Charting the Course to a Quiet Ocean
IMO Stakeholder Perspectives and Case Studies on Reducing Underwater Radiated Noise
Underwater noise levels are rising—yet the shipping sector’s contributions remain under-prioritized by the International Maritime Organization (IMO), the global regulator for international shipping. Equal Routes urges action with a new report, Charting the Course to a Quiet Ocean.
Background
The global shipping industry is the dominant source of anthropogenic underwater radiated noise (URN) in the world’s ocean¹. URN is a form of pollution that significantly impacts the environment, biodiversity, and people. To fully grasp the consequences of URN from ships, it is crucial to consider the unique environmental features of different geographic regions and the varying noise sensitivities of different species present there.
This understanding is especially vital in regions historically characterized by low levels of anthropogenic noise, such as Inuit Nunaat and the Arctic, which are now facing rising shipping traffic.
Although the harmful effects of URN have been acknowledged for decades, management and mitigation of ship-sourced URN remain largely fragmented and sectoral, lacking a single multilateral instrument that regulates all areas and sectors. The transboundary nature of URN pollution requires a coordinated international response that addresses current regulatory gaps.
In 2014, the International Maritime Organization (IMO) issued guidelines (MEPC.1/Circ.833) to reduce URN from commercial shipping. These were revised in 2023 (MEPC.1/Circ.906) and supplemented with additional guidance for Inuit Nunaat and the Arctic (MEPC.1/Circ.907).
While offering advice and best practices, the voluntary guidelines do not establish binding requirements, have been ineffective in achieving meaningful URN reductions to date, and MARPOL has yet to explicitly define URN as a form of pollution.
In 2024, the Sub-Committee on Ship Design and Construction (SDC) agreed on an Action Plan to further prevent and reduce URN from ships. The aim is to minimize the adverse effects of underwater noise on the marine environment, particularly on wildlife and Indigenous communities.
The Action Plan outlines several tasks to be carried out by Member States through relevant IMO organs, including:
Establishing an experience-building phase (EBP), during which Member States and international organizations are invited to share lessons learned and best practices emerging from implementation of the Revised Guidelines
Developing targets and policies for URN reduction
With the EBP underway, momentum is building toward compulsory URN regulations.
This study utilizes targeted interviews with experts actively engaged in URN-related work, alongside a review of available data and relevant case studies, to generate insights into how URN reductions can be achieved. Particular focus is placed on identifying key targets and policy recommendations at the IMO to advance underwater noise reduction by 2030 and beyond.
