It’s Time for IMO to Regulate Underwater Ship Noise

To protect ocean biodiversity, the International Maritime Organization must take action to require commercial ships to reduce underwater noise.



A significant milestone was reached in January, when countries convened at the International Maritime Organization (IMO) and agreed upon a revised set of Guidelines to reduce underwater noise from commercial shipping.

The revised Guidelines provide detailed approaches to build, retrofit, and operate quieter ships. The Guidelines also acknowledge that commercial shipping is a primary contributor of underwater noise, and that it is adversely affecting a wide range of marine life, as well as impacting coastal Indigenous communities who depend on such species for their food, livelihoods and cultures. 

While the revised Guidelines won’t be final until they are formally approved and adopted by Member States at a meeting scheduled for July 2023, the agreement demonstrates that countries across the planet recognize the urgent need to reduce underwater noise from shipping.

But there remains much work to be done. Next up, IMO member countries have committed to identify a proposed program of action to further prevent and reduction underwater noise from shipping. 

Over the next year a sub-group of delegations from various countries and organizations with IMO consultative status will meet to debate what measures should be included in a proposed program of action. (The proposed program of action will be comprised of recommendations that will be sent to the full IMO for consideration in 2024.) NRDC will be engaging in these sub-group discussions and will advocate that the recommendations include proposals for new policies that compel ships to limit underwater noise emissions.

First, a bit of background. The IMO adopted its original Guidelines to reduce ship noise in 2014, almost 10 years ago. Unfortunately, those Guidelines have been largely ignored by the shipping industry. In 2019, Environics Research and the World Maritime University conducted a survey that revealed that while the industry was aware of the Guidelines, it was not using them to make changes to ship design and operation because it was not mandatory for them to do so. The voluntary nature of the Guidelines has long been the biggest impediment to their uptake and implementation.

This is not a surprise, really. The shipping industry must prioritize meeting regulatory requirements – they are beholden by law to do so. Those changes that are “nice to do” will never rise to the top. 

Now that the Guidelines have been updated, it is time for the IMO to require ships to take the types of action outlined in the Guidelines to reduce underwater noise. By setting ship-based limits on underwater noise pollution and requiring ships to meet or stay below such limits, the IMO could make significant strides toward quieting the 100,000 ship (and growing) international commercial shipping fleet. 

Some countries are already moving to regulate ship noise in domestic waters. In 2022, the European Union adopted thresholds for underwater noise that cannot be exceeded. EU Member States must now develop regulations for shipping (and other sectors) that will ensure compliance with these thresholds. Additionally, Canada has identified ship-based noise limits, and is currently evaluating how those limits might be implemented, with recommendations from an expert policy group expected this fall. And as I wrote about here, the U.S. is developing new programs to support the deployment of quiet vessel technologies.

While this momentum is positive, a patchwork of regulations around the globe creates difficulties for industry. A global regulation issued by the IMO would level the playing field, creating a singular set of expectations for industry to follow. A global regulation would also ensure that countries that care about reducing the impact of underwater noise pollution on sensitive marine life won’t be penalized for regulating commercial shipping noise in their waters. 

Additionally, a global regulation that sets limits on underwater noise from shipping will facilitate the intentional design of ships that are both carbon free and quiet. As I wrote here, society has a unique window of opportunity – the next five to ten years – to design the zero-emission ships of the future. It would be the ultimate travesty if the carbon-free ships plying the globe in 2050 continue to pollute the ocean with underwater noise. It is better to address carbon pollution and underwater noise pollution in tandem, and a global regulation on underwater noise will put in on par with new regulations to reduce greenhouse gas emissions that came on-line this year.

The stakes couldn’t be higher. Underwater noise from shipping has been doubling roughly each decade since 1950, and a recent study has confirmed that this trend is continuing. It is time for the IMO to move beyond voluntary Guidelines and to adopt mandatory measures that are capable of reducing underwater noise and restoring healthy ocean soundscapes.

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