; in particular, the influence of altruistic value was more than that of

individualistic or ecological values. As altruism is more likely to lead to favorable attitudes toward climate change, it can lead to negative attitudes toward plastic taxes. Hypothesis 2. The higher the level of altruism, the higher acceptance of the plastic tax. Egalitarianism. Douglas et al. [62] consider cultural theory crucial for explaining risk perception and the risk perception paradigm. Cultural theory seeks to explain how people perceive the world and act, and the way an individual perceives the world is determined by the way they live [63]. Cultural values consist of egalitarianism, hierarchy, individualism, and fatalism, and influence the attitudes of individuals [62]. Among the four values, egalitarianism has a strong degree of collectivization, but aims for equality among group members, and the external regulation of individual lives is rather weak. For egalitarians, nature is easily damaged, so they are sensitive to new technologies and environmental issues that may change the state of nature or pose irreparable risks to future generations. In addition, they demonstrate a negative attitude about the exercise of power by experts or institutions. Kahan et al. [24] found that individuals with individualistic values tend to be skeptical about risks such as global warming, while those with egalitarian values tend to agree with the view that global warming is a risk. In other words, because egalitarians are more sensitive to risk issues, they are more likely to be willing to pay the plastic tax to address climate change.

Hypothesis 3. Higher egalitarianism is associated with a higher acceptance of the plastic tax. Materialism. Inglehart [64] explains that the advent of industrialized democracies has led to a shift from materialism to post-materialism by satisfying the most basic values and needs of economic growth and consumption [65]. In other words, while the satisfaction of physiological needs for human survival and the need for safety are directly related to materialism, the values that are pursued after materialistic values are largely realized are dematerialistic values, which are directly related to self-actualization and the main features of the community [66]. According to Kim et al. [65], environmentalism is a value that is mainly discussed in developed countries, and environmentalism boils down to the value of satisfying higher-order needs. Consequently, dematerialization has a positive effect on environmentalism and environmental behavior [67]. Materialistic values represent an important antecedent of attitudes within the TPB model, as evidenced in research by Hurst et al. [68], who demonstrated through meta-analysis that materialism negatively correlates with environmental atti- tudes and behaviors. Similarly, Ku [69] found that materialistic values significantly predicted less environmentally friendly behaviors. As Kilbourne et al. [70] argue, materialistic values predispose individuals toward attitudes that are less support- ive of environmental policies, which directly relates to the attitude component of TPB.

PLOS One | https://doi.org/10.1371/journal.pone.0337327 December 29, 2025 7 / 30 In this study, we assume that the lower the level of materialism, the higher the level of support for the plastic tax, which implies an increased awareness of the fragility of nature and can be viewed as a corresponding behavioral intention to protect the environment. Hypothesis 4. The lower the materialism, the higher acceptance of the plastic tax. Risk perception paradigm Perceived risk. Perceived risk, one of the most powerful variables in terms of acceptability in risk research, refers to the subjective evaluation and perception of risk. According to Slovic et al. [71], perceived risk reflects various social and psychological factors such as uncertainty and controllability of risk, and focuses on how risk is perceived. In particular, compared with perceived benefits, perceived risk plays an opposing role in acceptability. Visschers et al. [72] found that perceived benefits and perceived risks were opposite and significant for acceptance. For renewable energy, similar to nuclear energy, perceived benefits have a positive effect on the support for renewable energy, while perceived risks have a negative effect [73]. Kim et al. [74] found that the higher the perceived risk of climate change and perceived benefits of climate change mitigation, the higher the intensity of climate change awareness and response behavior. As this study aims to identify the factors determining the support for taxes to address climate change, it is assumed that a higher

and related policies, measured through self-reported familiarity with climate change issues and government policies. This construct differs from acceptance of climate risk, which reflects the perceived severity and vulnerability associated with climate threats. As demonstrated by van der Linden [19], knowledge and risk perception represent distinct psychological constructs that influence climate policy support through different pathways. Knowledge primarily operates through cogni- tive processes, while risk acceptance involves affective judgments of potential harm. In line with the previous studies, we believe that knowledge of climate change will have a significant effect on risk per- ception and the acceptance of the plastic tax. Thus, the following hypothesis is proposed. Hypothesis 6. The higher the knowledge of climate change, the higher acceptance of the plastic tax. Trust. Trust is a representative socio-cultural factor in risk research, and it plays an important role in improving individuals’ risk perception, safety, and risk response effectiveness [79]. In risk research studies, trust can be defined as the level of confidence individuals have in organizations that provide information about risks and directly or indirectly

PLOS One | https://doi.org/10.1371/journal.pone.0337327 December 29, 2025 8 / 30 manage them [80]. Many studies have analyzed trust in the context of risk object, that is, nuclear acceptance [44,79,81]. Positive trust reduces risk perception and increases acceptance, which emphasizes the need for trust management. Visschers et al. [72] found that trust in the utility and government in nuclear power operations influenced the acceptance of nuclear power before and after the Fukushima nuclear accident. In this study, we believe that trust in the government is particularly important in the context of climate change policy, and reasons for distrust include a lack of confidence in the government’s ability to manage nuclear energy, perceived unfairness, or a perception that the government does not share their values. In this study, trust in government“ construct specifically measures confidence in government capability and effective- ness to address climate change, rather than belief alignment. As Poortinga et al. [36] distinguish, this represents “compe- tence trust” rather than “value similarity trust.” Our items assess whether respondents believe the government’s climate goals are achievable and whether the government is effectively addressing climate change. Thus, the following hypothesis is proposed Hypothesis 7. Increased trust in government regarding climate change will increase acceptance of the plastic tax. Emotions. Emotions can be defined as good or bad feelings toward external stimuli. In particular, emotions are

highlighted in relation to nuclear energy, emphasizing the inability of rational and reasonable judgment to operate [82]. Emotions are expressed as feelings, sentiments, and stigmas, and in nuclear research, they can be understood as the negative images that people have of nuclear power plants and nuclear containment centers [83]. Huijts et al. [84] confirmed that emotions were determinants of the attitude toward energy. Visschers et al. [72] confirmed that positive feelings in the affective dimension positively affected the acceptance of nuclear energy by lowering risk perception and increasing benefit perception. Kim et al. [74] confirmed that negative emotions had a significant impact on nuclear energy acceptance. Lim et al. [85] found that emotions had a negative impact on the perception of nuclear energy. In this study, we believe that negative emotions related to climate change will positively affect the support for and support future greenhouse gas reduction policies. Thus, the following hypothesis is proposed: Hypothesis 8. The higher the negative emotions related to climate change, the higher acceptance of the plastic tax. Planned behavior factors Climate change skepticism. Skeptical environmentalism, also known as environmental skepticism, refers to the belief that the environmental crisis claimed by scientists and environmental scientists is overestimated and that there are data errors [74]. Climate change skepticism is conceptually related to awareness of consequences (AC) from the VBN

theory. As demonstrated by Poortinga et al. [36], climate skepticism fundamentally undermines the acknowledgment of consequences, serving as an inverse indicator of AC. Those with higher skepticism typically demonstrate lower awareness of environmental consequences. Lomborg [86] found that skeptics with strong anti-environmentalist leanings believed that environmentalism was a threat to social and economic progress and civil liberties. Whitmarsh [87] found that skepticism was a structural problem, with the proportion of people believing in climate change being overestimated to more than double the value between 2003 and 2008. Climate change skepticism is a position that denies the seriousness of climate change, and is sometimes referred to as climate change denialism [73]. Albayrak et al. [88] analyzed the causal relationship between skepticism and environmental behavior and found that the weaker the skepticism, the stronger the pro-environmental purchasing behavior. Further, the stronger the skepticism, the lower the climate change awareness and intention to act [73]. Thus, the following hypothesis is proposed: Hypothesis 9. Climate change skepticism moderates the relationship between climate change values, risk perception paradigm, and acceptance of the plastic tax.

PLOS One | https://doi.org/10.1371/journal.pone.0337327 December 29, 2025 9 / 30 Guilt toward climate change. Guilt is a response to personal responsibility for wrongdoing when some social standard has been violated [89]. Individuals who feel guilty want to undo their actions; guilt typically elicits a pro-social response, characterized by repairing the harm caused by their wrongdoing. Moreover, eco-guilt refers to a negative emotional state that occurs when people perceive that they have failed to meet personal or social standards for environment-friendly behavior. Guilt can often act as a motivating factor to make significant changes in behavior to become more eco-friendly. Ferguson et al. [90] demonstrated that climate change-related behavior was facilitated when groups, including individuals, perceived responsibility for climate change and felt guilty about it. Wang [91] explored the determinants of climate change behavioral intention and found that self-efficacy, guilt, attitude, and consideration of future consequences predicted behavioral intention to mitigate global warming. In this study, we examine the role of climate change guilt in moderating the relationship between value and risk perception factors and the acceptance of the plastic tax. Thus, the following hypothesis is proposed: Hypothesis 10. Guilt moderates the relationship between climate change values and risk perception paradigms and acceptance of the plastic tax. Self-efficacy. Self-efficacy is belief in one’s abilities [92] and refers to the satisfaction felt by an individual regarding their

role and actions related to their environment [65]. It is belief in one’s ability to organize and sustain the activities necessary to achieve a specific goal. Self-efficacy is associated with cognitive functioning through its impact on self-satisfaction with personal development and the demands of selected goals, and is one of the best predictors of environmental behavior [93]. Lee et al. [94] found that self-efficacy had a significant positive effect on eco-friendly behavior. Kim et al. [65] also confirmed that self-efficacy had a positive influence on environmentalism. Tabernero et al. [95] found that self-efficacy triggered the intrinsic motivation to practice self-regulatory environmental behaviors such as recycling. Therefore, this study aims to investigate the effect of self-efficacy in climate change on the determinants of the support for the plastic tax. Hypothesis 11. Self-efficacy moderates the relationship between climate change values, risk perception paradigm, and acceptance of the plastic tax. Planned behavior factor as a moderator. In this study, we assumed that the three variables that comprise planned behavior play a moderating role in the relationship between value/risk perception and plastic tax. Logically, planned behavior is a powerful variable that can influence intentions and attitudes, as proven by prior studies [65,94,95]. Moreover, the moderating role of planned behavior factors such as attitude, norm, and efficacy has received increasing attention.

Yang et al. [96] showed that the effects of an interaction between attention to efficacy messages and that to threat messages on behavioral intention vary among people with different attitudes, subjective norms, and perceived behavioral control. Norms influence a variety of climate change-related behaviors. Wang [91] showed that moral attitudes, self- efficacy, anticipated guilt, and consideration of future consequences predicted one’s intentions to engage in behaviors to alleviate global warming. Moghavvemi [97] demonstrated that feelings of guilt about contributing to air pollution and an awareness of the advantages of using LED lights both activate individual personal norms and attitudes and influence the intention to buy LED lights. This study adopts climate change skepticism as the attitudinal variable that constitutes the planned behavior. According to Chen [98], the moderating effect of climate change skepticism on the positive relationship between pro-environmental self-identity and purchase intentions of sustainable labeled coffee was verified. Accordingly, the following hypothesis is proposed. Hypothesis 11. Skepticism, guilt, and efficacy moderates the relationship between climate change values, risk perception paradigm, and the willingness to pay the plastic tax. Based on motivated reasoning theory, climate change skepticism should weaken the positive relationships between pro-environmental values and plastic tax support, as skeptics discount environmental information [24]. Research demon-

strates that skepticism attenuates the value-behavior link by reducing perceived policy necessity [17].

PLOS One | https://doi.org/10.1371/journal.pone.0337327 December 29, 2025 10 / 30 For guilt moderation, moral self-regulation theory suggests that guilt amplifies value-behavior consistency by height- ening moral salience [99]. Studies show guilt strengthens the relationship between environmental concerns and policy support among high-guilt individuals [18]. Regarding efficacy, social cognitive theory indicates that self-efficacy enhances the translation of values into behavioral intentions when individuals believe their actions matter [30]. Research confirms efficacy moderates the environmental value-behavior relationship [100]. Based on those literatures, we propose specific hypotheses: H9a: Climate change skepticism negatively moderates the relationship between environmentalism and plastic tax support H10a: Guilt positively moderates the relationship between environmental values and plastic tax support H11a: Self-efficacy positively moderates the relationship between perceived risk and plastic tax support. Method section Data collection and ethical statement This study used nationally representative survey data for the analysis. A nationwide survey was conducted by a profes- sional polling agency from May 30 to June 3, 2022, with 1,571 adults aged 19 and above. Participants were recruited through a professional polling agency using stratified random sampling based on region, gender, and age demographics matching Korean population statistics. This study employed a nationally representative cross-sectional survey design

following established protocols [101]. A stratified random sample of 1,571 Korean adults (aged 19+) was recruited through a professional polling agency using proportional quota sampling by region, gender, and age. The web-based survey achieved a 95% confidence level with ±2.5% sampling error. The web-based survey was administered from May 30 to June 3, 2022. Survey links were distributed via text mes- sages and emails to eligible participants. The questionnaire employed block randomization to minimize order effects, with value measures, risk perception items, and planned behavior scales presented in randomized sequences across participants. Informed consent was obtained electronically before survey completion. The average completion time was approximately 15 minutes. This study was conducted in accordance with the Declaration of Helsinki principles and Korean ethical research standards. Ethical review exemption was granted under the Korean Bioethics and Safety Act (2005), Article 15 [2], which permits exemption for research meeting specific minimal risk criteria aligned with interna- tional standards. Our study qualified for exemption under multiple established categories. First, the research involved minimal risk to participants, defined as risk no greater than that encountered in daily life activities. Survey questions addressed standard psychological constructs (attitudes, values, perceptions) commonly used in social science research without sensitive top-

ics that could cause psychological distress. Second, our web-based methodology eliminated face-to-face contact, which under Korean regulations requires additional IRB oversight due to potential identification risks. The anonymous online platform ensured participant confidentiality throughout data collection, with no mechanism for linking responses to indi- vidual identities. Third, we collected no personally identifiable information as defined under Korean Personal Information Protection Act Article 23. Demographic variables (age, gender, education, income) were collected in categorical ranges without specific details that could enable individual identification. Despite exemption status, we implemented comprehensive participant protection protocols. Electronic informed con- sent was obtained from all participants before survey access, including clear information about study purpose, voluntary participation nature, estimated completion time, data usage intentions, and unconditional right to withdraw without penalty. Participants received explicit assurance that responses would remain anonymous and confidential, with data stored on secure servers using encryption protocols. No personal contact information was collected or retained, ensuring complete anonymity throughout the research process.

PLOS One | https://doi.org/10.1371/journal.pone.0337327 December 29, 2025 11 / 30 We conducted thorough risk assessment demonstrating minimal potential for harm. Survey questions addressed commonly studied psychological constructs without probing sensitive personal experiences, traumatic events, or stigma- tized behaviors. The environmental policy topic represents low-risk subject matter unlikely to cause emotional distress or social vulnerability. Data collection procedures minimized any residual risks through anonymous participation, voluntary response options for all questions, and clear withdrawal procedures accessible throughout survey completion. Our exemption approach aligns with international research ethics frameworks, including U.S. Federal Policy for Protec- tion of Human Subjects (45 CFR 46) categories for exempt research involving anonymous surveys on non- sensitive topics. Similar exemption criteria exist in European and other international contexts for minimal risk social science research. The Korean Bioethics and Safety Act criteria mirror international standards by distinguishing between research requiring full IRB review and minimal risk social science surveys warranting exemption with appropriate safe- guards. Complete exemption documentation was maintained according to Korean regulatory requirements, including detailed protocol descriptions, risk assessments, and participant protection measures, with our research institution’s ethics office confirming exemption appropriateness under applicable regulations.

The demographic characteristics of the respondents were as follows: 772 (49.1%) male and 799 (50.9%) female, with 255 (16.2%) respondents being aged between 19 and 29, 233 (14.8%) aged between 30 and 39, 294 (18.7%) aged between 40 and 49, 314 (20.0%) aged between 50 and 59, and 475 (30.2%) aged 60 and above. In terms of education, 792 (50.1%) had a high school diploma or less, and 779 (49.6%) had a college degree or higher. In terms of income, 1066 (67.9%) earned less than 6 million won, and 505 (32.1%) earned more than 6 million won. Measures and reliability The measurement items and reliability analysis are shown in Table 1, and the reliability test showed that the Cronbach’s α coefficient ranged from 0.635 to 0.891, confirming that the reliability values were all met. All of the questions were measured using a 5-point Likert scale except altruism, and the mean value was used as a variable. Our scale items were carefully selected from established literature with strong psychometric properties. For climate change skepticism, we adopted items from Whitmarsh [87], who developed and validated a comprehensive skepticism scale. This approach aligns with McCright et al’s [102] work in Global Environmental Change measuring public climate skepticism. Our guilt measurement follows Ferguson et al. [90] in Journal of Environmental Psychology, who demon- strated how collective guilt mediates climate change beliefs and mitigation behaviors. Harth et al. [89] similarly validated

guilt measures predicting distinct environmental intentions. For efficacy, we utilized measurements from Bandura’s [93] framework, following Lauren et al.’s [100] application in Journal of Environmental Psychology showing self-efficacy’s importance in environmental behavior. All analyses were conducted using SPSS version 28.0. Descriptive statistics, correlation analyses, and hierarchical multiple regression were performed following established protocols. Moderation analyses employed the PROCESS macro v4.0 [103] with bootstrap confidence intervals (n = 5000). Missing data were handled using listwise deletion (<2% missing cases). Analysis and findings Descriptive analysis To evaluate how the respondents reacted to the plastic tax, we conducted a frequency analysis of the statement, “I sup- port the idea of taxing plastic users more to reduce plastic use.” Fig 1 illustrates the results. With 51.3% in favor of the idea and 13% against it, the plastic tax is found to have a strong positive sentiment among respondents. However, 35.8% of the respondents remained neutral, indicating the potential for attitudinal change.

PLOS One | https://doi.org/10.1371/journal.pone.0337327 December 29, 2025 12 / 30 The second statement about the plastic tax (“I am in favor of taxing plastic users as long as the taxes are reinvested in environmental improvements to reduce plastic use”) was analyzed under the condition that the revenue would be used for environmental purposes. Overall, 54.9% of the respondents were in favor, while 12.1% were opposed. Compared with Fig 1, the percent- age of favorable responses increased by 3.6%, neutral responses decreased by 2.7%, and opposing responses slightly decreased by 0.9%. Although these differences are relatively small, the consistently high proportion of neutral responses(33.1%) suggests a lack of strong consensus regarding the plastic tax, even when its environmental benefits are emphasized (Fig 2). To analyze the differences in plastic tax preferences according to demographic variables, we conducted a mean analysis. Fig 3 shows the results of the analysis. The average of the scores for the two questions measuring plastic tax was estimated. First, the sex-based difference showed that women had more positive attitude toward the plastic tax than men, reflecting women’s greater sensitivity to environmental issues [104,105]. However, this difference between groups is not Table 1. Measurement questions and reliability analysis results. Measurement Concepts Statements Cronbach α scale Willingness to pay plastic tax I favor the idea of taxing plastic users more to reduce plastic use. .635 5

I am in favor of taxing plastic users to reduce plastic use, provided that the taxes are reinvested in environmental improvements. Value Factors Environmentalism I think a lot about the damage we do to the environment. .761 5 I often worry about the effects of pollution on me and my family. Altruism Peaceful world: life without war and conflict .837 7 Social justice: correcting injustice, helping the weak Helping: working for the well-being of others Egalitarianism We need systemic reforms to share wealth equitably.. .761 5 Many of our problems would be solved if our society were more equal. Economic materialism Economic development should be prioritized over conservation. .820 5 Economic development should come first, followed by environmental protection. Risk Perception Paradigm Perceived risk Climate change is a very serious problem that cannot be compared to any other risk. .798 5 The changes caused by climate change will cause a lot of damage to me and my family. Knowledge I am familiar with government policies to address climate change. .744 5 I am more knowledgeable than others about climate change issues. Government trust The government’s goals to address climate change will be successful.. .794 5 The government’s goals to address climate change are achievable. I believe the government is doing a good job in addressing climate change. Emotions I have negative thoughts about climate change. .726 5 The picture of our future under climate change is very dark. Environmental Psychology Climate change skepticism

The problem of climate change has been exaggerated. .891 5 The damage caused by climate change is exaggerated. Guilt I regret not doing more to prevent climate change. .756 5 I feel guilty for not taking action to address climate change.. Efficacy Climate change is solvable depending on what I do. .840 5 I can solve the climate change problem if I try. https://doi.org/10.1371/journal.pone.0337327.t001

PLOS One | https://doi.org/10.1371/journal.pone.0337327 December 29, 2025 13 / 30 significant (t = 2.134, p = 1.44). In terms of age, a positive attitude toward the plastic tax was higher among those aged 40 and older than those in their 20s and 30s, and the level of favorability increases with increasing age from 40 to 60 (f = 19.616, p = .000). This may reflect the fact that older people are more likely to have experienced the damaging effects of plastic. This may also be due to their financial ability to pay the plastic tax. Regarding education level, respondents with a high school diploma or higher were more likely to be in favor of the plastic tax than those with a high school diploma or less (t = 2.797, p = 0.095). This is the result of increased knowledge about plastic through education. Regarding income, the support for a tax is higher in the higher income group (f = 4.371, p = 0.013), probably due to the shared monetary nature of tax and income. A bivariate correlation analysis was conducted between risk perception, value, and environmental psychological factors regarding the acceptance of the plastic tax (Table 2). Pearson’s correlation coefficient has a value range from −1–1. As there is no absolute criterion to indicate whether the correlation between variables is large or small, this study considered the absolute value of 0.5 or more to represent a high correlation between variables. The results showed that perceived risk and emotion had correlation coefficients of 0.5 or higher (r = .571, p < .001).