Some militaries have strategies to reduce their carbon emissions – but the latest data shows these are being dwarfed by the effects of spiralling arms spending. Stuart Parkinson investigates.
The recent NATO Summit in Türkiye ended with its usual declaration of “ironclad” military unity. The price exacted by President Trump for this unity was that European members and Canada had to continue to expand their already vast spending on rearmament programmes. These increased by a staggering $139 billion in 2025.
Noticeably missing from the declaration was any mention of the climate crisis – and especially not the effect the huge spending increases will have on carbon emissions. Only a few short years ago, NATO had been both warning about the security threats due to climate change and encouraging militaries to take action to curb their own carbon emissions. Some militaries had started to publish climate strategies. So how much action to reduce emissions have these strategies actually led to? And how is this action faring against a background of rapidly rising military spending?
In this article, I will summarise the findings of a newly-published study by Scientists for Global Responsibility (SGR), which examined the military climate strategies of 26 nations around the world, as well as NATO itself, and discuss the implications.
NATO’s extra carbon emissions
Although data is limited, the carbon footprint of the world’s militaries is estimated to be between 3.3% and 7% of global emissions. If they were a single country, militaries would probably have the fourth largest carbon footprint in the world – larger than Russia – and that doesn’t include the emissions from the impacts of war, such as the destruction of oil depots and forests, or post-conflict reconstruction.
International military spending is rising fast – especially within NATO, which last year set a target to raise budgets to 3.5% of GDP, with a further 1.5% GDP to be spent on broader ‘security measures’, by 2035. SGR research published last year concluded that, for each additional $100bn of military spending, the military carbon footprint would rise by about 32 million tonnes of carbon dioxide equivalent (tCO2e). Based on this, NATO’s extra military spending in 2025 alone could lead to additional emissions of around 44 million tCO2e. That’s similar to the total annual emissions of a country like Uruguay.
Our research suggests that the spending rises by 2035 could triple this figure. Significantly, these emissions would mostly occur in the international supply chains that militaries depend on, because (at least currently) most of the new spending is on manufacturing new weapons systems and related equipment. Hence, these increases would not be immediately visible in data on direct military emissions.
NATO climate commitments
In light of these rises, let’s look at the climate commitments that militaries have made, starting with NATO itself. In 2022, soon after the Russian invasion of Ukraine, the alliance committed itself to a target of net zero emissions by 2050, with a 45% reduction by 2030. The catch was that the targets did not apply to all the militaries of the 32-nation alliance, they just applied to the ‘NATO enterprise’, which is composed of a small number of buildings, planes, and ships that the central organisation directly manages.
Even given this very modest starting point, progress has been very poor. No reports on the carbon emissions of the enterprise have yet been published, and the net zero commitment is conspicuously absent from the relevant section of the NATO website, leading to concerns that it has been quietly abandoned.
National military climate targets
Turning to the climate commitments of national militaries, is the situation any better? Again, we found that some clear targets have been set, but coverage was limited in numerous ways. In our sample of 26 nations – including 20 NATO members – only 9 had set targets for the period up to 2035, and only 4 of these countries had targets covering all core emissions (direct emissions and those related to electricity generation, known as ‘Scope 1 and 2’). The other 5 countries had set near-term targets, but had exempted key sources of emissions. So, for example, Germany’s targets only covered 50% of core emissions, the UK’s targets only covered 42%, and France’s targets only covered 17%. Most frequently, the emissions excluded from targets were those from ‘mobile’ military activities: the gas-guzzling combat planes, warships, and armoured vehicles that are the most visible sources of pollution. Indeed, only 2 nations had set near-term targets consistent with a ‘best case’ trajectory of reaching net zero by around 2050.
However, as we saw in the case of the NATO enterprise, setting targets is only the first step. Carrying out emissions mitigation action and reporting on its progress is obviously also essential. Only 7 nations – Australia, Canada, Germany, Ireland, Norway, Switzerland, and the UK – are currently publicly reporting their military emissions, but among these some significant reductions have been measured. However, again, there are significant issues.
For example, Germany set a target to reduce the emissions from its military bases by 65% by 2030. By 2023 – the latest year for which data is currently available – these emissions were down by 82%. On the face of it, this seems very impressive – but we need to look closer. Firstly, the baseline year used was 1990 – which coincided with the end of the Cold War. So, during the 1990s, there were many base closures and a large reduction in active military personnel. While this has genuinely led to significant reductions in emissions, with the massive NATO-driven military expansion programme now underway, as we have discussed, these savings are in real jeopardy. Secondly, a large fraction of the reduction in electricity-related emissions has been achieved by decarbonisation of the national grid – a civilian undertaking – so the military has not had to take any action to achieve these savings. Hence the savings achieved by military action to intentionally reduce emissions are much more limited. Nevertheless, building energy efficiency improvements and onsite renewable energy projects at military bases have also reduced emissions – so at least these can be legitimately claimed as successful military climate action.
A similar story was seen in the UK. It had set targets to reduce its emissions from military bases by 30% between 2017 and 2025. By 2024, this target had been exceeded. However, again, much of the reductions had been achieved through decarbonisation of the national grid and military base closures. Indeed, new military facilities are being built to replace some of those that had been shut. While these will be more energy-efficient, and therefore have lower emissions, the construction-related emissions have not been included within the targets – a serious loophole.
Inspection of the UK emissions data reveals some other notable findings, this time on mobile military emissions. These have varied considerably over the past few years with, for example, a high in 2021 and a low in 2024. The high was caused by the UK’s ‘Carrier Strike Group’ – a flotilla of warships led by the huge Queen Elizabeth aircraft carrier – sailing to the Far East and back. The low was caused by a widespread reduction in activity by British warships and aircraft, caused in part by significant maintenance problems. Again, with a general increase in NATO exercises and deployments and UK patrols planned for coming years, higher levels of mobile emissions seem to be inevitable. Militaries are pointing to the possibility of reducing emissions using various technologies including so-called sustainable aviation fuels and drones, but the obstacles are considerable.
Of the 26 nations that we looked at in the study, two stood out as having achieved the highest rate of reductions in core military emissions to date: Ireland and Switzerland. It is unlikely to be a coincidence that these are also militarily neutral countries.
Emissions from supply-chain and war-fighting impacts
As mentioned earlier, supply-chain emissions are another crucial factor. Data from Norway and the UK indicate these could represent over 80% of the military carbon footprint, so measuring and setting reduction targets for these are key, especially given the NATO spending increases underway. However, of the 26 nations examined, only the Norwegian military has published a comprehensive assessment of its supply-chain emissions – but has set no reduction targets – while only Canada has set reduction targets, but has yet to publish any data on these emissions. Given the potential size of these emissions, it is striking just how little attention has been has been given to them.
A few arms companies have started to publish data on their carbon emissions and to implement action to control emissions, but again this is limited. Rather more significant is the way in which the whole sector has lobbied for, and achieved, major exemptions from climate measures, including in the European Union. This is obviously a major problem given the projected rises discussed above. Despite this, some arms companies have already started marketing themselves using the language of sustainability, viewing “decarbonisation as war-fighting opportunity”.
A further important flaw in military emission statistics is the lack of data on war-fighting impacts, such as destruction of carbon reservoirs or post-conflict reconstruction. No military currently reports on these, although valuable work is being carried out by academics and non-governmental organisations such as the Initiative on GHG Accounting of War and the Conflict and Environment Observatory.
Top military spenders
Of course, the biggest issue remains the behaviour of the top military spenders, like the United States, China, and Russia. Under the Biden administration, the United States did publish separate military climate strategies for the three branches of its armed forces: army, navy and air force. However, despite having lower ambitions than some of its NATO compatriots, these plans were abandoned by the Trump administration in 2025 as part of the broader attack on US climate action. As for China and Russia, no military climate strategies are known to exist.
Comparing falls in emissions with projected rises
Given the sparsity of data on military emissions, it is difficult to make robust comparisons between reductions due to military climate action and the increases that are underway due to spending rises. However, a few figures are indicative. In the 7 nations which have documented their military climate action, the total fall in annual core emissions as a result of this action has been about 5 million tCO2e, which has mostly occurred in Germany due to post-Cold War base closures. If we assume that this also led to commensurate reductions in supply-chain emissions, and that these emissions make up 80% of military carbon footprints as discussed above, then the total reduction will be in the region of 25 million tCO2e.
If we compare this with our estimate above of the increase in emissions due to the rise in NATO military spending in 2025 (excluding the United States) – 44 million tCO2e – we can see that a single year’s additional military spending has overwhelmed the emission cuts that have taken many years of action to be achieved.
The future of climate action and security
When military carbon reduction plans first started being published around 2020, they faced an uphill struggle. Military adaptation to a more extreme climate was generally favoured over efforts to reduce emissions. Militaries also seemed more eager to publicise these plans to improve their public image rather than implement robust measures.
However, since then, the situation has become considerably worse, with military spending spiralling upwards, many climate efforts discarded, and emissions (as far as we can tell) growing rapidly. While a few military efforts – such as building energy efficiency programmes and onsite renewable energy projects – have been moderately effective and need to be continued and expanded, these are being overwhelmed by unmonitored increases in supply-chain emissions and among militaries which are not interested in tackling emissions.
So the main focus of policy-makers in this area needs to be much less on technological measures, and much more on peacebuilding and related efforts to stop and eventually reverse confrontational behaviour and associated military spending rises. Doing this – although admittedly very difficult – would obviously help to create a more peaceful world as well as a more sustainable one.
As the Paris climate target of 1.5⁰C looks certain to be passed within a few years, and this summer’s extreme weather gives us a taste of what will soon be regarded as ‘normal’, the urgency is clear. The climate crisis should no longer be marginalised by security policymakers, but needs to be given high priority.
Dr Stuart Parkinson is executive director of Scientists for Global Responsibility (SGR), a climate scientist, a former engineer in the arms industry, and author of numerous influential reports on climate change and the military.
The views and opinions expressed in posts on the Rethinking Security blog are those of the authors and do not necessarily reflect the position of the network and its broader membership.
Image Credit: Royal Navy, LPhot Belinda Alker. HMS Queen Elizabeth and her Carrier Strike Group (CSG) form up for the first time, October 2020. The CSG’s 49,000 nautical mile maiden deployment to Japan and back caused a surge in UK military emissions in 2021.
