# Forecast Analysis of Pollutant Emissions of Cruise Ship Routes in Western Mediterranean
## 1 Introduction
This work focuses on the emissions of polluting gases from cruise ships in the Western Mediterranean, specifically through an estimation of the emission inventory of NOx, SO\({}_{2}\), and CO\({}_{2}\) during navigation. \begin{table}
\begin{tabular}{l c c c c c c c c} \hline \hline  & & & & & & & Year & & \\ \hline
**Region** & **2015** & **2016** & **2017** & **2018** & **2019** & **2020** & **2021** & **2022** \\ \hline Western Mediterranean & 17.37 & 17.89 & 17.49 & 19.07 & 20.83 & 1.28 & 3.69 & 15.44 \\ Adriatic Sea & 4.49 & 4.70 & 4.45 & 4.89 & 5.43 & 0.03 & 0.84 & 3.02 \\ Eastern Mediterranean & 3.03 & 2.22 & 1.75 & 1.64 & 2.36 & 0.08 & 0.58 & 2.24 \\ Total & 24.89 & 24.81 & 23.69 & 25.60 & 28.62 & 1.39 & 5.11 & 20.70 \\ \hline \hline \end{tabular} Source: Authors’ elaboration based on [5; 11].  
\end{table} 
Table 1: Cruise passenger movements (in millions) per Mediterranean region from 2015 to 2022. \begin{table}
\begin{tabular}{l c c c c c c c} \hline \hline  & & & & Year & & & \\ \hline
**Region** & **2015** & **2016** & **2017** & **2018** & **2019** & **2020** & **2021** & **2022** \\ \hline Western Mediterranean & 6919 & 7251 & 6968 & 7394 & 7495 & 613 & 2512 & 7501 \\ Adriatic Sea & 2544 & 2919 & 2596 & 2683 & 3019 & 148 & 878 & 2553 \\ Eastern Mediterranean & 2197 & 1522 & 1148 & 1057 & 1550 & 129 & 779 & 2292 \\ Total & 11,660 & 11,692 & 10,712 & 11,134 & 12,064 & 890 & 4169 & 12,346 \\ \hline \hline \end{tabular} Source: Authors’ elaboration based on [5; 11].  
\end{table} 
Table 2: Cruise ship calls per Mediterranean region from 2015 to 2022. The Mediterranean Sea is almost totally enclosed by three continents and hosts intense cruise activity, as its performance indicators reflect; see Tables 1 and 2. The Western part stands out as it accounts for more than 70% of the cruise activity of the whole Mediterranean. The features of the cruise traffic in the Mediterranean as the second-largest cruise destination region worldwide, the high cruise activity registered in the Western Mediterranean, and the designation of its waters as an Emission Control Area in 2025 motivate research on the forecast of emissions from cruise ships during sailing on Western Mediterranean itineraries. This article aims to provide a gas emission inventory of cruise traffic in the Western Mediterranean as a basis for future policies and measures to be implemented on the horizon of the future enforcement of the SECA (Sulphur Emission Control Area) in the Mediterranean in 2025. To meet this goal, first, the cruise shipping network in the Western Mediterranean is analysed to identify the main routes, and next, through a bottom-up approach, the cruise activity of the main cruise routes is quantified as the basis to provide the estimation of the emission inventory. In addition, projections of the gas emissions from cruise activity in the Western Mediterranean are proposed for the time frame of 2023-2025 based on five scenarios that consider the evolution of the cruise traffic, the implementation of the SECA in the Mediterranean, and variations in the specific fuel consumption of cruise ships. Detailed inventories of cruise ship exhaust gas emissions can provide a scientific basis for making regulations to limit ship emissions, assess the current regulations, and/or take corrective action. The remainder of this article is organised as follows. The second section provides a literature review of analyses of shipping networks and methods to estimate shipping emission inventory. Section 3 explains the methodology applied in this research. Section 4 reports on the results of gas emission inventories associated with cruise routes in the Western Mediterranean and forecasts of emissions for the period of 2023-2025. Section 5 deals with the implications of the results and future research directions. Finally, Section 6 includes concluding remarks.