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

be attributed to the gender differences in pro-environmental attitudes that females are found to be more environmentally friendly than males [26]. For pro-environmental behaviors, how- ever, the effects of education attainment do not display gender differences. Second, given the huge urban-rural divide in China, it is interesting to study whether the education effects are different between these two areas. Columns (3) and (9) present the results for urban residents, while columns (4) and (10) present the results for rural residents. The coefficient on education is positive and significant for rural residents but insignificant for urban residents. There are two possible explanations. First, rural residents exhibit less pro- environmental attitudes and behaviors than those urbanites, as found in our benchmark analy- sis. Second, rural residents are less exposed to the discussion about environmental issues, e.g. less access to social media. As a result, education plays a bigger role for these individuals. Finally, we investigate whether the education effects on pro-environmental attitudes and behaviors vary with income levels. To explore this possible heterogeneity, we divide our sam- ple into two distinct income groups, namely the groups of respondents whose income is in the top quintile and bottom quintile of the income distribution. Then we re-run the regressions separately for these two income groups. The results are presented in columns (5)-(6) and (11)- (12) of Table 5. The estimate of schooling years is positive and significant for people in low-

income groups, but insignificant for those with high income. Prior studies show that people’s demand for public goods such as clean environment will increase with income [45]. Accord- ingly, high income people might already have a high level of environmental awareness, so that the effect of additional schooling years become negligible. Put it in another word, our finding suggests that income can substitute for the effect of education. 4.3. Robustness checks 4.3.1. Placebo test. The validity of our instrument relies on the assumption that the CSL influences pro-environmental attitudes and behaviors only through its impact on education rather than through other pathways. Put differently, our instrument should not be systemati- cally correlated with the omitted variables that also affect pro-environmental attitudes and Table 5. Heterogeneity analysis. Pro-environmental attitudes Pro-environmental behaviors Male Female Urban Rural High income Low income Male Female Urban Rural High income Low income (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) Education 0.024��� 0.004 0.003 0.035��� 0.011 0.023�� 0.002�� 0.015�� 0.006 0.023�� 0.013 0.012� (0.009) (0.005) (0.007) (0.011) (0.012) (0.011) (0.001) (0.006) (0.006) (0.009) (0.011) (0.007) Controls Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Observations 1,646 1,810 1,807 1,649 718 656 1,734 1,928 1,876 1,786 753 712 First-stage estimation CSL 2.831��� 3.148��� 2.658��� 3.040��� 2.076��� 3.620��� 2.831��� 3.468��� 2.828��� 3.349��� 2.346��� 3.812���

(0.499) (0.375) (0.330) (0.535) (0.622) (0.837) (0.469) (0.372) (0.342) (0.555) (0.593) (0.811) F-statistics 32.12 70.50 64.72 32.19 11.12 18.67 36.55 86.92 68.25 36.34 15.62 22.08 Note: The table reports the results of heterogeneity analysis. The sample is split into two subsamples according to whether the individual is male in columns (1)-(2) and in columns (7)-(8); whether the individual lives in urban areas in columns (3)-(4) and in columns (9)-(10); and whether the individual earns high income in columns (5)-(6) and in columns (11)-(12). All regressions use 2SLS models for estimation and have the same controls as in column (2) of Table 3 except that the variable used as the criteria for splitting the sample is not included. The coefficients on the control variables are suppressed for brevity. Robust standard errors are clustered at the cohort-city level and are reported in parentheses. ���, �� and � indicate 1%, 5% and 10% significance levels, respectively. https://doi.org/10.1371/journal.pone.0263383.t005 PLOS ONE Green returns to education PLOS ONE | https://doi.org/10.1371/journal.pone.0263383 February 3, 2022 13 / 20