Consumption-based indicators such as the energy and carbon footprint of households are largely determined by their spending levels. An inequality of household expenditures in a population therefore implies an inequality of their environmental footprints. Figures 1a-c show European households by decile of expenditure and their associated footprints for energy and carbon in 2015. The figures show that increasing expenditure generally translated into larger footprints, but that the inequality decreased from expenditure to energy to carbon emissions with 10:10 ratios (the top decile divided by the bottom decile) of `r exp_10_10`, `r energy_10_10` and `r co2eq_10_10`, respectively. Total expenditure ranged from `r exp_bottom_decile` trn€ to `r exp_top_decile` trn€ (or `r fd_pae_bottom_decile`€ to `r fd_pae_top_decile`€ per adult equivalent) across bottom and top decile, the energy footprint from `r energy_bottom_decile` EJ to `r energy_top_decile` EJ (or `r energy_pae_bottom_decile` GJ/ae to `r energy_pae_top_decile` GJ/ae), and the carbon footprint from `r co2eq_bottom_decile` MtCO2eq to `r co2eq_top_decile` MtCO2eq (or `r co2eq_pae_bottom_decile` tCO2eq/ae to `r co2eq_pae_top_decile` tCO2eq/ae). The reason for this is evident from figures 1d-f. Both the energy intensity measured as energy use per € expenditure (d) and the carbon intensity measured as carbon per unit of energy use (f) gradually decrease from bottom to top expenditure decile. The average energy intensity of consumption decreased from `r mean_energy_intens_bottom_decile` MJ/€ in the bottom decile to less than half (`r mean_energy_intens_top_decile` MJ/€) in the top decile. Additionally, the carbon intensity of energy use was also higher in the bottom decile (`r mean_co2eq_of_energy_intens_bottom_decile` gCO2eq/TJ) compared to the top decile (`r mean_co2eq_of_energy_intens_top_decile` gCO2eq/TJ). There is a clear trend of decreasing intensities across expenditure deciles even though the variance in the lower deciles is much higher. The carbon intensity of consumption (figure 1e) combines the effects of the intensities of 1d and 1f. The higher carbon intensity of energy use is likely due to a larger share of emission intensive energy carriers in the energy system. The decreasing energy intensity per expenditure is due to either inefficient energy technologies or energy subsidies in poorer areas in Europe.
Consumption-based indicators such as the energy and carbon footprint of households are largely determined by their spending levels. An inequality of household expenditures in a population therefore implies an inequality of their environmental footprints. Figures 1a-c show European households by decile of expenditure and their associated footprints for energy and carbon in 2015. The figures show that increasing expenditure generally translated into larger footprints, but that the inequality decreased from expenditure to energy to carbon, with 10:10 ratios (the top decile divided by the bottom decile) of `r exp_10_10`, `r energy_10_10` and `r co2eq_10_10`, respectively. Total expenditure ranged from `r exp_bottom_decile` trn€ to `r exp_top_decile` trn€ (or `r fd_pae_bottom_decile`€ to `r fd_pae_top_decile`€ per adult equivalent) across bottom and top decile, the energy footprint from `r energy_bottom_decile` EJ to `r energy_top_decile` EJ (or `r energy_pae_bottom_decile` GJ/ae to `r energy_pae_top_decile` GJ/ae), and the carbon footprint from `r co2eq_bottom_decile` MtCO2eq to `r co2eq_top_decile` MtCO2eq (or `r co2eq_pae_bottom_decile` tCO2eq/ae to `r co2eq_pae_top_decile` tCO2eq/ae). The reason for this is evident from figures 1d-f. Both the energy intensity of consumption, measured as energy use per € expenditure (d), and the carbon intensity of energy, measured as carbon per unit of energy use (f), gradually decrease from bottom to top expenditure decile. The weighted average energy intensity of consumption decreased from `r mean_energy_intens_bottom_decile` MJ/€ in the bottom decile to less than half (`r mean_energy_intens_top_decile` MJ/€) in the top decile. Additionally, the carbon intensity of energy was also higher in the bottom decile (`r mean_co2eq_of_energy_intens_bottom_decile` gCO2eq/TJ) compared to the top decile (`r mean_co2eq_of_energy_intens_top_decile` gCO2eq/TJ). There is a clear trend of decreasing intensities across expenditure deciles even though the variance in the lower deciles is much higher. The carbon intensity of consumption (figure 1e) combines the effects of the intensities of 1d and 1f. The higher carbon intensity of energy is likely due to a larger share of emission intensive energy carriers in the energy system. The decreasing energy intensity of consumption is due to either inefficient energy technologies or energy subsidies in lower-income areas in Europe.
```{r figure1, out.width="98%", fig.cap="Expenditure and environmental footprints and intensities across European expenditure deciles. Total expenditures (a), energy footprint (b), and carbon footprint (c) per decile. Energy intensity as energy footprint per expenditure (d), carbon intensity as carbon footprint per expenditure (e), and carbon intensity as carbon footprint per energy footprint (f)."}
```{r figure1, out.width="98%", fig.cap="Expenditure and environmental footprints and intensities across European expenditure deciles. Total expenditures (a), energy footprint (b), and carbon footprint (c) per decile. Energy intensity as energy footprint per expenditure (d), carbon intensity as carbon footprint per expenditure (e), and carbon intensity as carbon footprint per energy footprint (f)."}
Figures 1d-e show that energy and carbon intensities are particularly high in the lower four deciles, while the higher deciles do not show large differences in weighted average energy and carbon intensity. The different intensities of household consumption across European expenditure deciles can be attributed to a combination of two plausible causes: first, if the the composition of consumption baskets systematically differs according to the level of household expenditure. Second, if energy and carbon intensity within individual consumption sectors systematically differs according to the level of household expenditure.
Figures 1d-e show that energy and carbon intensities of consumption are particularly high in the lower four deciles, while the higher deciles do not show large differences in weighted average energy and carbon intensity. The different intensities of household consumption across European expenditure deciles can be attributed to a combination of two plausible causes: first, if the composition of consumption baskets systematically differs according to the level of household expenditure. Second, if energy and carbon intensity within individual consumption sectors systematically differs according to the level of household expenditure.
Our data show that both of these factors play a role \@ref(fig:figure2). Poorer households on average, spend larger shares of their expenditure in the shelter sector. The bottom and top deciles spend an average of `r exp_share_shelter_bottom_decile`% and `r exp_share_shelter_top_decile`% of their household expenditures on shelter, respectively. Overall, with increasing expenditure decile, the shares of transport and services expenditures increase and the shares of shelter, food and manufactured goods decrease. At the same time, shelter is by far the most carbon intensive sector with the highest variance between expenditure deciles. In our sample, the intensity of all sectors decreases with expenditure level but the shelter sector stands out with a carbon intensity that is more than 3 times higher in the bottom decile (`r int_co2eq_shelter_bottom_decile` kgCO2eq/€) than in the top decile (`r int_co2eq_shelter_top_decile` kgCO2eq/€). Households in the top decile spend about `r exp_share_services_top_decile`% in the service sector that has the lowest carbon intensity, compared to `r exp_share_services_bottom_decile`% in the bottom decile (we have included the EXIOBASE production sector 'real estate services' in our aggregated 'services' sector, not the aggregated 'shelter' sector). Single country studies using MRIO models with national resolution can pick up on differences in consumption baskets but due to the homogeneous technology assumption cannot represent differences in technology between expenditure deciles.
Our data show that both of these factors play a role \@ref(fig:figure2). Poorer households on average, spend larger shares of their expenditure in the shelter sector. The bottom and top deciles spend an average of `r exp_share_shelter_bottom_decile`% and `r exp_share_shelter_top_decile`% of their household expenditures on shelter, respectively. Overall, with increasing expenditure decile, the shares of transport and services expenditures increase and the shares of shelter, food and manufactured goods decrease. At the same time, shelter is by far the most carbon intensive sector with the highest variance between expenditure deciles. In our sample, the intensity of all sectors decreases with expenditure level but the shelter sector stands out with a carbon intensity that is more than 3 times higher in the bottom decile (`r int_co2eq_shelter_bottom_decile` kgCO2eq/€) than in the top decile (`r int_co2eq_shelter_top_decile` kgCO2eq/€). Households in the top decile spend about `r exp_share_services_top_decile`% in the service sector that has the lowest carbon intensity, compared to `r exp_share_services_bottom_decile`% in the bottom decile (we have included the EXIOBASE production sector 'real estate services' in our aggregated 'services' sector, not the aggregated 'shelter' sector - see SI Table 4). Single country studies using MRIO models with national resolution can pick up on differences in consumption baskets but due to the homogeneous technology assumption cannot represent differences in technology between expenditure deciles.
The tendency that the emission intensity for direct energy consumption decreases with increasing affluence can be observed at the global level (XXX) between countries and also applies within Europe. In some of the Eastern European countries, between 80% and 100% of the population belong to the four lowest European expenditure deciles. This compares to less than 20% of the population in the richer European countries (Scandinavia, Germany, France, Austria, the Netherlands, Belgium, the UK, and Ireland). Note here that our analysis is based on average expenditure data from five income groups at the national level. This aggregation cuts off the lower and upper ends of the respective national expenditure distributions (Supplementary Note and Map).
The tendency that the emission intensity for direct energy consumption decreases with increasing affluence can be observed at the global level (XXX) between countries and also applies within Europe. In some of the Eastern European countries, between 80% and 100% of the population belong to the four lowest European expenditure deciles. This compares to less than 20% of the population in the richer European countries (Scandinavia, Germany, France, Austria, the Netherlands, Belgium, the UK, and Ireland). Note here that our analysis is based on average expenditure data from five income groups at the national level. This aggregation cuts off the lower and upper ends of the respective national expenditure distributions (Supplementary Note and Map).
