## 7 Conclusions  
This paper focuses on seaport decarbonisation towards net zero, looking at a broad picture. Based on the literature, the emission sources at seaports are categorised according to different criteria. For example, according to the sources' functionality, they are broadly classified into two types, e.g., stationary and non-stationary types. According to their emission responsibility, they are classified into three categories: emission scopes 1, 2, and 3. According to their geographic locations at seaports, they are classified into four categories: seaside, quayside and yardside, landslide interface, and landslide industry and support facility. These categorisations from different criteria provide a better understanding of the emission sources, e.g., why the emissions occur, who has the direct/indirect control of the emissions, and where they occur.  
Various emission reduction measures at seaports are identified through the literature review. We classify them into six structured categories: operational measures, technical measures, fuel and energy measures, infrastructure measures, digitalisation measures, and policy and collaboration measures. The first three categories have a direct impact on emission reduction, whereas the last three categories tend to support and facilitate the development and deployment of the solution measures in the first three categories. We present these solution measures as a set of two-dimensional matrices for each geographic location category. Six UK ports and three international ports are selected and their emission reduction practices and pathways towards net zero are discussed. Based on the case studies, literature review, and our domain knowledge, a time-phased roadmap of seaport decarbonisation to net zero is proposed, in which each emission reduction category is divided into three phases: 2025, 2030, and 2040, in a progressive process. The challenges and research opportunities of implementing the roadmap are discussed.  
Seaports can play an important role in the IMO's shipping net zero target as well as the world's carbon net zero challenge. Seaports are not only acting as transport hubs and logistics hubs in their traditional roles but also can be developed as trading hubs (especially for those freeports), energy hubs, and data hubs in their emerging roles. The proposed strategic roadmap offers a guideline to seaports to implement emission reduction strategies and transition to net zero from the system perspective, even though seaports differ in many aspects. Broadly, it can also provide a blueprint for various industries, as well as local and national governments, to reduce emissions and transition to a cleaner energy future.  
Further research could be conducted in the areas identified in the previous section on research opportunities. In addition, it is also interesting to examine theoretical frameworks that underpin port decarbonisation and barriers to solution measures. In this direction, economic theories related to investment in green technologies, social theories regarding community engagement and labour implications, and political theories associated with policy making and international cooperation could be explored.  
This research was funded by EPSRC, grant number EP/Y024605/1.  
The author thanks two reviewers for providing helpful and constructive comments that have significantly improved the paper. The author also thanks the support by the Impact Acceleration Accounts at the University of Liverpool.  
The author declares no conflict of interest.