Driving factors of CO2 emissions in South American countries: An application of Seemingly Unrelated Regression model
Received date: 2024-02-19
Revised date: 2024-06-12
Accepted date: 2024-11-14
Online published: 2025-08-13
Gadir BAYRAMLI , Turan KARIMLI . [J]. Regional Sustainability, 2024 , 5(4) : 100182 . DOI: 10.1016/j.regsus.2024.100182
Carbon emissions have become a critical concern in the global effort to combat climate change, with each country or region contributing differently based on its economic structures, energy sources, and industrial activities. The factors influencing carbon emissions vary across countries and sectors. This study examined the factors influencing CO2 emissions in the 7 South American countries including Argentina, Brazil, Chile, Colombia, Ecuador, Peru, and Venezuela. We used the Seemingly Unrelated Regression (SUR) model to analyse the relationship of CO2 emissions with gross domestic product (GDP), renewable energy use, urbanization, industrialization, international tourism, agricultural productivity, and forest area based on data from 2000 to 2022. According to the SUR model, we found that GDP and industrialization had a moderate positive effect on CO2 emissions, whereas renewable energy use had a moderate negative effect on CO2 emissions. International tourism generally had a positive impact on CO2 emissions, while forest area tended to decrease CO2 emissions. Different variables had different effects on CO2 emissions in the 7 South American countries. In Argentina and Venezuela, GDP, international tourism, and agricultural productivity significantly affected CO2 emissions. In Colombia, GDP and international tourism had a negative impact on CO2 emissions. In Brazil, CO2 emissions were primarily driven by GDP, while in Chile, Ecuador, and Peru, international tourism had a negative effect on CO2 emissions. Overall, this study highlights the importance of country-specific strategies for reducing CO2 emissions and emphasizes the varying roles of these driving factors in shaping environmental quality in the 7 South American countries.
Table 1 Description of the selected variables. |
| Variable | Unit | Description | Data sources |
|---|---|---|---|
| CO2 emissions | 103 t | The total amount of CO2 emissions | World Bank (2023) |
| Gross domestic product (GDP) | USD | The total value of all final goods and services produced by a country or region in a given period of time | |
| Renewable energy use | % | Percentage of the total final energy use | |
| Urbanization | persons | Number of urban population | |
| Industrialization | % | Industrial value added as a percentage of GDP | |
| International tourism | persons | Number of tourist arrivals | |
| Agricultural productivity | % | Agricultural value added as a percentage of GDP | |
| Forest area | km2 | - |
Note: - means no description. |
Fig. 1. Conceptual framework of the empirical research. |
Table 2 Descriptive statistics of the selected variables. |
| Variable | Mean | Minimum | Maximum | Standard Deviation |
|---|---|---|---|---|
| CO2 emissions (×108 t) | 1.306 | 0.221 | 5.116 | 1.208 |
| GDP (×1011 USD) | 5.130 | 0.663 | 36.300 | 7.720 |
| Renewable energy use (%) | 25.475 | 7.650 | 50.050 | 11.982 |
| Urbanization (×107 persons) | 4.470 | 0.761 | 18.900 | 5.130 |
| Industrialization (%) | 31.244 | 18.189 | 53.089 | 7.759 |
| International tourism (×107 persons) | 0.331 | 0.043 | 0.762 | 0.218 |
| Agricultural productivity (%) | 6.283 | 3.275 | 15.405 | 2.126 |
| Forest area (km2) | 1,083,250 | 124,335 | 5,510,886 | 1,683,224 |
Table 3 Correlation matrix of the error terms for the 7 South American countries. |
| Model 1 | Model 2 | Model 3 | Model 4 | Model 5 | Model 6 | Model 7 | |
|---|---|---|---|---|---|---|---|
| Model 1 | 1.000 | ||||||
| Model 2 | -0.043 | 1.000 | |||||
| Model 3 | -0.244 | 0.482 | 1.000 | ||||
| Model 4 | -0.275 | 0.107 | -0.223 | 1.000 | |||
| Model 5 | -0.159 | -0.481 | -0.237 | 0.554 | 1.000 | ||
| Model 6 | -0.135 | 0.229 | 0.732 | -0.089 | 0.219 | 1.000 | |
| Model 7 | 0.305 | -0.406 | 0.095 | -0.396 | 0.330 | 0.431 | 1.000 |
| Breusch-Pagan Lagrange Multiplier test: Chi2(45)=340.781; P-value=0.000 | |||||||
Note: Models 1-7 mean that the Seemingly Unrelated Regression (SUR) model was used to Argentina, Brazil, Chile, Colombia, Ecuador, Peru, and Venezuela, respectively. |
Table 4 Variance inflation factor (VIF) statistic values of the independent variables. |
| Independent variable | VIF | 1/VIF | Mean VIF |
|---|---|---|---|
| GDP | 4.566 | 0.219 | 2.534 |
| Renewable energy use | 3.215 | 0.311 | |
| Urbanization | 2.841 | 0.352 | |
| Industrialization | 2.212 | 0.452 | |
| International tourism | 2.203 | 0.454 | |
| Agricultural productivity | 1.531 | 0.653 | |
| Forest area | 1.200 | 0.833 |
Table 5 Cross-dectional dependence test results of the selected variables. |
| Variable | Cross-sectional dependence test | P-value | Variable | Cross-sectional dependence test | P-value |
|---|---|---|---|---|---|
| CO2 emissions | 13.944 | 0.000 | Industrialization | 8.893 | 0.000 |
| GDP | 11.891 | 0.000 | International tourism | 11.664 | 0.000 |
| Renewable energy use | 11.092 | 0.000 | Agricultural productivity | 3.825 | 0.000 |
| Urbanization | 20.613 | 0.000 | Forest area | 9.316 | 0.000 |
Table 6 Overall statistical significance of the 7 models. |
| Model | RMSE | R2 | Chi2 | P-value | Model | RMSE | R2 | Chi2 | P-value |
|---|---|---|---|---|---|---|---|---|---|
| Model 1 | 0.030 | 0.945 | 444.482 | 0.000 | Model 5 | 0.023 | 0.987 | 1847.552 | 0.000 |
| Model 2 | 0.016 | 0.989 | 2180.511 | 0.000 | Model 6 | 0.025 | 0.991 | 3178.612 | 0.000 |
| Model 3 | 0.056 | 0.933 | 337.414 | 0.000 | Model 7 | 0.054 | 0.949 | 524.887 | 0.000 |
| Model 4 | 0.046 | 0.898 | 205.637 | 0.000 |
Note: RMSE, Root Mean Square Error. |
Table 7 Estimation result of the Seemingly Unrelated Regression (SUR) model for the 7 South American countries. |
| Country | Dependent variable | Independent variable | Coefficient | Z-value | P-value | |
|---|---|---|---|---|---|---|
| Argentina | CO2 emissions | GDP | 0.253 | 2.426 | 0.016 | |
| Renewable energy use | -0.014 | -2.045 | 0.042 | |||
| Urbanization | 0.009 | 1.741 | 0.089 | |||
| Industrialization | 0.024 | 3.868 | 0.000 | |||
| International tourism | 4.102 | 6.992 | 0.000 | |||
| Agricultural productivity | 0.054 | 0.723 | 0.473 | |||
| Forest area | -7.747 | -6.476 | 0.000 | |||
| Constant | 10.505 | 7.026 | 0.000 | |||
| Brazil | CO2 emissions | GDP | 0.002 | 2.354 | 0.018 | |
| Renewable energy use | -0.033 | -18.612 | 0.000 | |||
| Urbanization | 0.009 | 2.139 | 0.033 | |||
| Industrialization | 0.007 | 1.151 | 0.252 | |||
| International tourism | -0.480 | -2.850 | 0.039 | |||
| Agricultural productivity | -0.082 | -1.762 | 0.078 | |||
| Forest area | -6.413 | -5.474 | 0.000 | |||
| Constant | 11.115 | 4.288 | 0.000 | |||
| Chile | CO2 emissions | GDP | -0.003 | -0.832 | 0.404 | |
| Renewable energy use | -0.017 | -2.039 | 0.042 | |||
| Urbanization | 0.002 | 2.292 | 0.047 | |||
| Industrialization | 0.099 | 2.320 | 0.020 | |||
| International tourism | 1.643 | 2.911 | 0.037 | |||
| Agricultural productivity | -0.117 | -2.961 | 0.034 | |||
| Forest area | -6.312 | -1.893 | 0.059 | |||
| Constant | -34.991 | -2.887 | 0.004 | |||
| Colombia | CO2 emissions | GDP | 0.003 | 2.753 | 0.045 | |
| Renewable energy use | -0.002 | -4.180 | 0.024 | |||
| Urbanization | 0.025 | 3.533 | 0.000 | |||
| Industrialization | 0.107 | 4.074 | 0.000 | |||
| International tourism | 0.723 | 4.446 | 0.000 | |||
| Agricultural productivity | -0.051 | -1.558 | 0.120 | |||
| Forest area | -1.035 | -4.673 | 0.004 | |||
| Constant | 0.816 | 0.281 | 0.779 | |||
| Ecuador | CO2 emissions | GDP | -0.002 | -3.193 | 0.014 | |
| Renewable energy use | -0.039 | -16.021 | 0.000 | |||
| Urbanization | 0.003 | 1.669 | 0.097 | |||
| Industrialization | 0.007 | 2.465 | 0.044 | |||
| International tourism | 0.543 | 3.574 | 0.069 | |||
| Agricultural productivity | -0.158 | -3.435 | 0.001 | |||
| Forest area | -1.417 | -4.385 | 0.017 | |||
| Constant | 16.593 | 0.289 | 0.778 | |||
| Peru | CO2 emissions | GDP | -0.001 | -2.852 | 0.040 | |
| Renewable energy use | -0.052 | -16.241 | 0.000 | |||
| Urbanization | 0.004 | 2.267 | 0.021 | |||
| Industrialization | 0.007 | 0.423 | 0.676 | |||
| International tourism | 0.036 | 3.040 | 0.024 | |||
| Agricultural productivity | -0.003 | -2.145 | 0.041 | |||
| Forest area | -1.604 | -3.223 | 0.026 | |||
| Constant | 34.584 | 0.386 | 0.765 | |||
| Venezuela | CO2 emissions | GDP | 0.001 | 3.393 | 0.069 | |
| Renewable energy use | -0.045 | -9.274 | 0.000 | |||
| Urbanization | 0.002 | 3.557 | 0.058 | |||
| Industrialization | 0.012 | 4.479 | 0.035 | |||
| International tourism | 3.781 | 10.273 | 0.000 | |||
| Agricultural productivity | 0.078 | 2.072 | 0.038 | |||
| Forest area | -12.409 | -8.488 | 0.000 | |||
| Constant | -24.935 | -8.834 | 0.000 | |||
Table 8 Estimation results of the SUR model for the independent variables. |
| Independent variable | Coefficient | Standard error | t-statistic | Independent variable | Coefficient | Standard error | t-statistic |
|---|---|---|---|---|---|---|---|
| Forest area | -5.277 | 0.568 | -9.284*** | Renewable energy use | -0.029 | 0.010 | -2.843*** |
| International tourism | 1.401 | 0.151 | 9.309*** | Urbanization | 0.008 | 0.002 | 5.193*** |
| Industrialization | 0.038 | 0.015 | 2.577*** | Agricultural productivity | -0.040 | 0.075 | -0.532 |
| GDP | 0.036 | 0.015 | 2.385*** | Constant | 1.955 | 18.612 | 0.105 |
Note: *** denotes statistical significance at the P≤0.01 level. |
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