The Royal New Zealand Navy recently launched its own journal ^[1], which aims to build the service’s professionalism and ‘engage and exchange views with all those who have an interest in naval and maritime affairs’. The most eye-catching contribution in the inaugural edition is by the RNZN’s chief naval architect, Chris Howard, with the provocative title ‘Toward a zero carbon navy’. It’s a fascinating read.

In November 2019, New Zealand’s parliament passed the Climate Change Response (Zero Carbon) Amendment Act ^[2]. Net emissions of all greenhouse gases, except methane, are to be reduced to zero by 2050. The act requires all parts of society to examine their emissions levels and reduce them wherever possible and practicable.

There aren’t any net-zero-carbon navies. But the RNZN is the only navy paying into an emissions trading scheme. It pays New Zealand’s treasury a capped price of NZ$25 per tonne of carbon dioxide equivalent and receives a substantial rebate for fuel assessed as burned overseas on task. That’s because those emissions are deemed international and so fall outside the scope of the national scheme.

Howard argues that the RNZN should declare an intent to work towards becoming the world’s first zero-carbon navy and seek operational and technological efficiencies in its fleet.

Interestingly, Howard doesn’t support targets for emissions reductions, noting that ‘the security implications flowing from climate change are likely to increase the required operational tempo’. Rather, he suggests that the RNZN support alternative green fuel technologies to reduce the carbon intensity of operations.

Defence ship acquisition policies and maritime regulations should, Howard argues, be developed to encourage technological improvements. He suggests that the RNZN partner with others in the maritime domain, and with its sister services, which are also seeking to reduce their carbon footprints.

While not sceptical, Howard is realistic about the difficulties of reducing the carbon footprints of navies: ‘[F]or the next few decades, it seems probable that most naval ships worldwide will continue to rely on diesel fuel.’ But he suggests that the RNZN could, for example, showcase a green-ship technological commitment by acquiring an all-electric vessel as a tender or future VIP barge. (New Zealand’s first all-electric passenger ferry is currently being constructed ^[3] locally.) Autonomous maritime vessels such as solar-powered wave gliders could also help monitor New Zealand’s large offshore zone.

Howard points out that New Zealand’s future Southern Ocean patrol vessel is expected to feature ^[4] clean and efficient design practices and support climate change science in Antarctica. He suggests that the vessel aim for part usage of methanol as fuel, noting that any spill would be almost non-toxic. New Zealand has one of the largest methanol production plants ^[5] in the world.

Howard concludes, however, that over the next few decades, the full net-zero-carbon goal can only be achieved by purchasing carbon offsets through the NZ emissions trading scheme to ‘make up the deficit between the design and operational efficiencies that can be generated, and the Navy’s total carbon footprint’. He also talks about ‘blue’ carbon sequestration ^[6] in New Zealand’s exclusive economic zone and suggests that the RNZN use its international rebates under the scheme to invest in blue carbon research.

Climate change is expected to result in an increase the frequency and intensity of extreme weather events, which will affect the missions of navies. That’s because navies play a key role in disaster relief operations, particularly when airports have been rendered unusable. Think of the Royal Australian Navy’s role in bushfire relief ^[7] in 2019–20.

Navies may be the most effective first responders in such circumstances, with their ability to bring in important capabilities, including medical amenities, command and communications facilities and heavy machinery. (Paradoxically, an increasing use of navies in climate disaster missions would, without a major technological breakthrough, increase carbon emissions.)

It’s not surprising, then, that navies have in many ways taken the lead in setting up cooperative arrangements for disaster responses in the Indo-Pacific.

Reflecting the frequency of natural disasters, the Indian Ocean Naval Symposium ^[8] has highlighted disaster response as a priority area for cooperation among regional navies, helping build confidence and trust among those who might otherwise see each other as adversaries.

At sea, more cyclones and rough seas may affect mobility. Naval engagement in law enforcement will increase to deal with people flows as well as more illegal, unreported and unregulated fishing and other changes to the marine environment caused by increased ocean acidification.

Most naval infrastructure was built on the assumption of a stable climate with a predictable variability. But many naval facilities are built in low-lying areas ^[9] exposed to storm surges and sea-level rise. Naval maintenance schedules could be disrupted if facilities are damaged by storms.

Understanding the ocean environment is vital to naval operations. The data routinely collected by naval vessels, including submarines, can be used to monitor ^[10] the impact of climate change on ocean conditions.

Climate change will alter the physical environment in which navies deploy. Naval planners will need the best climate science to inform their plans.

Navies can’t prevent climate change and it will be decades before they become carbon neutral, if they ever do. Many ships need steel, but steel production contributes significantly ^[11] to climate change. Still, navies should prepare for climate change and lower their carbon emissions.

In a memorandum ^[12] issued to all Department of Defense employees, US Secretary of Defense Lloyd Austin states that to tackle the climate crisis the department will reduce its carbon footprint and ‘seek to lead the way for alternative climate-considered approaches for the country’. As part of this effort, the department is establishing a working group ^[13] on climate change.

When it comes to the environment, the declared efforts by the RAN ^[14] don’t mention climate change. And we’ve heard little about progress in the RAN’s agreement with the US Navy ^[15] to explore the use of alternative fuels.

Prime Minister Scott Morrison has said ^[16] Australia should get to net-zero emissions ‘as soon as possible’ and preferably by 2050.

The RAN should be a leading example in meeting, and possibly exceeding, requirements for reducing greenhouse gas emissions. The challenge will be for the RAN to achieve this without curtailing its operations.