Green returns to education: Does education affect pro-environmental attitudes and behaviors in China?

4.3.3. Restricted sample. Given that our sample covers a long span of birth cohorts, we check the robustness of our results by considering a sample with shorter birth cohort span. In particular, we restrict our sample to those born less than 16 years earlier than the first CSL- affected cohort. Columns (5) and (6) of Table 6 report the results in the restricted sample. It turns out that the effects of education remain significantly positive. 5. Mechanism analysis After establishing the casual link between education and pro-environmental attitudes and behaviors, it would be interesting to explore the mechanism that drives this strong relation- ship. In particular, we focus on one important channel, namely environmental knowledge. The willingness to alleviate environmental problem is a partial function of risk perception, which is reflected in environmental knowledge [5]. The acquisition of environmental knowl- edge makes individuals more informed about the situation of local and global environment, negative health effects of environmental problems, and public environmental policies. Indeed, previous literature has established that education facilitates a better understanding of complex environmental messages such as climate change [15,19,20]. In other words, the environmental knowledge may play a major role in forming people’s pro-environmental attitudes and behav- iors. Hence, we postulate that the environmental knowledge may be a channel underlying the relationship between education and pro-environmental attitudes and behaviors. We test this mechanism in the following.

Environmental knowledge refers to people’s knowledge of environmental protection and climate literacy [15]. In the CGSS 2010, the respondents are asked ten true or false questions covering fundamental environmentally-related concepts to evaluate their environmental liter- acy. These questions are expressed as they would be present in daily life and media publicity. The exact wording of questions is provided in Table 7. Table 7. Summary of environmental knowledge. % of respondents Correct Incorrect Do not know Automobile exhaust does not pose a threat to human health. True or False? 81.2 12.4 6.4 Abuse of fertilizers and pesticides damages the environment. True or False? 83.6 9.6 6.8 Use of phosphorus-containing washing powder does not cause water pollution. True or False? 62.1 12.9 25.0 Fluoride emissions from fluorinated refrigerators damages the ozone layer in the atmosphere. True or False? 51.7 9.7 38.6 Acid rain has nothing to do with burning coal. True or False? 44.3 10.8 44.8 Species depend on each other, and the disappearance of one species has a chain reaction. True or False? 52.4 5.8 41.7 In the domestic air quality reports, air of third-level quality is better than air of first-level quality. True or False? 26.2 11.0 62.7 A single species of forest is more susceptible to pests and diseases. True or False? 44.4 9.2 46.3 In the domestic water pollution reports, water of Ⅴ (5) quality is better than water of Ⅰ (1) quality. True or False? 16.4 7.9 75.7 The increase in carbon dioxide in the atmosphere is a contributor of global

warming. True or False? 53.2 4.9 41.9 Note: This table reports the proportion of respondents providing correct, incorrect, and ‘‘do not know” answers to each of the ten environmental knowledge questions. Percentages may not sum up to 100 due to rounding. https://doi.org/10.1371/journal.pone.0263383.t007 PLOS ONE Green returns to education PLOS ONE | https://doi.org/10.1371/journal.pone.0263383 February 3, 2022 15 / 20