This thesis attempts to describe and analyse the steps that shall be taken towards the decarbonisation of the shipping industry. In the global effort to reduce GHG and carbon emissions, there is great importance for the shipping industry to decarbonise and move forward into a greener future. For the purpose of this thesis, we have identified the new challenges that the shipping industry faces over the last decade. To this end we give an overall overview of the significant role of the IMO as a global standard-setting authority for the environmental performance of international shipping, analysing also the Initial Strategy of IMO for achieving the reduction of shipping GHG. In light of the above we also make reference to the regulatory context for the implementation of the Initial Strategy analysing its challenges and complexity, while we also present a discussion of the most common alternative marine fuels that could be use by the global shipping industry.