3.1. Empirical Results
The analysis presented above is applied to the case of the Greek economy, using a symmetric national I-O table and GHG emissions data for the year 2018. The described industries along with the data processing are reported in Table A.1 in Appendix A.
Table 1 reports the values of different types of total backward GHG emissions linkages and leakages. [see equations (17), (21), (24), (25), (27) and (29)]. To illustrate the practical implications of the estimated values, the first industry is used as an example. In this case, if the final demand for industry 1's domestically produced commodity increases by 1 million USD, it triggers a corresponding rise in the demand for its domestic intermediate inputs from both other industries and itself. As a result, the overall GHG emissions of the Greek economy increase by a total of 789 tCO2e. Notably, industry 1 absorbs the highest amount of GHG emissions from its own production, with 646 tCO2e (or 81.84%) attributed to the demand for domestic intermediate inputs from within the industry itself. Additionally, industry 1 absorbs 143 tCO2e (or 18.16%) of emissions resulting from its demand for domestic intermediate inputs sourced from other industries. By examining the plot of the matrix \(\varvec{\Phi }\) [see Figure B.1(a) in Appendix B], it becomes apparent that industry 15 plays a crucial role in contributing to these external emissions, accounting for 69.99 tCO2e (or 48.82%). Additionally, significant contributions are observed from industries 19 and 16, accounting for 26.46 tCO2e (or 18.46%) and 14.51 tCO2e (or 10.12%), respectively. The remaining industries contribute 32.39 tCO2e (or 22.59%) to the total external backward GHG emissions linkages.
In relation to the backward leakage of GHG emissions, an increase of 1 million USD in the final demand for industry 1's domestically produced commodity stimulates a higher demand for its imported inputs from all industries, including itself. As a result, there is an additional increase of 65.2 tCO2e in the overall GHG emissions of the economy. Industry 1 absorbs 12.83 tCO2e (or 19.69%) through its demand for its own imported inputs and 52.34 tCO2e (or 80.31%) through its demand for imports obtained from other industries. Based on the plot of the matrix \(\varvec{\Gamma }\) [see Figure B.2(a) in Appendix B], it becomes evident that industry 2 holds a prominent position in the external emissions leakages, accounting for 13.33 tCO2e (or 25.46%). Additionally, notable contributions are observed from industry 7, representing 10.00 tCO2e (or 19.10%), and industry 19, contributing 7.96 tCO2e (or 15.20%). The remaining industries contribute 21.06 tCO2e (or 40.23%) to the total external backward GHG emissions leakages.
Table 1
The total backward GHG emissions linkages and leakages.
| Industry \(j\) or\(i\) | \({BLINK}_{j}\) | \({BLINK}_{j}^{I}\) | \({BLINK}_{j}^{E}\) | \({BLEAK}_{j}\) | \({BLEAK}_{j}^{I}\) | \({BLEAK}_{j}^{E}\) |
| 1 | 789 (6) | 646 (6) | 143 (17) | 65.2 (13) | 12.83 (6) | 52.34 (17) |
| 2 | 775 (7) | 688 (5) | 86.01 (23) | 30.9 (23) | 10.13 (8) | 20.81 (25) |
| 3 | 538 (9) | 194 (10) | 343 (3) | 81.4 (9) | 3.32 (10) | 78.10 (6) |
| 4 | 242 (14) | 5.05 (24) | 236 (7) | 74.2 (12) | 0.57 (13) | 73.65 (9) |
| 5 | 236 (15) | 50.92 (12) | 184 (11) | 60.7 (15) | 7.06 (9) | 53.63 (15) |
| 6 | 377 (10) | 292 (9) | 84.80 (25) | 419 (1) | 11.74 (7) | 407 (6) |
| 7 | 684 (8) | 535 (7) | 148 (15) | 123 (5) | 61.32 (2) | 62.25 (11) |
| 8 | 205 (16) | 19.91 (16) | 184 (12) | 57.0 (17) | 0.31 (15) | 56.67 (13) |
| 9 | 2,163 (2) | 1,902 (2) | 260 (5) | 153 (2) | 52.16 (4) | 101 (5) |
| 10 | 1,007 (4) | 317 (8) | 688 (2) | 135 (3) | 59.64 (3) | 75.71 (8) |
| 11 | 306 (12) | 50.89 (13) | 254 (6) | 108 (7) | 1.18 (12) | 107 (3) |
| 12 | 258 (13) | 46.90 (14) | 211 (8) | 108 (8) | 2.51 (11) | 105 (4) |
| 13 | 170 (21) | 6.16 (23) | 163 (14) | 77.1 (10) | 0.13 (16) | 76.93 (7) |
| 14 | 173 (20) | 4.40 (25) | 168 (13) | 64.0 (14) | 0.02 (23) | 63.94 (10) |
| 15 | 3,529 (1) | 3,467 (1) | 61.82 (26) | 74.9 (11) | 19.90 (5) | 54.96 (14) |
| 16 | 1,981 (3) | 1,288 (3) | 692 (1) | 53.0 (18) | 0.05 (17) | 52.98 (16) |
| 17 | 368 (11) | 46.64 (15) | 321 (4) | 118 (6) | 0.05 (18) | 118 (2) |
| 18 | 182 (19) | 58.63 (11) | 123 (20) | 59.3 (16) | 0.48 (14) | 58.82 (12) |
| 19 | 846 (5) | 738 (4) | 107 (21) | 128 (4) | 78.90 (1) | 49.27 (19) |
| 20 | 200 (17) | 7.07 (19) | 192 (9) | 50.6 (19) | 7x\({10}^{-4}\) (25) | 50.65 (18) |
| 21 | 143 (24) | 2.58 (28) | 140 (18) | 35.4 (22) | 0.04 (19) | 35.32 (22) |
| 22 | 34.4 (29) | 0.96 (29) | 33.48 (29) | 6.1 (30) | 0.04 (20) | 6.10 (30) |
| 23 | 32.1 (30) | 0.04 (30) | 31.92 (30) | 10.5 (28) | \({10}^{-6}\) (30) | 10.49 (28) |
| 24 | 91.7 (26) | 6.78 (21) | 84.94 (24) | 27.3 (24) | 0.02 (22) | 27.25 (23) |
| 25 | 143 (23) | 6.77 (22) | 136 (19) | 38.8 (21) | 0.03 (21) | 38.73 (21) |
| 26 | 66.6 (27) | 11.24 (17) | 55.41 (27) | 12.0 (27) | 5x\({10}^{-4}\) (27) | 11.96 (27) |
| 27 | 55.5 (28) | 2.83 (27) | 52.70 (28) | 8.1 (29) | 3x\({10}^{-5}\) (29) | 8.05 (29) |
| 28 | 96.3 (25) | 4.06 (26) | 92.28 (22) | 27.2 (25) | 6x\({10}^{-4}\) (26) | 27.17 (24) |
| 29 | 158 (22) | 9.32 (18) | 148 (16) | 19.0 (26) | 0.02 (24) | 19.02 (26) |
| 30 | 192 (18) | 6.87 (20) | 185 (10) | 41.8 (20) | 2x\({10}^{-4}\)(28) | 41.77 (20) |
| Note: The numbers in parenthesis represent the ranking of the industry. |
Table 2 reports the values of different types of total forward GHG emissions linkages and leakages. [see equations (19), (23), (24), (26), (20) and (30)]. Specifically, when the value added of the domestically produced commodity in industry 1 increases by 1 million USD, it results in a higher supply of its domestic intermediate inputs to all other industries, including itself. This leads to a total increase of 705 tCO2e in the GHG emissions of the entire economy. Similar to the backward linkages, industry 1 plays a significant role as the primary transmitter of GHG emissions from its own production. Precisely, it transfers 646 tCO2e (or 91.62%) through the supply of its domestic intermediate inputs to itself. Additionally, it transfers 59.09 tCO2e (or 8.38%) through the supply of domestic intermediate inputs to the other industries. Based on the plot of the matrix \(\varvec{\Psi }\) [see Figure B.1(b) in Appendix B], noteworthy contributions in these external forward GHG emissions linkages come from industry 3, accounting for 48.51 tCO2e (or 82.09%), and industry 15, contributing 3.50 tCO2e (or 5.92%). The remaining industries contribute 7.08 tCO2e (or 11.98%) to the external forward GHG emissions linkages.
In terms of the forward leakage of GHG emissions, an increase of 1 million USD in the value added of industry 1's domestically produced commodity stimulates a higher supply of its imported inputs to all industries, including itself. Consequently, there is an additional increase of 25.2 tCO2e in the overall GHG emissions of the economy. Industry 1 transfers 13.60 tCO2e (or 54.05%) through its supply of its own imported inputs, while 11.56 tCO2e (or 45.95%) is transferred through its supply of imports to other industries. Based on the plot of the matrix \(\varvec{\Delta }\) [see Figure B.2(b) in Appendix B], industry 3 has a notable impact on the external emissions leakages, accounting for 8.30 tCO2e (or 71.77%). Finally, the remaining industries contribute 3.27 tCO2e (or 28.23%) to the overall external forward GHG emissions leakages.
Table 2
The total forward GHG emissions linkages and leakages.
| Industry \(j\) or\(i\) | \({FLINK}_{i}\) | \({FLINK}_{i}^{I}\) | \({FLINK}_{i}^{E}\) | \({FLEAK}_{i}\) | \({FLEAK}_{i}^{I}\) | \({FLEAK}_{i}^{E}\) |
| 1 | 705 (6) | 646 (6) | 59.09 (19) | 25.2 (19) | 13.60 (7) | 11.56 (22) |
| 2 | 957 (4) | 688 (5) | 268 (1) | 2,672 (1) | 4.96 (9) | 2,667 (1) |
| 3 | 224 (11) | 194 (10) | 28.85 (23) | 12.9 (23) | 3.09 (10) | 9.84 (24) |
| 4 | 31.2 (26) | 5.05 (24) | 26.17 (25) | 36.2 (17) | 0.57 (14) | 35.68 (15) |
| 5 | 190 (16) | 50.92 (12) | 138 (10) | 74.1 (13) | 7.05 (8) | 67.03 (10) |
| 6 | 510 (8) | 292 (9) | 217 (4) | 149 (4) | 13.78 (6) | 135 (4) |
| 7 | 632 (7) | 535 (7) | 95.98 (14) | 467 (2) | 60.48 (2) | 407 (2) |
| 8 | 43.2 (24) | 19.91 (16) | 23.32 (26) | 34.6 (18) | 0.31 (16) | 34.26 (16) |
| 9 | 2,024 (2) | 1,902 (2) | 120 (12) | 116 (6) | 50.79 (4) | 65.94 (11) |
| 10 | 367 (9) | 317 (8) | 49.60 (22) | 104 (8) | 59.26 (3) | 45.58 (13) |
| 11 | 217 (13) | 50.89 (13) | 166 (7) | 77.5 (10) | 1.26 (12) | 76.22 (7) |
| 12 | 113 (19) | 46.90 (14) | 66.59 (18) | 193 (3) | 2.39 (11) | 191 (3) |
| 13 | 107 (20) | 6.16 (23) | 101 (13) | 129 (5) | 0.13 (17) | 129 (5) |
| 14 | 206 (15) | 4.40 (25) | 201 (6) | 86.0 (9) | 0.02 (23) | 85.98 (6) |
| 15 | 3,724 (1) | 3,467 (1) | 256 (2) | 57.8 (14) | 23.91 (5) | 33.93 (17) |
| 16 | 1,371 (3) | 1,288 (3) | 81.98 (16) | 14.5 (22) | 0.47 (15) | 14.00 (21) |
| 17 | 98.8 (21) | 46.64 (15) | 52.13 (21) | 10.1 (24) | 0.07 (18) | 10.05 (23) |
| 18 | 224 (12) | 58.63 (11) | 164 (8) | 51.0 (15) | 0.65 (13) | 50.39 (12) |
| 19 | 829 (5) | 738 (4) | 90.38 (15) | 111 (7) | 78.54 (1) | 33.15 (18) |
| 20 | 17.4 (28) | 7.07 (19) | 10.29 (28) | 1.7 (29) | 3x\({10}^{-3}\) (26) | 1.67 (29) |
| 21 | 80.1 (22) | 2.58 (28) | 77.42 (17) | 21.8 (20) | 0.04 (19) | 21.74 (19) |
| 22 | 210 (14) | 0.96 (29) | 208 (5) | 75.9 (11) | 0.04 (20) | 75.83 (8) |
| 23 | 128 (18) | 0.04 (30) | 127 (11) | 16.1 (21) | 2x\({10}^{-5}\) (30) | 16.14 (20) |
| 24 | 253 (10) | 6.78 (21) | 246 (3) | 74.7 (12) | 0.03 (21) | 74.69 (9) |
| 25 | 159 (17) | 6.77 (22) | 152 (9) | 39.8 (16) | 0.03 (22) | 39.79 (14) |
| 26 | 38.9 (25) | 11.24(17) | 27.71 (24) | 4.0 (27) | 4x\({10}^{-3}\) (25) | 3.99 (27) |
| 27 | 10.1 (29) | 2.83 (27) | 7.29 (29) | 2.1 (28) | 1x\({10}^{-4}\) (29) | 2.12 (28) |
| 28 | 8.8 (30) | 4.06 (26) | 4.74 (30) | 0.8 (30) | 1x\({10}^{-3}\) (28) | 0.85 (30) |
| 29 | 26.7 (27) | 9.32 (18) | 17.40 (27) | 5.6 (26) | 0.02 (24) | 5.61 (26) |
| 30 | 63.5 (23) | 6.87 (20) | 56.63 (20) | 6.0 (25) | 1x\({10}^{-3}\) (27) | 6.04 (25) |
| Note: The numbers in parenthesis represent the ranking of the industry. |
Table 3 reports the values of the relative GHG emissions linkages and leakages [see equations (31) to (34)]. In relation to the relative emissions linkages, if the direct GHG emissions intensity increases by 1 tCO2e, due to an increase in its final demand, the total increase in the GHG emissions within the Greek economy is expected to be 1.4 tCO2e. This rise of 1.4 units comprises a one-unit increase from direct emissions and an additional increase of: \(1.4-1=0.4\) units sourced from indirect emissions changes throughout the economy, triggered by interconnected industry activities. Furthermore, when focusing on the impact of changes in value added, a unit increase in the direct GHG emissions intensity of industry 1 results in a total increase of 1.2 tCO2e in GHG emissions. This signifies that a unit increase in industry 1's direct emissions intensity induces an additional increase of: \(1.2-1=0.2\) units of indirect GHG emissions.
Table 3
The relative backward and forward GHG emissions linkages and leakages.
| Industry \(j\) or\(i\) | \({BLINK}_{j}^{R}\) | \({FLINK}_{i}^{R}\) | \({BLEAK}_{j}^{R}\) | \({FLEAK}_{i}^{R}\) |
| 1 | 1.4 (24) | 1.2 (26) | 0.11 (26) | 0.04 (28) |
| 2 | 1.3 (28) | 1.6 (22) | 0.05 (28) | 4.41 (13) |
| 3 | 2.9 (22) | 1.2 (27) | 0.44 (23) | 0.07 (26) |
| 4 | 48.6 (3) | 6.3 (9) | 14.94 (2) | 7.29 (7) |
| 5 | 5.5 (19) | 4.4 (11) | 1.41 (19) | 1.72 (11) |
| 6 | 1.4 (26) | 1.8 (21) | 1.49 (18) | 0.53 (19) |
| 7 | 1.3 (27) | 1.2 (28) | 0.23 (24) | 0.89 (15) |
| 8 | 10.3 (14) | 2.2 (18) | 2.88 (12) | 1.75 (10) |
| 9 | 1.2 (30) | 1.1 (29) | 0.09 (27) | 0.07 (27) |
| 10 | 3.5 (20) | 1.3 (25) | 0.47 (22) | 0.37 (20) |
| 11 | 6.3 (16) | 4.5 (10) | 2.25 (17) | 1.61 (12) |
| 12 | 5.5 (18) | 2.4 (17) | 2.33 (15) | 4.17 (9) |
| 13 | 27.7 (8) | 17.5 (7) | 12.58 (5) | 21.20 (3) |
| 14 | 39.9 (4) | 47.4 (3) | 14.72 (3) | 19.79 (4) |
| 15 | 1.3 (29) | 1.3 (24) | 0.03 (30) | 0.02 (29) |
| 16 | 1.6 (23) | 1.1 (30) | 0.04 (29) | 0.01 (30) |
| 17 | 8.1 (15) | 2.2 (20) | 2.61 (14) | 0.22 (23) |
| 18 | 3.3 (21) | 4.0 (12) | 1.06 (21) | 0.92 (14) |
| 19 | 1.4 (25) | 1.3 (23) | 0.21 (25) | 0.18 (25) |
| 20 | 28.3 (6) | 2.5 (16) | 7.18 (6) | 0.24 (22) |
| 21 | 59.1 (2) | 33.2 (5) | 14.65 (4) | 9.02 (6) |
| 22 | 38.8 (5) | 236 (2) | 6.92 (7) | 85.48 (2) |
| 23 | 900 (1) | 3,599 (1) | 295 (1) | 454 (1) |
| 24 | 14.3 (13) | 39.5 (4) | 4.25 (11) | 11.65 (5) |
| 25 | 23.1 (10) | 25.7 (6) | 6.26 (9) | 6.43 (8) |
| 26 | 5.9 (17) | 3.5 (14) | 1.07 (20) | 0.36 (21) |
| 27 | 19.9 (11) | 3.6 (13) | 2.88 (13) | 0.76 (17) |
| 28 | 23.9 (9) | 2.2 (19) | 6.75 (8) | 0.21 (24) |
| 29 | 18.9 (12) | 3.2 (15) | 2.28 (16) | 0.68 (18) |
| 30 | 28.2 (7) | 9.3 (8) | 6.12 (10) | 0.89 (16) |
| Note: The numbers in parenthesis represent the ranking of the industry. |
In terms of relative emissions leakages, the substitution of imported intermediate inputs with domestically produced ones in industry 1 as well as a one-unit increase in its direct emissions intensity due to an increase in its final demand, would lead to a total increase of 0.11 tCO2e in the GHG emissions in the economy. This suggests that while the direct emissions increase is one unit, the process of replacing imported intermediate inputs with domestic ones generates a decrease of: \(0.11-1=-0.89\) units in GHG emissions elsewhere in the economy. This decrease is considered an indirect effect, potentially due to more efficient domestic production or superior supply chain practices. On the other hand, a one-unit increase in its direct GHG emissions intensity due to an increase in its value added, results in a total increase of only 0.04 tCO2e in the GHG emissions within the economy. This reflects indirect emissions decrease of: \(0.04-1=-0.96\) units.
3.2. Discussion
It is crucial to accurately understand and interpret the different types of indices related to emissions linkages and leakages. The total GHG emissions linkages indices capture the overall change in GHG emissions resulting from a one-unit change in the final demand (i.e., \({BLINK}_{j}\)) or value added (i.e., \({FLINK}_{i}\)) of domestically produced commodities, providing a comprehensive view of the direct and indirect effects of changes in economic activities on GHG emissions. In contrast, the indices for relative GHG emissions linkages focus on the change in total GHG emissions caused by a unit change in the direct emissions of industries, driven by an increase in the final demand (i.e., \({BLINK}_{j}^{R}\)) or value added (i.e., \({FLINK}_{i}^{R}\)) of their domestically produced commodities. These indices specifically investigate the indirect effects among interconnected industries, emphasizing the relationships and transmission of emissions between them.
The indices for emissions leakages evaluate how the substitution of imported intermediate inputs with domestic ones influences the economy's total GHG emissions. They assess the extent to which changes in GHG emissions are affected by this substitution and the associated interplay between intermediate imports and final demand or value added of domestically produced commodities. By considering the potential emissions reduction resulting from the use of domestic inputs, these indices shed light on the environmental implications of import substitution strategies. Specifically, total emissions leakages measure the absolute amount of GHG emissions that would occur if the imported intermediate inputs were replaced with domestically produced ones. This is due to a unit increase in the final demand (i.e., \({BLEAK}_{j}\)) or value added (i.e., \({FLEAK}_{i}\)) of a specific industry. On the other hand, relative emissions leakages are normalized measures that show how many times the industry's direct GHG emissions intensity would the total GHG emissions increase, due to a unit change in the direct emissions intensity of the industry induced by an increase in its final demand (i.e., \({BLEAK}_{j}^{R}\)) or value added (i.e., \({FLEAK}_{i}^{R}\)). These indicators provide an understanding of the emissions intensity associated with the industry, accounting for the indirect effects that come from changing the direct emissions intensity. It should be noted that when the values of the relative leakages are less than one, it signifies that the economy-wide increase in emissions is less than the direct increase in emissions intensity, due to indirect emissions reductions elsewhere in the economy. This highlights potential emissions reduction opportunities through the adoption of more efficient domestic production or superior supply chain practices.
Finally, understanding the internal emission linkages and leakages of an industry is essential for assessing its own production processes' contributions to GHG emissions. These internal indices (i.e., \({BLINK}_{j}^{I}, {BLEAK}_{j}^{I}, {FLINK}_{i}^{I}\)and \({FLEAK}_{i}^{I}\)) reveal the extent to which an industry's own activities generate emissions and provide insights into potential emission reduction opportunities through internal adjustments and improvements. External emission linkages and leakages (i.e., \({BLINK}_{j}^{E}, {BLEAK}_{j}^{E}, {FLINK}_{i}^{E}\)and \({FLEAK}_{i}^{E}\)) illuminate the emissions spillover effects between industries. These indices highlight the interdependencies among different sectors, emphasizing the importance of collaborative efforts in achieving sustainable emissions reduction.