4.1. Main Results
Equation (1) is estimated using pooled cross-section and time-series data on 27 European countries for the period from 1996 to 2011. Given the length of the period, the first step of the analysis is to test the stationarity of the data. To this aim, the Im-Pesaran–Shin (IPS) (
Im et al. 2003) test has been applied. The test allows for individual effects, time trends and common time effects, based on the mean of the individual Dickey–Fuller t-statistics of each unit in the panel. The null hypothesis is that all the panels contain a unit root (I(1) behaviour), and the alternative hypothesis is that all the panels are stationary (I(0) behaviour). Since the IPS test result shows that the null of unit root can be rejected at the one percent significance level, we conclude that the series are stationary. Therefore, Equation (1) is estimated using the natural logarithm form.
In estimating panel data, the effect of country-specific characteristics, potentially correlated with the dependent variable, can be explored by estimating both the fixed and random effects models (
Cameron and Trivedi 2009). If country-specific characteristics are not correlated with the explanatory variables, the fixed effects should be preferred to random effects. Otherwise, the estimation of random effects is consistent and efficient. In order to choose between random and fixed effects we ran the Hausman test both for G1 and G2 group of European countries. For the G1 group of countries the statistic is equal to 69.75 (with a
p-value of 0.000), for the latter the statistic is 0.20 (with a
p-value of 0.999), whilst for the whole sample it is 59.90 (with a
p-value of 0.000). Therefore, we proceeded in our analysis by applying the fixed effects model for the G1 group and for the whole sample, and the random effects model for the G2 group.
The results for the G1-group are presented in Panel A of
Table 4, while the results for the G2-group are presented in Panel B of the same table. Columns 2–5 display the results when environmental tax revenue as a percentage of the GDP (ETRev_GDP) is taken as a dependent variable. Columns six and seven display the results when the total environmental tax revenue as a percentage of total tax revenue is used (ETRev_TAX), whilst the last two columns report the results when the total environmental tax revenue (ETRev_TOT) is considered.
In the upper part of
Table 4 we observe the estimation results for our main explicative variables, i.e., the institutional context, ICT and other imports for G1 countries. The obtained results support our hypotheses. In particular, the coefficient of the rule of law that enforces the process of tax collection and monitoring, as expected, is positive and significant. This confirms the evidence on the importance of the institutional strength for environmental tax collection. The magnitude of this coefficient is around 1.0 for the first and the third model specification, while it is higher for the second specification (around 1.3). This means that as the rule of law increases by 1% the environmental revenues increase more than 1.1%.
A significant and positive relationship between ICT and environmental taxation revenue as percentage of GDP (first model specification) and total environmental revenue (third model specification) is also confirmed, although the elasticity parameters are rather low (around 0.06). As argued, high levels of income in G1 countries permit an intensive substitution of “obsolete” ICT goods with new upgraded ones. The excessive consumption, substitution and disposal of these goods in the home market imply the payment of taxes, which increases the volume of ET revenue. This result is not confirmed in the case when environmental taxation revenue is expressed as a percentage of total taxation (second model specification). This could be due to the fact that environmental revenues from e-waste are still a small part of total taxation revenue.
The incidence of total imports except ICT goods on ET revenue is negative and significant in all the estimations of the G1 group. For these economies, greater importation of manufacturing goods reflects a shrinking production sector at home, and, as a consequence, a lower environmental tax burden. In fact, according to our estimation, an increase of one percent of importation of goods decreases environmental taxation revenue by 0.16% in the estimation with ETRev_GDP as dependent variable and 0.25% and 0.13% in the estimation with ETRev_TAX and ETRev_TOT variables, respectively. These results confirm the evidence on the transferring abroad of the production process of EU Western countries and, as a consequence, a decrease in pollution.
As far as other control variables are concerned, we observe that the environmental policy expressed through government expenditure influences ET revenue negatively. This confirms that the expenditure to improve environmental quality contributes to the decrease of the environmental tax revenues. These results hold in all our estimations with a coefficient that is around 0.1. When environmental public expenditure increases by 10% the revenues decrease by one percent.
As highlighted in the econometric model paragraph, environmental degradation is considered by two different indicators (i.e., by per capita generation of greenhouse gases and by greenhouse gases per surface area). In both cases, as expected, the impact of environmental degradation on environmental taxation revenue is positive and is around 0.4 in all the three specifications. This means that when pollution increases by one percent the environmental taxation revenue increases by 0.4%, which is evidence of the functionality of the environmental tax reform that European countries have started during the last two decades.
To reflect the effects of production and consumption, energy intensity of the economy is also included in our model. Unexpectedly, for this variable we do not find any relationship with ET revenue. What we do observe is that the use of energy from alternative sources such as water, solar, wind, wave and nuclear energy has a positive and significant relationship with ET revenue in the first and the third model, although the impact is rather small (0.08).
Finally, in order to consider the role played by the size of the economy as the fiscal base for environmental taxation, in the second and third specifications of the model we take into account the impact of GDP. However, for the first model it was not possible to consider this variable given that the environmental taxation revenue is already expressed in terms of income. For this reason, in this model we have introduced GDP per capita as a control variable (columns four and five), which is significant at the 10% level only when also GGEsa is accounted for. However, in the second and third specifications of the model the total GDP is highly significant with a coefficient that is equal to 0.4 in the former and 0.9 in the latter case.
Panel B of
Table 4 displays the estimated results for the EU Eastern countries. As expected, most of the above findings do not hold for this group of countries. In fact, none of our main determinants is found to have any impact on environmental taxation revenue. This result is due to many reasons. Firstly, this is probably because these countries are still characterised by a weak institutional context. As argued in the recent literature, the weakness of the institutions in these economies has a negative impact on the efficiency of environmental policies and on the quality of the environment. Secondly, the absence of the relationship between the imports and ET can be explained with the lower propensity of these economies to transfer the production processes abroad. As known, this can be the result of the FDI inflow (
Gorbunova et al. 2012) and cheaper labour that these countries register with respect to the EU Western countries. In these countries, domestic production is still a significant factor, constituting a base for the environmental taxation entries. In fact, the size of the GDP positively influences the collection of environmental tax revenues when ETRev_TOT is considered as the dependent variable. Finally, lower levels of income of EU Eastern countries lead to lower importation and longer utilisation of existing technologies. For these reasons, they do not create as much specific technological waste and, therefore, green taxes, as do the EU Western countries.
However, the G2-group of countries presents a high level of significance with respect to two important variables related to environment policies. In fact, environmental policy expressed through government expenditure (Pub_exp) influences ET revenue negatively, which is expected given that the aim of this kind of expenditure is to improve environmental quality. This relation is homogeneous in the two groups of countries.
Interestingly, the use of energy from alternative sources (Altern_En) also influences ET revenue positively in both groups of countries. This can be explained by the subsidising of green technologies. In fact, the installation of green sources of energy is often subsidised by governments through the entries collected from environmental taxation (
EEA 2005). It means that greater use of alternative energy sources is fuelled by increasing environmental taxes, which is confirmed by our findings that show very similar magnitude and significance of the parameters between the two groups. On the other hand, for the EU Eastern countries, a factor like GDP per capita has no influence on environmental taxation revenues, while the size of GDP significantly influences the collection of taxes only in the third model specification when the total amount of environmental taxation is taken as the dependent variable.
4.2. Robustness Tests
In order to check for the reliability of our results, we conducted a series of robustness tests. Firstly, we considered another variable reflecting the strength of institutional context such as the government effectiveness (Govern) indicator that is closely related to the rule of law (RoL). According to
Kaufmann et al. (
2010), this indicator reflects perceptions of the quality of public services, the quality of the civil service and the degree of its independence from political pressures, the quality of policy formulation and implementation, and the credibility of the government’s commitment to such policies, including environmental policies. Replacing the RoL variable with Govern we test whether the obtained results are influenced by the variable chosen. The findings are presented in
Table A2 in the
Appendix A. The estimated results do not seem to be sensitive to the use of a different explanatory institutional variable, in fact they are highly consistent with previous ones: (a) the Govern variable is found to hold a positive and significant relationship with environmental taxation revenue in the G1-group, but does not have a significant relationship with environmental taxation revenue in G2-group; (b) for the other control variables we observe that the signs and the level of significance are the same as in the previous estimations; (c) in the case of G2-group, the relationship with the environmental taxation revenue is found only for the Pub_exp and Altern_En variables, confirming that these countries have progressively and positively responded to the European Union laws and directives to combat pollution.
Secondly, since the number of European countries involved in each of the two groups is relatively small and some of the variables of interest do not have statistically significant impact on environmental tax revenues, in particular for G2 countries, we make an attempt to estimate the three model specifications on the whole sample.
Table A2 in the
Appendix A reports the estimated results. Our findings confirm the heterogeneity found in the two groups of countries. With respect to the results displayed in
Table 4, despite the significance of most of the variables, we can observe that the magnitude of the determinants of environmental taxation revenue becomes less strong if compared with EU Western countries and stronger when compared with EU Eastern countries.
The estimations do not seem to be sensitive to the use of the whole sample of countries when they are compared with the G1 sample group estimations, although the magnitudes of the estimated parameters are smaller in the whole sample with respect to the G1-group. However, they seem to be very different when compared with the G2 sample estimations, confirming that the two groups of countries have different environmental tax revenues determinants.