They'll be Too Loud
The AUKUS pact promises to provide Australia with the first of its nuclear-powered submarines (SSNs) in the 2030s. But how will those boats, and the AUKUS SSNs to be delivered in the 2040s, fare in oceans whose soundscapes have been altered by ocean acidification and climate change?
A new study suggests that over the coming decades, soundwaves will travel further through a warmer, chemically different, less dense ocean—and it will be noisier underwater than ever.
Australia learned long ago that acquiring submarines is complex and always takes longer than expected. This was certainly the case with the Oberon class that Australia purchased from Britain in the 1960s—eight were ordered but only six delivered. And it held true for the Collins class that followed, which had problems that took almost 20 years to remediate.
Lengthy submarine design and delivery schedules create opportunities for adversaries to capitalise on fast-moving disruptive technologies such as artificial intelligence, quantum computing and autonomous systems. These technologies will change how underwater operations are conducted in ways that are difficult to predict and account for.
However, it is possible to predict with some confidence the ways in which the acoustic environment will change over the coming decades—and a simulator does just that. research suggests that as the oceans become warmer and their chemical make-up changes, sound will travel further due to reduced transmission loss.
By 2100, ultrasonic sonar transmissions in the 30 kilohertz range (a frequency that might be used for mine hunting) will travel between 40% and 87% further than they do today, and sonar transmissions in the 10 kilohertz range (a frequency appropriate for hydrographic mapping) will travel between 15% and 25% further.
The effect will vary depending on latitude: colder polar oceans will experience more extreme variations than warmer coastal waters.
With sound traveling further, undersea stealth platforms such as submarines will find it more difficult to hide in the open ocean. But they may also find it easier to hide in coastal waters, as the ocean becomes noisier.
Experts have modelled the effects of our changing oceans over time by bringing together predictions from the UN Intergovernmental Panel on Climate Change’s representative concentration pathway 8.5 climate model with data from ocean-going Argo data-collection robots that agencies such as the CSIRO use to monitor ocean parameters. This data was fed into a custom-built simulator, which generates a digital twin of the ocean to explore what these changes might look like.
The impact of changing hydroacoustics is far-reaching, extending to military, commercial and scientific applications. It will have significant effects on underwater technologies that rely on sound, such as active and passive sonar, hydrophones, echo sounders, fish finders and sub-seafloor profiling devices.
Research findings suggest that the changed environment will have positives and negatives for submarines. Thermal layers are likely to have a greater density differential with the cooler water below them compared to today. This means that submarines will be harder to detect when such a layer is present. However, because sound will travel further, when there’s no thermal layer they may be easier to detect.
Even as it potentially becomes much more difficult to hide in the open ocean, increased noise across the full acoustic spectrum, as well as increasing sound intensity overall, will likely make hiding in coastal shallows, littoral waters and archipelagos much easier.
The time involved in taking a submarine from concept to operations means that the Australian Defence Force needs to start planning for a changing environment now. Naval architects will need to consider material choices for both anechoic plating and hull construction, while marine engineers will need to consider improved dampening for the mechanical components that generate noise. Electrical engineers will need to begin designing next-generation sonars, sensors, processors and filtering techniques to improve their ability to detect hostiles amid very loud ambient noise.
Future submarines will almost certainly use embedded artificial intelligence and machine learning to process acoustic signal intelligence. The developers of these systems will need to take future acoustic conditions into account when assembling training datasets, or they may train an AI with a keen ear for today that won’t be suitable for tomorrow.
Picture this scenario. An Australian frigate is on patrol in the Coral Sea around 100 kilometres off the north Queensland coast when it receives intelligence that an enemy submarine is in the area. It pings the warm waters at 3,500 hertz with its sonar. Under conditions recorded in October 2023 by an Argo robot in the area, that sonar ping would be audible to a range of 28.5 kilometres. In 2100, the same sonar ping, in the same location, would be audible at 37.5 kilometres. When considering the circular area covered by the sonar in this scenario, that’s an increase of about 73%, from 637 square kilometres scanned in 2023 to 1,104 square kilometres in 2100.
More research is needed on this subject to understand the changing world that awaits us under the sea—especially considering the recent joint statement of AUKUS defence ministers about the important work to come in areas such as trilateral anti-submarine warfare and undersea vehicle launch and recovery.
The pilot study conducted by Rhys Kissell - a systems engineer at defence engineering firm ADROITA - is a significant step towards understanding the effects of climate change on ocean hydroacoustics, but it has its limitations. We need more data, and future work should look to expand the dataset and modify the 2100 model to better align with today’s most advanced oceanographic models. Changes to the sea surface will also need to be factored in. The information we gain may make a significant difference to how we approach future warfare in the Indo-Pacific and will be an important part of maintaining a maritime capability edge. It may also provide insights that help Australia address two existential problems—climate change and our geostrategic circumstances.
Understaffed and Undeliverable
As the Australian government welcomes US approval of an interim submarine sale ahead of a new British design, another new report raises questions about Canberra’s ability to deliver AUKUS on time and on budget.
Passed last week, the 2024 National Defense Authorization Act (NDAA) greenlit the sale of Virginia-class nuclear-powered submarines to Australia, required to fill a capability gap in between the phase out of its older Collins-class fleet and the delivery of the new AUKUS subs. It will make Australia the first non-nuclear weapons state to possess such technology which will no doubt increase a wider tendency towards nuclear proliferation.
The NDAA also included permission for the Virginias to be repaired at Australian shipyards, training for Australian contractors in the US, as well as technology shares and exemptions for both Australia and the UK from the US export licensing regime. All are aspects required to help Australia make its own UK-designed fleet under the AUKUS pact. The same design will also replace the British Royal Navy’s Astute fleet in the 2040s.
However, a report published by the University of Sydney’s United States Studies Centre earlier this month raises questions about Australia’s ability to make and deliver its submarines on time. AUKUS inflection point: Building the ecosystem for workforce development, draws on the problems experienced by US and Britain in building their respective Virginia and Astute fleets despite their experience in shipbuilding and nuclear technology.
Among them include the plague of delays and cost overruns faced by manufacturer BAE Systems during its 17-year programme to build the Astutes. These are blamed on a major drop in the workforce at the Barrow shipyard from 13,000 to 3,000 between the end of the building of Britain’s Vanguard-class and the start of the Astute programme. A reduction in Ministry of Defence staff at Barrow also led to less government oversight, compounding problems further. According to a 2022 report by the Labour Party on overspending in the MoD, delivery of boats 4-7 in the Astute fleet alone came in £1 billion over budget.
Australia is expected to need a 20,000-strong workforce to build and maintain its AUKUS fleet – with many more working in its supply chain. But with unemployment at a 50-year low, it could face problems in finding the staff to deliver the programme as non-military sectors compete for the same workers.
Popular support is also necessary for the programme to work. However, the report highlights that the Australian public is more than ambivalent about the AUKUS pact. Its remit has already extended beyond submarines to include deep space radar technology and hypersonic missile development. A poll conducted by The Guardian in March 2023 found that only a quarter of Australians were happy to pay AUS$368 billion for its AUKUS fleet. It also found that only 40 percent thought the pact would make them safer, down 4 percent from November 2022.
Campaign for Nuclear Disarmament General Secretary Kate Hudson said:
“From aircraft carriers to nuclear submarines, major overspending at the taxpayer’s expense has become an all-too-familiar feature of military procurement. Announced in the final months of the previous Australian government and quickly expanded to include a raft of new military technologies, everything is stacking up to suggest that the AUKUS submarine programme will be the same. There is considerable opposition to AUKUS in Australia and it is likely to grow further when the price tag inevitably rises. Driving a new arms race in the Indo-Pacific will make Australia less secure and increase tension in the region. And building the subs would draw in scarce and valuable resources that could be better used in sectors like the green economy. It’s time for Australia to pull the plug on AUKUS.”
New Zealand NIMBYs Prevail
New Zealand has stayed on the non-nuclear course, however. New Zealand's prime minister has flagged the prospect of joining an expanded AUKUS defence pact but laid out his country's "non-negotiable" condition for involvement.
In Australia on his first overseas trip since winning New Zealand's October election, Chris Luxon also welcomed Australia's decision to fast-track citizenship pathways for the roughly 670,000 New Zealanders living in Australia.
Speaking at a press conference alongside Prime Minister Anthony Albanese on Wednesday, 20 December 2023, Luxon framed the AUKUS pact - currently signed between Australia, the US, and the UK - as key to maintaining peace in an increasingly volatile Indo-Pacific. "We know we're facing a more challenging and complex world ... [and the] defence relationship we have with our only ally, Australia, is very foundational for New Zealand," he said.
"So New Zealand is committed to doing our share of the heavy lifting in the alliance."
Under AUKUS, Australia is set to obtain a fleet of nuclear-powered submarines from the US after controversially scrapping a multi-billion dollar deal with French company Naval Group. Obtaining the fleet is known as pillar one of the AUKUS arrangement.
"We will always have our nuclear-free position, that's not non-negotiable for us in New Zealand," Luxon said.
"But we have our navies that work together and we want to see more interoperability, frankly, between our respective defence forces. From my point of view, we're interested in exploring pillar two (jointly-developed advanced military technologies), particularly in AUKUS and the new technologies and the opportunities that may mean for New Zealand to participate."
The announcement of the AUKUS pact angered the Chinese government, and Luxon's predecessor Chris Hipkins described China as an "incredibly important partner" while stressing there would be no watering down of his country's nuclear stance.
Hipkins, who was in office for less than a year after replacing Jacinda Ardern, also made Australia his first international stop.
But with Far North Queensland experiencing major flooding, Albanese signalled that New Zealand's involvement in the pact would likely be based on deeper military cooperation.
"That has practical effect as well. It's about efficiency ... Our defence forces ... support each other at time of need, of natural disasters. That's just one area whereby increased cooperation could benefit both of our nations," Albanese said.
Anti-nuclear policy has been a central principle of New Zealand politics for decades.
It declared itself a nuclear-free zone in the late 1980s, prompting the US to revise its status down from "ally" to "friend". Australia remains New Zealand's only formal ally.
While some minor parties in New Zealand have called for its anti-nuclear stance to be repealed, both major parties and strong public sentiment are opposed to the idea.
That is a sticking point for full engagement with AUKUS which, apart from being signed by two nuclear-armed powers, also includes the development of nuclear-powered submarines for Australia.
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