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The Tension Between Militarisation, Security and Climate Change

04.11.25 | Amber Agyemang

Europe’s shift in attention for defence focussed security

It will not be soon forgotten: the June 2025 NATO-top in the Hague where the heads of the 32 NATO countries came together to discuss the future of the alliance. Under pressure from US president Trump, members agreed to increase annual defence expenditure from 2% to 5% of GDP over the coming decade, raising defence spending to levels not seen since the Cold War. Although 1.5% of the agreed 5% raise can be directed to “defence-related expenditure”, such as critical infrastructure, the remaining 3.5% is supposed to be achieved entirely through core spending on arms and troops. For most members this will require a stark increase in military expenditure, as most are still hovering around the 2% mark, with some even not reaching the initial commitment. This historic agreement signals a shift in Europe’s focus to defence and security. With the 2022 Russian invasion of Ukraine, and with the US and Europe facing greater insecurity due to Trump’s claims that he will shift his focus to domestic issues, Europe is directing more attention to its potential insecurity. While before this shift, Europe was primarily focussed on climate decarbonization, economic integration and cooperative interdependence over hard defence.

Alarmingly, this change of attention comes at the cost of other issues. With limited state budgets, capacity and time, the shift in attention to defence means a decrease in attention to climate action. This, while climate change has been named a major security threat and the environmental impacts of military expenditure remain understudied. This raises the question what the connections are between climate change, militarisation and security. This article examines the tension between militarisation and climate change and argues why Europe should have climate action at the core of its security mission.

How climate change impacts security

The field of climate security has long been conducting research on how climate change increases conflicts and therefore negatively impacts (inter)national security, which is called the climate-security nexus. This nexus describes how climate change impacts, exacerbate existing social, economic, and environmental challenges in many contexts, which can contribute to insecurity at local levels, or even internationally. Security concerns linked to climate change include impacts on food, water and energy supplies, increased competition over natural resources, loss of livelihoods, climate-related disasters, and forced migration and displacement.

One geographic area that has given a lot of insight in the study on the climate-security nexus is the Sahel region, which faces temperatures rising 1.5 times faster than the global average. Most small-holder farmers and herders in this area are reliant on rain-fed agriculture, which is especially sensitive to changing rainfall patterns. Climate change has resulted in an increase in water scarcity, which fuels conflicts between farmers and herders and strains agricultural productivity. Scarcity of water and food has resulted in forced migration which led to further tensions and made communities more vulnerable to extremist groups. Although climate change does not directly lead to more terrorism and other forms of violent conflict, factors associated with it have appeared to be a catalyst to instability in the entire area, with cascading effects on the overall global security. As António Guterres described it: “Climate change is not the source of all ills, but it has a multiplier effect and acts as an aggravating factor for instability, conflict and terrorism”.

The understudied impacts of militarisation on climate change

In contrast to the impacts of climate change on security, the impact of militarization on climate change is an understudied field. The main reason for this is a lack of transparency because governments are not obliged to report on the emissions generated from military activities to the UNFCCC. Military emission reporting was kept out of the 1997 Kyoto Protocol, under pressure of the US. The 2015 Paris Agreement made emissions reporting voluntary. Only a handful of countries do report information on their military emissions, however data is often patchy or completely absent.

Amidst the uncertainty due to missing data, experts are developing ways to estimate the impact the military has on climate change. A 2022 report by the Conflict and Environment Observatory (CEOBS) estimates the total military carbon footprint at 5.5% of global emissions. This means that if all the militaries in the world combined were a country, it would have the fourth highest carbon footprint, with only China, the US and India as higher emitters. If this estimation is true, the global military emission footprint is larger than that of shipping (3%) and civilian aviation (2%). Militaries, arms industries and wars themselves have a high carbon footprint. Fighter jets, tanks and warships are uniquely fuel-hungry and lead thus to a high level of direct emissions of the military. Additionally, military equipment also relies on supply chains of materials like aluminium, steel and critical raw materials, which production, refinement and transport are carbon intensive. Furthermore, military spending will also continue our system's dependence on fossil fuels, due to their military value and the lifetime of military equipment being 20-30 years. If we make more fuel-running tanks now, we will be needing fuel to power them for the coming decades.

An increase in military expenditure will increase all these emissions. Although it is hard to already predict what exactly the money will be spent on, Scientists for Global Responsibility (SGR) published a report estimating that the planned NATO military expenditure increase will lead to a rise of about 130 million tCO2 annually, similar to the total emissions of a country the size of Brazil each year. This will push the estimated 5.5% military contribution to the global footprint far higher, while it does not even take into account the emissions of actual conflict and the environmental impact of war.

There is no consensus on the question if an increase in global military spending will actually guarantee security. More money spent on defence fuels arms races, deepens mistrust among countries and has cascading effects leading to a potential higher risk of conflict. And military conflicts have a far greater environmental impact than just that of an increase in military expenditure. If shown a picture of the atomic bombs on Hiroshima and Nagasaki or the complete decimation of Gaza, one can easily imagine how destructive war is on the environment. Polluting water basins and soils with highly toxic material, white phosphorus usage and the eradication of vegetation all contributed to experts describing Israel’s destruction of Palestinian land an “ecocide”. The destruction of the environment is often a strategy in war, with enormous impacts on climate change.

Even if an increase in military expenditure does not lead to more conflict, it still redirects public money away from climate action. The NATO commitment to raise defence spending by 3.5 percent of GDP will require most member states to redirect substantial portions of public funds toward arms and personnel, leaving less available for other critical priorities. Education, health services, social welfare programs, international development assistance and climate mitigation and adaptation efforts could all see their budgets squeezed. This is particularly concerning because investment in climate action and development abroad not only addresses environmental and humanitarian needs but also contributes to long-term stability and security. By prioritizing short-term military spending over these areas, governments risk undermining the very resilience they aim to protect, creating gaps in human, economic and environmental security that can have cascading effects for society at large. As said by US president.

These dynamics reveal a dangerous feedback loop between climate change and militarisation. As climate impacts intensify, governments perceive growing instability and respond by strengthening military capacities. Yet this very process of militarisation, through its massive carbon footprint and resource demands, accelerates the climate crisis that fuels insecurity in the first place. Instead of breaking the cycle, the current approach risks reinforcing it: more climate disruption drives more military spending, which in turn deepens the causes of that disruption. Understanding this loop is essential if Europe is to build genuine, lasting security rather than an illusion sustained by ever-rising defence budgets.

A broader understanding of security

Europe urgently needs to rethink what security means in an era of accelerating climate disruption. Military expenditure should not be exempt from climate accountability. National governments must require full and transparent reporting of military emissions under the UNFCCC, in line with recommendations from Scientists for Global Responsibility. Only with reliable data can military planning be aligned with national and international climate targets.

Additionally, a security strategy fit for the future would direct investment toward measures with dual civilian and defence benefits. Strengthening rail infrastructure, energy-independent bases and resilient supply chains contributes to both climate mitigation and strategic autonomy. It will lessen our dependence on fossil fuels from foreign powers, such as gas from Russia. By scaling up our renewable energy systems, we can produce the energy for our own demands, strengthening long-term resilience. At the operational level, greening military logistics and procurement would reduce emissions while improving long-term operational resilience, rather than reinforcing fossil fuel dependency for decades to come.

This is not to suggest that militaries have no constructive role to play in responding to the climate crisis. They have been essential in disaster relief efforts over the past decade, such as flood evacuations in Germany and wildfire responses in Greece. These capabilities do not require maintaining large, fossil-fuel-dependent militaries, but indicate that the focus should be on adaptive capacity building and increasing climate resilience.

However, democratic oversight is essential. Citizens and civil society have a role in ensuring that rising defence budgets are not financed at the expense of climate mitigation, climate adaptation or international development. By organizing events to raise awareness, discussing the topic in our communities and pressuring our politicians, we can create public discussion on these issues. Polluters, including the military sector, should no longer be shielded from taxation and need to commit to carbon pricing. This would incentivise cleaner practices, generate revenue for climate and security priorities and prevent the burden from falling on essential public service.

This scrutiny matters because the drivers of higher military spending are not always strategic. There are a number of reasons why Trump pushed to increase the NATO commitment, but we should not forget that he was first and foremost a businessman with stakes in the US military industry.

Although the impacts of climate change are uneven, their consequences are interconnected. A stable climate is a precondition for lasting security. Climate action must therefore move from the margins to the core of Europe’s security mission. The question is whether we act in time. Shall we?

This article is part of The Outside World, ftrprf’s very own research center.

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