Militaries can’t ignore climate change – it could cripple their tech
Armies, air forces and navies are some of the world's biggets emitters but global warming is now forcing them to reengineer how they do things.
It is the year 2085. The US and China are on the brink of war. As the crisis deepens, a Chinese submarine positions itself dangerously close to America. The spy sub, shrouded in the waters of the North Atlantic, is there to snoop on US military activity.
Nearby are sonar-based listening systems designed to detect the whisper-like noises made by encroaching enemy vessels like this one. But the listening systems don’t work as well as they used to.
A young US naval officer on high alert only picks up the Chinese boat when it is a few kilometres away from one of the detectors. He panics, and misidentifies the sub as a nuclear-armed attack vessel. His hawkish commander, without hesitation, picks up a red telephone and barks a single word: “Launch”.
It might not immediately be obvious but climate change has the power to drastically affect military technology. From shutting down ship engines to reducing the payload that transporter planes are able to carry, even the world’s best-armed organisations are far from immune to climate change. And the people in charge are starting to notice.
That harrowing vignette of a submarine misidentification sparking conflict between two of the world’s most powerful nations is not a prediction or a war-gamed scenario – but it is what came to my mind recently when I spoke to Andrea Gilli of the University of St Andrews.
Gilli, who is also an advisor to the Italian Ministry of Defence, was the lead author on a paper published earlier this year that explored how climate change could affect submarine detection.
Silent and deadly
The North Atlantic is expected to become much warmer and saltier than it was at the beginning of the century. Sound won’t travel through these waters like it does today, and that in turn could constrain the capabilities of aging submarine detection tech.
“This is really the nightmare scenario,” says Gilli, as we discuss the possibility that weakened sonar systems could play a role in the escalation of some future nuclear crisis.
Exactly how temperature and salinity will affect sound waves depends on which part of the ocean we’re talking about. For example, under some conditions sound waves near the surface might move faster, which means they would naturally refract downwards. This could prevent the sound waves from reaching distant listening systems.
Gilli and his colleagues’ study modelled how climate impacts (under the RCP 8.5 scenario) could affect the transmission of sound through seawater in different locations, and at varying depths. One of the worst-hit places was the North Atlantic. Here, passive sonar systems – which listen for very quiet noises made by subs – on a submarine in the upper layers (0-500m depth) of the ocean would no longer be able to detect an enemy vessel at long distance.
The western Pacific Ocean, however, because of less drastic changes to temperature and salinity expected there, would be less severely affected, according to the study. In follow-up work that is yet to be published, the researchers say they have observed similar such effects when using the RCP 6.0 scenario in their model.
To avert submarine detection failures decades from now, militaries may invest in improvements to their sonar listening technology in the coming years, Gilli suggests.
A Nato report on climate risks published this summer cited Gilli and his colleagues’ study, among others. Separately, it also noted that warmer air makes helicopter engines work harder, which wastes fuel, and can even lower the maximum altitude at which these vehicles can hover.
“Based on data obtained from the US [Department of Defense] Military Standards and the operations manual of a medium-heavy naval helicopter, at air temperatures of 40C, maximum take-off weight at sea level is severely affected,” the report explained. Similarly, the maximum payload that a transporter aircraft can carry will also reduce as temperature and humidity increase.
The heat of battle
Giant warships are already having problems. At a 2022 parliamentary committee hearing in the UK, retired Lieutenant General Richard Nugee told MPs he was concerned about projections suggesting that the surface of the Persian Gulf could routinely reach between 38C and 40C within the next 15 years.
“Ship captains are saying to me that [their vessels’] engines have the potential to cut out when the surface sea temperature is what it is today, let alone 38C and 40C on really hot days in the Gulf,” he explained.
Air conditioning systems on massive US navy vessels are also struggling to cope with warmer seas, according to reports. And melting permafrost has caused cracks to appear in military runways in Alaska. At Nome Airport, a public-use airport in Alaska, engineers addressed such problems by burying steel supports in the ground.
Rising emissions could worsen global security, says Caroline Baxter, a senior adviser at the Council on Strategic Risks, a non-profit security policy institute.
The world’s armies, navies and air forces are themselves huge emitters. According to its own figures, the US military spews out the equivalent of 51 million metric tons of carbon dioxide every year – as much as the entire country of Sweden.
Globally, it is sometimes difficult to know how much military organisations are emitting because there is not always transparency on this point. One widely used statistic suggests that worldwide military activity is responsible for 5.5% of total greenhouse gas emissions.
The 2015 Paris Agreement stipulated that signatories did not have to report emissions from military activities – and that they could set their own targets in terms of reducing emissions, too.
Despite ongoing concerns over military emissions, there are some changes afoot. The US Department of Defense (DOD) will soon install solar panels on the roof of its headquarters, the Pentagon, for example. The panels are desirable partly because the DOD hopes they will ensure an electricity supply even in the event of a cyber-attack that scuppers the local electricity grid.
The impact that climate change is already having on military tech is important because it could, in the end, convince military leaders that they should make their operations more efficient.
A grumbling general might be receptive to the idea that he can boost his helicopters’ range by cutting the vehicles’ fuel consumption (and therefore emissions). This would be a relatively soft sell, suggests Baxter.
Threat avoidance
Whether this will be enough to drastically reduce military-related emissions is another question. And one that governments ought to consider, according to some observers.
Militaries are generally good at anticipating the dangers posed by their enemies, notes Baxter. “We throw millions and millions of dollars at the threat – to inoculate ourselves against something,” she says. “We’re not doing the same with climate change.”
Nearly 35 years ago, Carl Sagan gave a much-quoted speech about climate change at North Carolina State University. Among the many points he made was that, by 1990, the US had spent ten trillion dollars on the Cold War. Enough to buy everything in the US, except the land.
Governments and military leaders had eagerly spent this money, he noted, in order to protect the US against the possibility – the possibility – of the Russians invading. Preparing for dangerous contingencies, even remote ones, was classic military thinking, he said.
Sagan went on to ask, “Why doesn’t that same argument apply to global warming?”
Now, more than three decades later, the world’s militaries are increasingly unable to ignore the many climate risks that they, and their soldiers, now face.
Further reading on this week’s story
Check out Andrea Gilli and colleagues’ study in Texas National Security Review on how climate change could affect the capabilities of submarine-detecting equipment.
In 2022, the International Institute for Strategic Studies published a research paper on the concept of “green defence”, which includes lots of information on how militaries are attempting to decarbonise.
The Council on Strategic Risks has an interactive map that tracks military responses to climate-related disasters and hazards.
In a paper published last August, security studies researcher Richard Millburn argues that Nato could be taking a more active approach on climate change.
Various reports and studies detail the risk posed by extreme weather to military operations, besides the Nato piece linked to above. For another example, take a look at this paper by James Regens: “Extreme Weather Risk to Military Operations in a Changing Climate” (Paywall).