Will the UK Reduce its Military Carbon Emissions?

The British military is taking some steps to curb its impacts on the climate. But its efforts will fail to have a significant effect without major changes in the UK’s national security policies, argues Dr Stuart Parkinson of Scientists for Global Responsibility.

The Ministry of Defence recognises that the climate crisis is a global and national security threat. In its regular publication Global Strategic Trends, for example, it highlights the threats from the “increasing disruption and cost of climate change”. The MOD also recognises the need to reduce its own carbon emissions – and has taken steps to reduce these in line with the Greening Government Commitments (GGCs). But there are many reasons to doubt that the scale of action being undertaken by the MOD matches the scale of the climate threat – or that the government’s approach to security as a whole will take us to a safer world.

How big are UK military carbon emissions?

Let’s start by looking at the carbon emissions of the UK military. The MOD reports on these in its annual report. For example, the headline figure it quoted for the financial year 2017-18 was 0.94 million tonnes of carbon dioxide equivalent (tCO2e). But this is only a small part of the picture. Closer examination reveals that these figures are only for ‘Estates’ plus ‘Business travel’, i.e. emissions from all the property owned by the MOD and civilian travel for MOD business. It does not include the carbon emissions related to any use of military equipment. So, only if the reader is able to understand the technical annexes at the end of the report – and then do some calculations of their own, taking into account some data gaps – will they be able to obtain an estimate for the total direct emissions of the MOD. I calculated this myself for a report published by Scientists for Global Responsibility (SGR) and Declassified UK in May and I arrived at a total of 3.03 million tCO2e – more than three times the MOD’s headline figure.

But even this figure is only part of the picture. What about the emissions of the UK’s arms industry? Or the MOD’s other suppliers? Or their supply-chains, both in the UK and abroad? In short, what is the carbon footprint of UK military spending? In my report, I analysed a wide range of data from industrial, academic and government sources. Although there were many shortcomings in the publicly available data, I was able to come up with estimates of the different components, and of the total carbon footprint itself.

Hence, I estimated that the total carbon emissions of the UK military, the British arms industry, and their supply-chains within the country amounted to 6.46 million tCO2e. Including the full lifecycle – such as overseas manufacturing and raw material extraction – led to a total carbon footprint for UK military spending of approximately 11 million tCO2e. This was more than 11 times the MOD’s headline figure – and similar to the emissions that six million average British cars produce in a year.

Reductions in UK military carbon emissions so far

Returning to the MOD’s annual report, it describes the large reductions over the past few years in its headline carbon emissions. In particular, against a target to reduce these emissions by 39.9% over a ten-year period from 2009-10, it had achieved 42% over the first nine years. But, as we have seen, these reductions cover less than one-eleventh of the military carbon footprint. Indeed, looking more closely at just these emissions, the figures are even less impressive. For example, the National Audit Office (NAO) recently pointed out that half of these emission reductions were achieved by a combination of the shift within the national UK electricity sector to renewable energy and a sell-off of MOD properties. So only half of these reductions were achieved through MOD programmes specifically aimed at saving energy and/or carbon emissions. The NAO also pointed out that some of the Ministry’s other energy-saving programmes had had to be delayed or cancelled due to the MOD’s very large deficit on its equipment plan. This deficit continues to be a major problem for the MOD so, without marked changes in this plan, it will continue to act as a break on emission reduction efforts.

Turning to the carbon emissions of the MOD’s use of its equipment – i.e. in military operations – the reductions in this area have been at a significantly slower rate. And, while energy efficiency measures in ships, planes and ground vehicles have helped these reductions, a key factor has been the recent decrease in overseas military missions. The MOD has yet to publish an assessment of which of these two factors were most important, but the suspicion is that the reduction in war-fighting has made a large contribution. So, a strategy of not fighting wars keeps emissions significantly lower – not much of a surprise there!

The MOD has also started efforts to reduce the carbon emissions of its supply chain – through, for example, the use of the government’s mandatory sustainable procurement buying standards. Unfortunately, it is not monitoring compliance with these standards, so it has no idea whether this is having any positive effect.

Will the UK military comply with national ‘net-zero’ carbon targets?

In 2019, Theresa May’s government committed the UK to reduce its carbon emissions to ‘net-zero’ by 2050. Boris Johnson’s government has yet to decide whether the MOD will aim to comply with this, or whether it will try to offset the emissions elsewhere. Both would offer serious challenges.

In the near-term, Britain plans to significantly increase its military budget, bring into full operation two huge new Queen Elizabeth (QE) class aircraft carriers – powered by a combination of natural gas and diesel – and continue with military strategies which involve major international force deployments.

The likelihood is that the first priority of any increases in the military budget would be to deal with the funding shortfall on the MOD’s equipment plan – which stands at £6 billion over the period to 2024 – thereby bringing into service more quickly more military vessels and vehicles with the associated increase in fossil fuel consumption. The QE aircraft carriers in particular are huge consumers of energy – each propelled by two large gas turbines and four diesel engines, with a combined capacity of over 110 megawatts (MW), a similar scale to supplying energy for a medium-sized town. Each is designed to carry up to 72 aircraft, including new F-35 strike planes and helicopters. And these ships do not sail alone: when deployed as part of a ‘Carrier Strike Group’ they would be accompanied by some combination of frigates, destroyers, submarines, mine-hunters and supply vessels.

Furthermore, routine deployment of the UK military far from British shores results in high carbon emissions. For example, Britain has a network of overseas bases, many of which are being expanded, while 20% of the Royal Navy’s operating fleet is deployed to the Middle East at any one time.

And if the UK government took the decision to mount a major war-fighting operation – such as that seen in Iraq or Afghanistan – carbon emissions would of course surge.

Set against these trends, the MOD’s energy efficiency programmes – even if they were markedly expanded as part of a larger military budget – would not offer compensation on anything like the scale required.

Two other current technological trends could lead to a sizeable reduction in UK military carbon emissions. The first is the continued expansion of renewable energy in the civilian economy – which is used by UK military bases and arms companies. However, given that UK climate policies currently fall well short of delivering emissions targets – placing this extra burden on civil society will only make that job harder.

A second technological trend which may reduce carbon emissions is the greater use of smaller robotic craft – especially aircraft – instead of human-piloted vehicles. These ‘drones’ tend to be more energy efficient – but their use is already raising a wide range of additional ethical issues, not least the very real possibility of an arms race in autonomous weapons or ‘killer robots’.

A further technological option is the expanded use of lower carbon nuclear power in a wider range of military vessels. However, poor economics, together with major technical and environmental problems, makes this option unattractive – even to many military advocates.

One area that is becoming increasingly attractive to ‘hard to reduce’ sectors are the so-called ‘negative emissions’ options. These range from tree-planting to carbon capture and storage technologies – but in general either these are strongly limited by land availability or the technologies are at an early stage of development.

A different approach

There are, however, much more promising alternatives – which tackle both insecurity and environmental sustainability.

The first would be to cut back on military technologies, starting with the ones at the most ‘offensive’ end of the weapons spectrum – i.e. those which have the highest destructive capabilities and/or the longest ranges.  Nuclear-armed missiles are obviously top of this list – especially as just one Trident submarine load would be enough to cause a catastrophic ‘nuclear winter’ threatening the whole of human civilisation, as well as natural ecosystems. Aircraft carriers would also be high on this list, as would long-range strike aircraft like the new F-35s. Cuts in these technologies would help to reduce international arms races and, in most cases, markedly reduce fossil fuel use and thus help tackle climate change.

The second, complementary approach would be to focus security spending on tackling the roots of conflict, known as ‘sustainable security’. So, in addition to peacebuilding measures in war-torn countries, diplomacy, and humanitarian aid, the UK would strengthen its efforts to curb factors which can spark or multiply conflict. For example, it would do more to reduce inequality and end international poverty, and it would curb the UK’s unsustainable consumption of energy and material resources, thereby helping to reduce climate change and other global threats, including pandemics.

In summary, the UK military acknowledges the threat from climate change and the need for it to reduce its own carbon emissions – but its response is not up to the task. Only major changes in security policy – including cutting polluting, aggressive military technologies and focusing on tackling the roots of conflict – will deliver the scale of action required.


Dr Stuart Parkinson has been Executive Director of Scientists for Global Responsibility since 2003. He is an engineer and physicist with a PhD in mathematical modelling of global climate change. He has been an expert reviewer for the Intergovernmental Panel on Climate Change (IPCC) and provided advice to UK negotiators to the UN climate change convention. He is the author of many reports for SGR, including the recent The Environmental Impacts of the UK Military Sector, which this blog summarises.


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: U.S. Air Force photo/ TSgt Boyd Belcher.

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