Climate change will increase the risks of conflict, and will reshape the environments in which military action takes place. At the same time, militaries are often the biggest public sector contributor to carbon emissions. How can the defence sector decarbonise, and adapt to this new environment?

In just three years, from 2020-2023, the Sahel region saw eight coups in six countries—two in Burkina Faso in 2022, one each in Chad and Guinea in 2021, two in Mali in 2020 and 2021, one in Niger in 2023, and a coup and ongoing civil war in Sudan since 2021. The causes of each are different, and the fertile strip of land south of the Sahara has suffered multiple broad causes of instability. But it is also seeing some of the worst impacts of climate change, with more than three million people in 2023 facing food insecurity and tens of thousands suffering catastrophic levels of hunger. This can only increase instability. And, as more and more of the world sees climate change have real consequences, we should expect further insecurity.

“Climate change has a number of different effects for military forces around the world,” says David Clark, AtkinsRéalis Global Defence Lead and VP Aerospace & Defence, UK and Europe. “Climate change causes conflicts. Where food becomes scarcer and more difficult to grow, there will be mass movement of people. And that will cause challenges for governments around the world.”

Contributing to climate change

As well as having an impact on the causes of conflict, climate change will have an impact on how military operations are conducted, according to Richard Gutsell, programme director at AtkinsRéalis.

“There are key things to emphasise,” Gutsell explains. “The first is the tempo of those operations. So when it comes down to high stress situations, natural disasters, and conflicts over resources, will become more common with climate change. It’s the military forces that are called upon. So the tempo call on our forces is going to become more regular.

“And the situations in which they’re going to have to operate are going to become more challenging.”

Climate change will turn tundra into mud, and farms into deserts. It will reshape coastlines, and threaten our ability to live in many cities. This will cause conflict, and change how military operations are conducted. At the same time, militaries are themselves significant users of fossil fuels and must take steps to mitigate those impacts.

“Statistics are a great way to look at that,” says Gutsell. “The UK military emits 3.1 million tonnes of carbon a year—that’s about half of government emissions, and that doesn’t include overseas operations. It’s reasonable to assume that that’s quite a lot larger, globally. 

“The majority of that is equipment, and of that equipment, aviation fuel, probably tops the list. But just like the rest of society, the rest of commerce and business, it’s a case that there’s an awful lot of different categories of emissions that you’ve got to go after there. It’s your heating systems, it’s your commuting to get to work. It’s all of those different things, and you’ve got to go after all of them to have a true impact on carbon emissions, and then you’ll probably have some residual emissions that you’ve got to offset.”

Making an impact on climate change will require access to alternative fuel sources. 

“It’s not just about frontline operations,” says Gutsell. “They all depend on their supply chain and the resilience of that supply chain. And that’s a national endeavour, not just a military endeavour. So down the line, we need to see that resilience in order to sustain those operations.”

Opportunity for innovation

But despite all of this, militaries can play a positive role in the fight against climate change. 

“There’s a huge amount of opportunity in that space as well,” says Gutsell. “If you look at how nationally we’re transitioning and greening the grid, transitioning to e-vehicles and new heating systems, there is a national change programme. We’re on that journey, delivering new nuclear power stations, delivering more renewables. That has a resilient effect on the military. But they need to make sure that their supply chain for electricity and for everything else is resilient.”

A key challenge for any organisation is logistics, and this is even more so for the defence sector. As General Omar Bradley, the first chair of the US joint chiefs of staff noted, “Amateurs talk strategy, professionals talk logistics.” At first glance, it may look like the energy transition will present further logistical challenges. But, Clark points out, it may actually bring operational benefits.

“Many operations are just moving supplies around,” Clark explains. “There might be different solutions in those spaces for more electric vehicles, and more alternative energy. If you can do this with operational infrastructure, such as camps or forward bases, then you are actually removing the need to continually ferry fuel in and out. This is a great benefit. The  benefits of sustainable and environmentally friendly technologies have a military benefit as well”

“It’s not easy to get that diesel fuel in,” says Gutsell.  “In Afghanistan, a huge amount of effort was drawn away from the frontline operations—delivering the mission they’re out there for—to protect supply convoys: civilian drivers trucking in fuel for the planes and vehicles that were conducting the operations. That’s hugely vulnerable and contributes to the cost of the operation, both in money, and in lives and injuries. The chance to decouple from that supply chain and bring innovation in is really, really significant.”

New operational benefits

There’s a tendency to think that electric equipment is in some way less powerful than its diesel counterparts. But it can already make it easier for military professionals to maintain high tempo operations, and that advantage is likely to increase as R&D is focused on new electric vehicles.

“It’s not the case that decarbonized equipment will give you less of an impact, and less of an edge,” says Gutsell. “It’s that it gives you a different edge. Take electric cars, which are probably the area that’s had the most commercial investment. There’s been a huge amount of innovation in that space, that actually offers significant advantages over fossil fuel engines.

“It is easier to learn to drive an electric car, there’s less to do, they’re more reliable. That’s pretty key in the battlespace. They’re also faster to accelerate. Again, if you want to get somewhere quickly or get away from somewhere quickly, [it is much better] to be able to jump on and go, as opposed to starting the engine and changing gears.” 

But we have a well-established global system for extracting and transporting fossil fuels. For the defence sector to take advantage of new vehicle technologies, there will need to be a national focus on developing new forms of electricity generation.

“Getting the UK electricity grid into into field in pretty much all of the areas we’re going to want to operate is not possible,” says Gutsell. “But if you can deliver in-field generation of fuels in some form, that provides a huge capability advantage. There’s some great ideas being tested at the moment with solar generation. There’s some great stuff that’s being innovated in the US in terms of in-field nuclear electricity generation, almost in containers.” And, Gutsell adds, there is work underway on in-field hydrogen generation. “If you can get a water source and electricity source, you can create green hydrogen. Unlocking from that traditional supply chain of shipping in fuel, because you can use netzero sources like electricity, is going to be really powerful.”

Military procurement is a decades long process. Vehicles that are being commissioned now, as the energy transition gets going, will still be in use when—if everything goes to plan—we are all living in a fossil fuel free society.

“As military planners, you’ve got to be acutely aware of that,” says Gutsell. “Typically you’re buying for some year’s time because the sector has very slow procurement cycles, and for many, many years of use. So there was a report out [in 2023] from the House of Commons select committee. There are about 1000 tanks and other military vehicles entering service in the next few years, that are going to have diesel engines. And they’re going to be in use until 2050, in many cases.”

It’s the role of engineers to help military purchasers ensure they are ready for the energy transition.

“In 2050, a diesel fuelled piece of military equipment is not going to have the same capability edge as a netzero piece of equipment that has been bought through in 2040. So you’ve got to plan for that now,” explains Gutsell. “So, at what point could you upgrade it? And how could we make our fossil fuel kit ready for upgrade? How could we start to modularize some of these capabilities?”

Delivery and procurement challenges

There are many big questions left to answer.

“We don’t know, in a number of sectors, what the fuel of the future will be. It may well be fuels we haven’t discovered yet. We’ve got to understand and do the right kind of foresight scanning and deliver that modularity,” says Gutsell. “There are considerations around that modularity, which you’ll need to build in upfront. We have to make sure that you can economically switch over those propulsion systems in 10 years, or 20 years, and maybe two or three times.”

Those questions will be answered by the private sector. One innovative field Gutsell has been working in is the E-VTOL, or electric vertical take-off and landing, segment. This has almost entirely been developed by private businesses.

“It used to be the military sector drove a lot of innovation. And you’d see that trickle through to the commercial sector, from the military and the space sector, which were both very closely tied. But increasingly, the commercial sector has started to drive innovation. In the vehicle space, that’s come from the private sector for private sector use. And increasingly in the aviation space, particularly around E-VTOLs, but other fuel sources—that’s coming from potential commercial sector applications. They’re the bulk users, they’re going to order thousands of vehicles, whereas the military now orders a lot less, as it’s become more technological.”

Some of the most exciting innovations often come from small, agile, businesses. But this approach to development does not fit well with military procurement processes.

“The challenge has traditionally been those procurement cycles. So we’re talking two, three, four, five, ten-year cycles. That’s not doable as an SME, you don’t have the funding to get through those cycles. You don’t have the funding for a delivery programme, where you might not be getting paid for that equipment for another two, three years,” says Gutsell. “Understanding and mapping where defence can have a real impact will be useful in targeting that funding.”