Changing Soundscape of the Arctic Ocean

Rising activity in Arctic waters

The Arctic Ocean’s underwater acoustic properties differ from non-polar waters. Sea ice acts as a shield and diffuser of underwater sound. Cold water and changing salinity gradients also affect sound propagation underwater. Further, due to properties in the water column, sound can travel longer distances at shallower depths than it can in the world’s other oceans. This means the addition of even a small amount of human activity can have major impacts to the underwater soundscape.

Yet, human activity is on the rise. Shipping in the Arctic has increased 37 percent over the last 11 years, according to the Arctic Council’s Protection of the Arctic Marine Environment Working Group (PAME). Other activities like oil and gas exploration (through seismic surveying in particular), as well as port construction also introduce noise into the water, negatively affecting marine ecosystems as well as Indigenous and local ways of life.

For many years, there was a major gap in our knowledge about human-caused underwater noise in the Arctic and the impact it may have. PAME set out to fill this critical knowledge gap, first by developing a State of Knowledge report in 2019, then – for the first time – mapping underwater noise from shipping across the Arctic Ocean, with results published in 2021. Now, PAME is releasing a new report that includes modeling future scenarios of what the Arctic Ocean could sound like in 2030 based on factors likely to influence shipping trends.

How underwater noise impacts animals and ecosystems

As an Observer to the Arctic Council, the WWF Global Arctic Programme has co-led the Underwater Noise in the Arctic projects. Dr. Lancaster, with her background in research and conservation of species, has been closely involved in PAME’s latest report. She explains the big impact that underwater noise can have on Arctic species.

“We know that marine life in the Arctic Ocean is quite naive to underwater noise because they’ve been naturally shielded from sources of human-made noise,” said Dr. Lancaster.

She explains that extremely loud noises can damage animals’ ear drums, or even lead them to strand on beaches, which can cause death. Shipping noise, however, is different.

“Shipping is most likely causing disturbance to animals, leading them to stop feeding or to leave an area,” said Dr. Lancaster. “For example, narwhal are extremely sensitive to underwater noise and can change their entire behavioral pattern. If a ship navigates through their natural habitat, it can cause them to leave and not return for several days or longer if there’s repeated activity. The sound can cause narwhal to reduce or completely stop eating, while they also use up more energy to flee.”

Dr. Lancaster shared that there have been observations of beluga whales fleeing in response to an ice breaking ship from 30 to 50 kilometers away. She explained that they form groups and once they’ve fled, they won’t come back to the area for several days. Walrus have been observed to change their behavior, increasing their diving and moving away from the source.

Underwater noise doesn’t impact species in isolation, it impacts the entire ecosystem. If one species changes behavior because of noise disruption, that can have ripple effects on the food web. A growing body of knowledge also tells us that underwater noise has impacts on many marine species, from mussels to fish, right up to whales. Dr. Lancaster also points out that noise pollution is just one disruption species need to contend with.

“We already have animals trying to cope with transformation of their habitats and changes in their food sources due to climate change. A number of these species are dependent on sea ice for example, so they’re experiencing massive changes all around.” said Dr. Lancaster. “We’re concerned the addition of yet another pressure due to underwater noise is something that’s unnecessary in the Arctic.”

Healthy populations of marine mammals, fish and other species are critical for the livelihoods, food security and cultures of many Indigenous Peoples.

“A lot of these species that we know to be particularly affected by underwater noise are also species that are heavily relied upon by many coastal Indigenous Peoples. This element can’t be understated. We need a healthy ocean,” stated Dr. Lancaster.

Mapping a new ambient soundscape

In 2021, PAME used information from its Arctic Ship Traffic Data (ASTD) and the expertise of bio acousticians to create the first ever map of underwater noise from shipping across the entire Arctic Ocean. The results revealed a soundscape that had already undergone dramatic changes.

PAME found that some places in the Arctic Ocean experienced a doubling in noise levels from 2013 to 2019.

"For comparison, the North Pacific Ocean took between 30 and 40 years to reach the same magnitude of noise increase as it took in just six years in the Arctic,” said Dr. Lancaster.

During the winter months, underwater noise from shipping was concentrated in areas with more open water such as the Barents and Kara Seas, the southern Bering Sea and along the Greenland coast of Baffin Bay. In the summer months, noise levels were higher and spread out farther, into the Canadian Archipelago, the Chukchi and Beaufort Seas and even the Central Arctic Ocean.

Dr. Lancaster points out that the reason for such a dramatic increase in noise in the Arctic is because the baseline is so low.

“Sometimes people will look at these data and wonder why we are worrying about underwater noise in the Arctic when there’s so much more shipping in the Baltic or North Seas, for example. But the point is, the Arctic is a special case. Sound travels differently in the Arctic Ocean compared to other oceans. Baseline levels are low, and so even a small input of ships can have a large effect on the underwater soundscape. If you imagine the animals living in these environments, they're going from having a relatively quiet background to all of a sudden a very loud environment they then have to contend with.”

Testing solutions to mitigate underwater noise

After PAME was able to map the Arctic’s underwater soundscape, the project entered a new phase: figuring out what the Arctic could sound like in the future and exploring how a variety of shipping management measures could affect underwater noise in three sub-regions of interest: Baffin Bay, the Barents Sea and the Chukchi Sea. The sub-regions were chosen as they are known to have a high overlap between important marine mammal habitats and ship traffic.

The results of the latest project phase show that, with no further policy action, by 2030, underwater noise from shipping will increase across the Arctic Ocean as a result of more ship traffic and reductions in sea ice extent and thickness. The modelling predicts that increases in noise levels will not be uniform and can range from a doubling to a ten-fold increase, even in areas with relatively low shipping currently, such as Baffin Bay and the Chukchi sea.

One suggested measure to limit underwater noise is to reduce ship speeds in the Arctic to 10 knots. However, in the few areas examined, most ships were found not to be travelling above 10 knots in the first place, suggesting that imposing speed reduction measures may not have a large impact in parts of the Arctic where ships are already travelling slowly.

Another potential measure to address underwater noise is to re-route ships around areas of biological importance. However, this measure requires considering an important trade off: moving ships from one location to another also shifts the associated underwater noise. Those consequences should be included in planning.

“The Ocean doesn’t have physical barriers, so even designating a marine protected area with limited shipping might not stop noise from entering. One of the project’s recommendations is that spatial measures to manage shipping around important habitats should include buffer zones to make sure that underwater noise from ships outside the area won’t permeate in.”

Technical solutions that can help reduce underwater noise include retrofitting vessels with a different, quieter propeller and regular hull cleaning.

Results from PAME’s latest report on underwater noise in the Arctic, including future scenario mapping, will be shared with the International Maritime Organization (IMO), the United Nations agency responsible for the safe shipping and prevention of pollution by ships.

The IMO, who is also an Observer to the Arctic Council, does have global underwater noise reduction guidelines for optional uptake. However, according to Dr. Lancaster, the unique conditions in the Arctic call for special guidance to be put in place in the region.

“WWF as an Observer to the Arctic Council has been contributing to PAME’s underwater noise work for about nine years now,” said Dr. Lancaster. “We’re happy that the Arctic Council continues to work on the issue, as this is an important area of focus for WWF as well. We at WWF continue to advocate for measures to reduce the impacts of underwater noise from shipping, particularly in the Arctic."

PAME’s efforts to investigate scenarios for noise levels are important in identifying the most effective management measures. By modeling future scenarios, PAME’s recommendations can be acted upon now before underwater noise becomes too much of a problem in the future.

“With the Arctic Ocean, we have an opportunity that we don't have in the rest of the world's oceans anymore,” said Dr. Lancaster. “This really is the last ocean that is relatively unpolluted by underwater noise. Instead of degrading nature and then trying to figure out how we can reverse that trend, we have an opportunity to actually put measures in place before more harm is done."

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This article was authored by:
Jessica Cook, Arctic Council Secretariat