# Forecast Analysis of Pollutant Emissions of Cruise Ship Routes in Western Mediterranean
## 4 Results
### Forecast Analysis of Gas Emissions  
From the results obtained in Section 4.2, it would be interesting to analyse the evolution of gas emissions over time, considering factors of the evolution of cruise traffic and the implementation of new regulations about gas emissions. Therefore, several projections were made to forecast the gas emissions in the Western Mediterranean for the period of 2023-2025, taking as a reference the estimated emissions for the year 2019. Five scenarios were assessed. The first scenario (named optimistic scenario) considers growth for the entire period equaling the average growth in terms of connections before the COVID pandemic (period of 2017-2019), up to 5.3%, until the implementation of the SECA. The second scenario (named realistic scenario) considers growth equal to 5.3% for the first year and 2.5% for the rest of the period until the implementation of the SECA. The third scenario (named stagnation scenario 1) considers a growth equal to 5.3% for the first year and no growth for the remaining years until the implementation of the SECA. The fourth scenario (named stagnation scenario 2) considers a growth equal to 2.5% for the first year and no growth for the remaining years until the implementation of the SECA. The fifth scenario (named pessimistic scenario) does not consider growth for the first year and assumes a decrease of 2.5% for the rest of the period until the implementation of the SECA. The connection growth for each route is determined based on the total number of connections for the reference year; that is,  
\[NCR_{i}=NCR_{i-1}+CR\cdot NCG, \tag{2}\]  
\(NCR\) is the number of connections per route in the year \(i\), \(CR\) is the connection rate determined as \(NCR/TNC\), where \(TNC\) is the total number of connections in the year \(i\), and \(NCG\) is the total number of connections grown in the year \(i\). Emissions are calculated as \(TE/\)_nautical mile_, where \(TE\) is tons emitted, which is determined as \(TNE/TNC\cdot D\), where \(TNE\) is the total number of emissions for the year 2019, and \begin{table}
\begin{tabular}{l c c c c c c} \hline \hline \multirow{2}{*}{**Cruise Route**} & \multirow{2}{*}{\begin{tabular}{c} **No. of** \\ **Connections** \\ \end{tabular} } & \multirow{2}{*}{\
\begin{tabular}{c} **Distance** \\ **(nm)** \\ \end{tabular} } & \multicolumn{4}{c}{**Emissions**} \\ \cline{4-7}  & & & **NOx (t)** & **SO2 (t)** & **CO2 (t)** &
\begin{tabular}{c} **Average** \\ **Share (\%)** \\ \end{tabular} \\ \hline Malaga–Funchal & 38 & 673 & 683.7 & 119.2 & 37,799.2 & 2.6 \\ Gibraltar–Southampton & 37 & 1145 & 1272.4 & 222.1 & 70,411.6 & 4.9 \\ Gibraltar–Lisbon & 27 & 303 & 185.3 & 31.8 & 10,483.3 & 0.7 \\ Malaga–Lisbon & 17 & 362 & 183.2 & 32.1 & 10,188.4 & 0.7 \\ Gibraltar–Arrecife de Lanzarote & 9 & 605 & 120.1 & 20.7 & 6549.9 & 0.5 \\ Santa Cruz de Tenerife–Malaga & 9 & 789 & 181.3 & 31.3 & 11,211.9 & 0.7 \\ Southampton–Malaga & 8 & 1281 & 202.2 & 35.5 & 11,247.6 & 0.8 \\ Funchal–Barcelona & 5 & 1131 & 85.7 & 15.0 & 4764.2 & 0.3 \\ Gibraltar–Funchal & 5 & 624 & 43.3 & 6.9 & 2200.2 & 0.2 \\ Ponta Delgada–Malaga & 5 & 1058 & 113.9 & 20.0 & 6335.5 & 0.4 \\ \hline \hline \end{tabular} Source: Authors’ elaboration.  
\end{table} 
Table 8: Distance, number of connections, and emissions associated with the repositioning routes identified. is the sailing distance of the route. The forecasted gas emissions per year and per route are as follows:  
\[TNE_{i}=\sum_{i}^{m}\sum_{j}^{n}\left(\frac{TE_{j}}{nautical\ mile}\right)_{2019} \cdot TNC_{i}D_{j}, \tag{3}\]  
where \(i\) is the year under study and \(j\) is the route considered. Figure 5 shows the results of the projections for the five aforementioned scenarios for pollutant gas emissions. The emissions associated with 2022 are the baseline for projections, which corresponds to the emissions for 2019, applying a cruise ship activity-based approach.