## 3 Results and Discussion
### Historical CH\({}_{4}\) Emission from MSW and Industrial Waste and Predicted Future Emission  
The results of calculations of methane emission from 1990 to 2050 are presented in Figure 5. Methane emission from MSW and industrial waste is presented separately to facilitate a clear understanding of the contributions made by the municipal and industrial \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & \multicolumn{4}{c}{**Short-Run GC–F Statistics**} & \multicolumn{4}{c}{**Long-Run GC-\(t\) Statistics**} \\ \hline  & **Ln (ISW)** & **Ln (GDPFC)** & **Ln (UPOP)** & **Ln (FDI)** & **Ln (UR)** & **Error Correction Term (ECT)** \\ \hline Ln (ISW) & - & 15.69 *** (0.0003) & 0.68 (0.41) & 1.66 (0.20) & 0.48 (0.49) & 12.45 *** (0.000) \\ Ln (GDPPC) & 0.24 (0.63) & - & 4.00 ** (0.05) & 4.36 ** (0.04) & 1.63 (0.21) & 3.96 ** (0.003) \\ Ln (UPOP) & 0.59 (0.45) & 2.72 * (0.10) & - & 0.44 (0.51) & 3.76 * (0.06) & 0.82 (0.41) \\ Ln (FDI) & 4.15 ** (0.05) & 8.92 *** (0.004) & 1.80 (0.19) & - & 0.03 (0.87) & 1.29 (0.20) \\ Ln (UR) & 0.01 (0.91) & 0.25 (0.62) & 1.33 (0.25) & 1.09 (0.30) & - & \(-0.70\) (0.49) \\ \hline \hline \end{tabular} Note: Probability value ’\(p\)’ is presented in parenthesis, and ’ **, and *** show significance at 0.1, 0.05, and 0.001 levels, respectively.  
\end{table} 
Table 10: Model 2: Short- and long-run causality test results. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & \multicolumn{4}{c}{**Short-Run GC–F Statistics**} & \multicolumn{4}{c}{**Long-Run GC-\(t\) Statistics**} \\ \hline  & **Ln (MSW)** & **Ln (GDPFC)** & **Ln (UPOP)** & **Ln (FDI)** & **Ln (LR)** & **Error Correction Term (ECT)** \\ \hline Ln (MSW) & - & 9.55 *** (0.003) & 13.37 (0.0007) & 9.72 (0.003) & 1.33 (0.26) & \(-\)2.36 ** (0.02) \\ Ln (GDPFC) & 1.30 (0.26) & - & 1.62 (0.21) & 1.38 (0.25) & 0.54 (0.47) & 3.09 *** (0.003) \\ Ln (UPOP) & 3.02 * (0.09) & 4.07 * (0.05) & - & 0.24 (0.63) & 0.39 (0.53) & 3.66 ** (0.001) \\ Ln (FDI) & 3.31 * (0.08) & 9.05 *** (0.004) & 1.50 (0.23) & - & 7.26 *** (0.01) & \(-\)3.12 ** (0.003) \\ Ln (LR) & 0.06 (0.81) & 0.45 (0.51) & 0.08 (0.79) & 0.09 (0.76) & - & \(-\)1.15 (0.26) \\ \hline \hline \end{tabular} Note: Probability value ’\(p\)’ is presented in parenthesis, and ’ **, and *** show significance at 0.1, 0.05, and 0.001 levels, respectively.  
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Table 9: Model 1: Short- and long-run causality test results. waste sectors. Generally, an increasing pattern of methane emission from total waste was observed at an average annual rate of 5.53% between 1990 and 2019, and 5.13% between 2020 and 2050. Methane generation from total waste is projected to reach about 4000 Gg by the end of the year 2050, which is an increase of 370% compared to methane emitted in 2019. When considering only MSW, methane emission was impacted by the variation of the population. Figure 5 presents the historical methane emission (1990-2019) from MSW for medium variant population and that of the projected methane emission (2020 to 2050) for low, medium, and high variations of the population [39]. It was observed that both low and high variant populations caused a maximum of 5% variation (more specifically, 4.99% for low variant and 4.69% for high variant) in methane generation compared to the medium variant population. The maximum variation of methane generation due to population occurred in the year 2050. The variation of the population was considered one of the important factors in projecting methane emission due to its direct association in MSW generation and thus methane emission. Other factors, such as the fraction of DOC and waste component composition in MSW stream, are also important factors but are less likely to be varied in a wide range and impact methane generation [54]. It is interesting to observe that the methane emission from MSW and industrial waste was comparable until the year 2010 (Figure 5). However, in five years (i.e., in 2015), methane emission from the industrial sector increased more than 1.5 times that of municipal solid waste.