Less ice, more shipping noise to affect Arctic marine life

The newly released Arctic Report Card 2022 from the National Oceanic and Atmospheric Administration (NOAA) in the United States includes details that, unfortunately, come as no surprise. Temperatures continue to rise and sea ice is melting. But with those changes comes one that isn’t as obvious: an increase in noise from shipping traffic, with the potential to affect marine life.

“The increasing number of ships over time in all national and international maritime jurisdictions north of the Arctic Circle raises diverse questions about relative ship-traffic changes,” said experts from the Science Diplomacy Center who authored the shipping section of the report card.

Since 2009, when satellites began tracking Arctic maritime routes, ship traffic has risen as the barrier of sea ice has declined. That was especially true of vessels coming from the Pacific Ocean through the Bering Strait to the Beaufort Sea. Experts monitor Arctic shipping for a host of reasons, including national security concerns and the evolving geopolitical competition over the economic benefits of maritime access.

There are arguments for why Arctic shipping might offer carbon emissions benefits by reducing the length of maritime routes. But ship strikes and underwater noise affect marine mammals and birds, with the potential to disrupt delicate ecosystems already facing pressure from climate change.

Dr. Kate Stafford of the Marine Mammal Institute at Oregon State University is an expert on how marine shipping may affect the underwater biophony, or soundscape, of the Arctic— and transform it as anthrophony, the ecosystem of sound that’s introduced by humans.

“Marine animals, including marine mammals, rely on sound more than other senses to navigate, to find food, for reproductive displays, and to communicate over relatively long distances,” explains Stafford in a 2021 paper. “In the past few years, acoustic data have been documenting changes in the seasonal distribution of Arctic marine mammals.” 

The ships themselves aren’t the only source of disruptive sound. Oil and gas exploration, as well as drilling itself, also affect underwater sound in the Arctic. But the low-frequency sound of ships can travel for hundreds of kilometers, and some routes have seen a 44% increase in traffic (as measured between 2013 and 2019). Cargo vessels and fishing boats are common but in 2021, four liquid natural gas tankers crossed the Northern Sea Route without the need for icebreakers.

How that affects marine life isn’t fully known, though research demonstrates interference with communication and navigation signals and increased stress. It also depends on the precise sound: low-frequency noise is more of a problem for bowhead whales, while mid-frequency sound has a greater impact on walrus and ice seals. 

“Because extensive commercial shipping in the Arctic is a relatively new phenomenon, Arctic species may have a lower tolerance of, and react more strongly to, such noise,” said Stafford, citing data from the Protection of the Arctic Marine Environment (PAME) group of the Arctic Council.

Of course, Arctic shipping doesn’t only impact marine life. Indigenous communities at home on Arctic islands and coastlines rely on marine ecosystems for life and livelihood, and are the most vulnerable to shipping traffic increases facilitated by the melting ice.

The NOAA report card calls for improved understanding of these impacts across “a continuum of urgencies” in order to build resilience as the Arctic environment changes.