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How can carbon labels and climate-friendly default options on restaurant menus contribute to the reduction of greenhouse gas emissions associated with dining?

['Ann-Katrin Betz', 'Department Of Psychology', 'Julius-Maximilians-Universität Würzburg', 'Würzburg', 'Benedikt T. Seger', 'Gerhild Nieding']

Date: 2022-05

In this study, we aimed to understand how restaurants can contribute to climate change mitigation via menu design. We investigated two types of interventions: changing the configuration of menu entries with variable side dishes so that the most climate-friendly option is set as the default and indicating the greenhouse gas emission of each dish via carbon labels. In an online simulation experiment, 265 participants were shown the menus of nine different restaurants and had to choose exactly one dish per menu. In six menus, the main dishes were presented with different default options: the side dish was associated either with the highest or with the lowest greenhouse gas emissions. The other three menus consisted of unitary dishes for which the default rules did not apply. All menus were presented either with or without carbon labels for each dish option. The results indicated that more climate-friendly dish choices resulting in lower greenhouse gas emissions were made with the low-emission than the high-emission default condition, and when carbon labels were present rather than absent. The effects of both interventions interacted, which indicates that the interventions partly overlap with regard to cognitive predecessors of choice behavior, such as attentional focus and social norms. The results suggest that the design of restaurant menus has a considerable effect on the carbon footprint of dining.

Introduction

In our study, we investigated how restaurant menus can be designed to help guests choose more climate-friendly meals. There are three main reasons for believing that this research direction may be worthwhile. First, humans–especially those living in industrialized societies–need to reduce their greenhouse gas (GHG) emissions substantially to mitigate global warming [1,2]. The impact of agriculture and nutrition on GHG emissions, and their potential to contribute to more sustainable societies, is significant [3,4]. Second, although individual consumption as an isolated factor has only limited influence on GHG emissions at the societal level [5,6], individuals can significantly reduce their carbon footprint by changing their nutrition behavior. In industrialized countries, nutrition accounts for approximately 15% of an individual’s total GHG emissions [5,7], and there are considerable differences between food types in terms of GHG emission levels measured in kilograms of carbon dioxide equivalents per kilogram (kg CO 2 e). For example, vegetables such as zucchinis (0.25 kg CO 2 e) yield approximately 50 times less GHG emissions than beef (12.29 kg CO 2 e; [8]). Third, in industrialized societies, restaurants and similar settings, such as cafeterias and canteens, are often frequented. For example, a large-scale survey in Germany in 2018 revealed that 20% of the participants dined out at least once every week [9]. However, past research on pro-environmental behavior has mainly focused on purchasing food and eating at home [10–12]. At the same time, customers are showing growing interest in restaurants that participate in more ecologically sustainable practices [13].

As a part of ecologically sustainable practices, restaurants can help diners reduce their carbon footprint via dish choices. To this end, changing menu design may result in considerable positive effects. On the one hand, adding information about the ecological impact of the dishes is feasible and both customers and restaurants have expressed an interest in such information [14,15]. Carbon labels that provide information about products’ GHG emissions have the potential to reduce the carbon footprint of consumer choices [16,17]. Analogously, the field of health promotion has provided meta-analytic evidence that health-related labels move people toward healthier food choices [18]. On the other hand, dishes that feature variable components (e.g., a burger with a beef or vegetable patty) usually have one of these components set as the default option. Evidence from several investigations on environmentally friendly behavior suggests that defaults are more likely to be chosen than the other options [12,19,20]. Therefore, the climate impact of chosen dishes with variable components may be significantly reduced by using components with the lowest GHG emissions as the default option.

Both types of intervention can be classified as behaviorally informed strategies, commonly known as “nudges” [10]. Nudging [21,22] is defined as a minimal change to the decision-making context with the intention of directing people’s behavior toward a desirable outcome for themselves and others without limiting their real or perceived freedom of action. These interventions exclude mandates and bans as well as economic incentives and disincentives. According to a recent review of behaviorally informed interventions aimed at climate-friendly food consumption [10], carbon labels can be classified as disclosures when they provide ecological information about a food item (e.g., GHG emissions) and as warnings when the label features salient information connoted with emotional value (e.g., traffic-light colors). There are several studies in the context of health- [18,23–25] and environment-related food choice [16,17,23–27] in which the examined labels combined these two types of nudging. In other studies, default and non-default dishes were varied systematically on menus or board menus [28–31]. To the best of our knowledge, no published study has yet examined the combined effects of defaults and carbon labels on food choice, although both types of interventions have yielded promising results in earlier studies and can easily be implemented together. Therefore, the goal of our study was to investigate how the carbon footprint of dish choices can be reduced by using climate-friendly components as default options and by providing information about the GHG emissions for each dish.

Menu defaults In the past decade, there have been several attempts to reduce the ecological footprint of dish choices in restaurants and similar settings by changing menu design. In a study conducted online that used a hypothetical restaurant setting, participants chose vegetarian meals more often when they appeared at the top of the menu than in a separate vegetarian section at the bottom [32]. Another online study revealed that approximately three of four participants make vegetarian choices when the menu includes only vegetarian dishes with extra-meat options listed at the bottom of the menu. By contrast, only about half of the participants choose vegetarian dishes when the menu lists vegetarian and meat dishes together [31]. Field studies in campus cafeterias produced similar results: when vegetarian dishes are placed at the top of the board menu, the share of sold vegetarian dishes increases [28,33]. However, none of these studies have directly examined dishes with variable components and it can be argued that a variable component that appears at the most accessible position of the menu (e.g., top or left)–thus constituting the default option–may benefit from similar positive effects. How are the effects of default-related interventions in restaurant menus related to processes of climate-friendly behavior changes? To begin with, sticking to defaults may result from psychological inertia [34]. Accordingly, people who are indifferent about their dish choices would most likely choose the dish that is most readily available. A similar explanation has to do with the behavioral effort involved in opting against the default [35]. In this case, switching the default component from a beef to a vegetable patty in a burger menu can reduce the carbon footprint of customers who usually order “just a burger,” without having the customers change their actual behavior. Although this view on defaults may sound appealing to practitioners, this may not be the case with restaurant settings: the inertia-based explanation is tailored to situations in which the status quo can be maintained [34], meaning that one does not have to make a choice. By contrast, guests at a restaurant are usually forced to choose one of the offered dishes. It is also not very likely that diners are indifferent about what they are going to order. Alternatively, defaults may be more attention-grabbing or salient than other options [28,36]. In menus with a salient dish option (e.g., the one placed at the top, typed in a bigger font, or with a picture of the dish), a customer’s attentional focus is directed to this option more than to the others so that it receives overproportionate weighing in subsequent decision-making [37]. However, this does not necessarily imply that a more salient option is chosen more often. Rather, it depends on which features of the option are made salient, such as price or healthiness. When such features are framed negatively (e.g., when the food item is marked as particularly unhealthy), making them salient can reduce the probability of the option being chosen [38]. We will come back to this topic when addressing carbon labels. Finally, defaults can be considered implicit recommendations [39,40], thus constituting a kind of social influence. De Vaan et al. [31] found that menu design impacts perceived social norms: a menu with vegetarian defaults suggests that the majority of the guests order a vegetarian dish (descriptive norm) and that the majority of the guests would disapprove of ordering a meat dish (injunctive norm; [41]). The notion that defaults are implicit recommendations is also consistent with Bacon and Krpan’s finding that an additional explicit recommendation (i.e., declaring the top dish as “the chef’s recommendation”) does not further increase the frequency the dish being chosen [32].

Carbon labels Labels that indicate food items’ GHG emissions have been examined in dining [23,26,27,42,43] and grocery shopping [16,17,24,25,44] settings. In most cases, such labels combine explicit information (disclosure) with a color signal (warning; [10]). Results from a field study in a university cafeteria [26] indicate that carbon labels have a rather small effect on the sales of climate-friendly dishes. Specifically, the labels induced a considerable shift from higher- to lower-emission dishes for meat and fish categories, but not for vegetarian categories, nor was there a significant shift in sales between categories (i.e., the share of sold vegetarian dishes did not increase in total). In laboratory and online studies with fictive dining settings, the findings have been more heterogeneous: Osman and Thornton’s [23] results suggest that labels positively affect more climate-friendly dish choices, whereas the results of Babakhani et al. [43] do not. In the context of grocery shopping, the majority of studies have shown that carbon labels [16,17,25,44] have a positive effect, which can explain the consumers’ choice behavior beyond a product’s price [16,44]. However, a recent online experiment has found that carbon and nutrition labels introduced simultaneously had no effect on the climate impact of food choices [24]. Again, different processes related to consumer behavior changes can be assumed to exist behind carbon labels’ impact on food choice. Several studies addressed here [17,23,24,27,42] have emphasized labels’ informative content or, more generally, knowledge acquisition as a crucial predictor of climate-friendly food choices. In the literature on environmental behavior changes, three types of knowledge have been identified as relevant [45]: system knowledge, which refers to knowledge related to ecosystems and ecological problems (e.g., that human-made GHG emissions cause global warming); action-related knowledge, which is related to the behavioral options that people have in order to resolve ecological problems (e.g., reducing meat consumption lowers individual GHG emissions); and effectiveness knowledge, which comprises information on the relative benefits or harm of different behavioral options (e.g., replacing a beef patty with a vegetable patty in a burger reduces GHG emissions more than replacing the beef patty with a cheese-spinach patty). Generally, action-related knowledge requires system knowledge, effectiveness knowledge requires action-related knowledge, and all three types of knowledge are necessary for effective pro-environmental behavior. In line with this reasoning, evidence on carbon labels suggests that such labels only work when customers are familiar with the ecological background of the labels (i.e., have enough system knowledge) and that carbon labels have the potential to encourage climate-friendly dish choices by improving action-related and effectiveness knowledge. Regarding system knowledge, the results obtained by Spaargaren et al. indicate that carbon labels are only effective when embedded in a comprehensive informational strategy [27]. A qualitative study suggests that people need to be informed about the concepts of the carbon footprint and carbon labels [42]. With reference to action-related knowledge, Osman and Thornton [23] have suggested that more accurate information (i.e., labels indicating “CO 2 emissions” and not just “environmental impact”) increases the benefits of labels. In line with the idea of effectiveness knowledge, the authors of a shopping study in which the carbon footprint of each product was expressed numerically [17] have argued that such quantified information enables customers to have a realistic idea of food-related GHG emissions, which people tend to underestimate. Carbon labels also improve the accuracy of ranking food items according to their climate impact, even when the labels do not include quantified information and when participants are under time pressure [25]. In food labels, ecological or health information is often combined with a color stimulus, which, in cases of high GHG emissions (or other detrimental effects, such as unhealthiness), should act as a warning signal [10]. To achieve that customers give GHG emissions enough weight when making their dish choices, labels have to be salient [36–38]. In Spaargaren et al.’s field study [27], carbon labels were effective only when they were color-coded; however, an information campaign was introduced at the same time, so it remains unclear to what extent the nascent effect was caused by the colored labels. In this regard, clearer results were obtained in an online coffee-choice experiment [16], whereby the impact of carbon labels was greater when they were designed using traffic-light colors than black-and-white. Two studies have attributed the failure to find an effect of carbon labels on food choice to a lack of salience. De Bauw et al. [24] argued that carbon labels were not effective in their online grocery setting because the labels appeared below the nutrition labels (which were effective) and were thus less salient. In Babakhani et al.’s eye-tracking experiment [43], participants spent only 2–3 seconds (3% of total dwelling time) on a colored carbon label when studying a page describing a burger dish. The participants also did not look first at the label, which indicates that traffic-light carbon labels are not salient enough so that customers pay special attention to them. However, the lack of salience may have to do with the fact that a picture of the dish was included on each page, which may have been more salient than a rather small label. In sum, there is evidence that salience is an important criterion for the effectiveness of carbon labels, but further research is needed.

Combination of defaults and labels To our knowledge, the combination of default variations and labels has not yet been studied in the context of dining. However, a similar study [46] combined two types of default in a restaurant setting: one designating an option as “standard,” and one pre-selected option that required diners to deliberately opt out when not choosing the default dish. The results indicated that the effectiveness of the standard default diminished considerably when one option was pre-selected. Other studies have examined the effects of two types of food label. In one case, the effects of organic and animal welfare labels on egg purchases were not additive when combined [47]. Another food shopping experiment [48] demonstrated a similar interaction effect between organic and local origin labeling among European consumers. this less-than-additive effect of two nudging strategies can be accounted for by the basic economic principle of decreasing marginal utility, which suggests that an increasing number of behavioral interventions serving the same goal reduces the effectiveness of each behavioral intervention in relation to that goal [47,48]. From a psychological perspective, there is theoretical [49] and empirical [50] evidence that minimal changes to the configuration of a decision situation (e.g., switching the default), combined with a short information that elicits attentional resources toward certain aspects of the decision in question (e.g., carbon labels), should be an effective measure. The latter type of intervention is often referred to as prompting and is common in several fields that have to do with health- or environment-related behavior, such as nutrition [51], recycling [52], and energy saving [53,54]. Prompts are usually placed close to the location where the target behavior happens–for example, a banner at the entry of a supermarket [51] or a sticker on a power strip that reminds users to switch it off before leaving the office [54]. Prompts often include polite persuasive messages so that the recipient’s perceived freedom of choice is not reduced [53]. A meta-analysis of experiments that targeted pro-environmental behavior change [50] indicates that prompting and minimal changes to the decisional situation contribute substantially to behavior changes, especially when the two are applied in combination. Therefore, there is also reason to believe that the effects of low-emission defaults and carbon labels add up when applied in combination.

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[1] Url: https://journals.plos.org/climate/article?id=10.1371/journal.pclm.0000028

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