This report reviews port-based incentive schemes to reduce shipping emissions, such as environmentally differentiated port fees. Greenhouse gas emissions from shipping currently represent around 2.6% of total global emissions, but this share could more than triple by 2050. Ports have a crucial role to play in facilitating the reduction of shipping emissions, alongside the ship operators themselves. Which incentives are currently used? What are their impacts? How could positive effects be increased? The report also explores lessons learned that could inform international negotiations on the reduction of shipping greenhouse gas emissions.