The expected sonic transformation of the Arctic Ocean under Climate Change

Giacomo Giorli –

NATO STO CMRE, Viale S. Bartolomeo, 400, La, Spezia, 19126, Italy

Aniello Russo
La Spezia, Italy

Sandro Carniel
La Spezia, Italy

Popular version of 2pAO2 – Noise levels in a changing Arctic Ocean and its implications for security
Presented at the 185th ASA Meeting
Read the abstract at

Please keep in mind that the research described in this Lay Language Paper may not have yet been peer reviewed.

Global warming is rapidly driving a substantial transformation of the oceanographic characteristic of the Arctic Ocean and its cryosphere. The Arctic region is in fact warming up much faster than the rest of the planet, and recent studies and reports have highlighted its major consequences. In much of the ice-free Arctic Ocean, the mean sea surface temperature continued its warming trend observed since 1982 and ice sheets in Greenland receded for the 25th consecutive year. According to NASA reports, this year the annual sea-ice minimum extent was the sixth lowest on record. Such an observation implies a significant sea ice retreat and reduction of ice longevity, which will most likely turn the future Arctic in a giant Marginal Ice Zone. Storm and rain patterns are also changing, having Arctic precipitations significantly increased since the 1950s across all seasons. Moreover, increased heat fluxes injected by  warmer Atlantic waters  are preventing the formation of new ice, as well as reducing the thickness and longevity of multi-year ice. The resulting atmosphere- ocean interactions under these new forcing create more turbulent mixing (heat) between the deep Atlantic waters and the upper Arctic Ocean, hence a positive feedback mechanism usually referred to as “Atlantification”, that is, a climatic shift driving the Arctic Ocean towards new and different oceanographic characteristics. Moreover, an ice-free Arctic will open up new possibilities for deep-sea resources extraction, new commercial and military routes and activities. All these environmental modifications are already affecting the Arctic Ocean underwater soundscape. An example is provided by the underwater noise at low frequencies, expected to increase due to the openings of new routes for maritime shipping resulting from nearly ice-free seas (Figure 1). In addition, the more frequent storms and intense precipitation would affect the sea state generating bubbles and spray associated with breaking waves, hence increasing the underwater noise. Additional contributions are due to changes affecting marine life, marine food industries and coastal economies.

Figure 1: Main maritime routes across the Arctic Ocean with minimum sea ice extension. Source: US Navy Arctic Roadmap 2014-2030.

In the lights of this ongoing transformation of the Arctic, CMRE conducted a series of studies and sea-trials (funded by the NATO Allied Command Transformation) of the new Arctic oceanographic conditions and ambient noise. In 2021 and 2022, a series of moorings equipped with passive acoustic recorders and oceanographic sensors were deployed in the region of Fram Strait. In 2023, with the additional support of the NATO Office of the Chief Scientist, CMRE started a long-term scientific endeavor to address how climate change might affect the Alliance’s security in the maritime domain. In June-July 2023, CMRE deployed three deep moorings for monitoring the acoustic-oceanographic conditions in the long term.

Results contribute to create a long-term database of acoustic measurements and to understanding how sounds from different sources (biological, man-made and natural) will change in the next decade.