New research by ADROITA’s Systems Engineer, Rhys Kissell, forecasts a louder ocean over the coming decades with significant implications for submarine warfare.
ADROITA Systems Engineer Rhys Kissell privately conducted a pilot study into how climate change will affect the transmission of sound in the ocean over the next 80 years; concluding that the oceans of tomorrow will be much noisier than they are today with soundwaves travelling up to 87 percent further in some cases.
Rhys brought together temperature predictions from the Intergovernmental Panel on Climate Change with data from the United States’ National Oceanic Atmospheric Administration that itself drew from the 3,000 strong fleet of ocean-going Argo data-collection robots that the world’s oceanographic agencies use to track changes in the waters, and fed them into his own custom-built simulator to simulate the effect of higher temperatures, decreased salinity, and greater acidity on sound propagation and attenuation. The results were stark.
“My research found that ultrasonic sonar transmissions in the 30 kilohertz range will propagate between 40 to 87 percent further than they do today, while mid-frequency sonar transmissions in the 10 kilohertz range will propagate between 15 to 25 percent further,” Rhys said.
The research indicated that effects will differ based on oceanic characteristics: low-latitude oceans will undergo a substantial acoustic transformation compared to the present, while polar oceans will experience a more extreme transformation.
“This will have a pronounced impact on technology that relies on hydroacoustics such as active and passive sonar, hydrophones, echo sounders, fish finders, and sub-seafloor profiling devices,” Rhys said, “But the most significant consequence will be for the underwater stealth technologies that are essential for military operations. It will be a lot harder for them to remain undetected,” Rhys said.
There are other consequences of the changes in the way sound behaves in the ocean that bear consideration by today’s defence planners. While the ocean environment will be louder and underwater platforms like submarines will become more detectable, there will also be greater opportunities for platforms to hide among the ocean noise. This means that there will be a need for better sensors, and processors that can be upgraded over time to enhance their processing power to give them greater ability to filter out ambient noise. This will have a cumulative impact beyond submarines and will also affect undersea surveillance programs as well.
“The year 2100 may seem a long way off, and yet the time involved in taking a submarine from the concept stage to transition into service, and the extended service life that many of today’s classes of submarines are experiencing, means that the marine engineers who are designing submarines need to begin taking these things into account today,” Rhys said.
The paper calls for further research into the effects of climate change on hydroacoustics to guide the technological and policy response from government, and the ADF especially. It also contributes to the relatively small existing body of literature by providing a multi-faceted view of anticipated changes in oceanic hydroacoustics due to climate change. He aims to address the literature gap with this pilot study and acknowledges its limitations due to a small sample size and simulator constraints.
The research paper can be downloaded here.