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How underwater noise can be reduced

12 May 2023

Underwater noise is a growing environmental problem and is considered a pollution by the UN and the EU. Despite that, there is a lack of regulations and effective measures to reduce noise. A new report from IVL and the Swedish Maritime Administration presents proposals for how the problem can be handled.

In recent years, scientists have seriously begun to understand that marine life is disturbed by the noise that a growing shipping industry makes in the oceans. There’s been reports have on how fish and whales can no longer communicate with each other, locate partners, or in the worst case scenario – die on the spot. But exactly when such effects occur is largely still unknown.

“We know a lot about how underwater noise is created and spread, but far too little about how it affects the environment. What was most surprising to us, however, was how little is known about how to reduce the noise with various technical and operational measures. There have simply not been any financial or regulatory driving forces to develop such measures”, says Torbjörn Johansson, project manager at the IVL Swedish Environmental Institute.

A large ship can be heard ten kilometers away, sometimes even further away. Water conducts sound better than air, but despite that, there is currently no regulation on how much noise each individual ship is allowed to make. However, the UN's international maritime agency IMO is in the process of updating its voluntary guidelines on ship noise and within a few years EU legislation on permissible levels is expected to enter into force.

Motivated by environmental concerns and coming EU legislation, the reseachers vision is that Sweden should become the first country to implement national incentives for underwater noise mitigation.

“It is possible to reward speed reductions or technical measures for noise reduction, but it has not been determined how effective it would be. Ship design for quiet operation is established for military and research vessels, but not for merchant ships. At the same time, there are uncertainties in how carbon dioxide emissions are affected by noise reduction measures”, says Torbjörn Johansson.

In total, the report Underwater noise from fairways presents six ways of designing financial incentives are presented:

Predict the radiated noise from a vessel based on its characteristics

Reward speed reductions

Reward technical measures for noise mitigation

Use silent notations

Perform a noise inquiry

Establish Establishing bespoke measurement stations.

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