This text is based on analysis by Duncan Depledge in The Conversation and my reflections also published in Swedish via Tidningen Global.

TLDR: War and climate change have become as two sides of the same coin. Drawing on analysis by Duncan Depledge (Loughborough University), this piece shows how warfare worsens the climate crisis through emissions and environmental destruction, and how climate change, in turn, increases pressure on societies and drives more frequent military deployments for disaster response. It is also about why armed forces themselves must adapt to a warmer and also more insecure and dangerous world. The question is no longer if climate affects war, but how to change and adapt to the new realities. 

War and Climate 

In 2024, for the first time, the global average temperature pushed past 1.5°C above pre-industrial levels. At the same time, brutal wars raged as in Ukraine, Gaza and Sudan. As Duncan Depledge, senior lecturer in geopolitics and security at Loughborough University, argues, we can no longer make sense of war without seeing it in the light of the climate crisis.

War and climate change interact in multiple ways where warfare drives massive emissions and ecological damage, climate stresses can intensify humanitarian crises and instability and also where military organisations are being forced to operate under new conditions shaped by extreme weather and shifting energy systems.

1) War Makes the Climate Crisis Worse

Researchers and civil society groups have begun to quantify war’s climate footprint. Estimates suggest that global military emissions could exceed those of entire large countries. The U.S. military alone, if treated as a “country,” would rank between Peru and Portugal among top emitters. These figures rely on partial reporting, which underlines the need for transparent, standardised accounting of military emissions.

War also undermines international climate cooperation. Following Russia’s full-scale invasion of Ukraine, scientific collaboration in the Arctic collapsed, leaving crucial climate data uncollected. Every new cycle of rearmament and reconstruction must therefore be weighed not only in costs and tonnes of CO₂, but also in lost knowledge and weakened global cooperation.

2) The Climate Crisis Demands Military Responses

Armed forces are increasingly called upon to support civilian authorities during climate-related emergencies—fighting wildfires, reinforcing flood defences, evacuating communities and delivering aid. The debate over “climate wars” remains contentious because violence is ultimately a human decision. Yet, regardless of causality, the number and intensity of extreme events are rising, stretching both civilian and military capacities and forcing hard choices between defence spending, welfare priorities and climate adaptation.

3) Militaries Must Adapt

Calls for demilitarisation are unlikely to be heeded in the near term. Instead, armed forces must adapt to function in a changed climate while cutting fossil-fuel dependence. Bases, equipment and personnel need to withstand heat waves, wildfires, droughts, downpours and rising seas. In 2018, two major U.S. hurricanes caused more than eight billion dollars’ worth of damage to military infrastructure as an example of mounting costs if adaptation lags. At the same time, the energy transition will reshape how militaries are organised, supplied and deployed from fuel chains and logistics to power generation and electrified systems.

Climate Perspectives  on War and Peace

Carl von Clausewitz famously wrote that war’s nature is enduring, but its character evolves with the times. The climate crisis is such a transformative force. As Depledge stresses, we must rethink strategy to shrink war’s climate footprint and reduce the risk that climate change will drive future instability. War and climate are no longer separate debates; they are two sides of the same global question about security and human well-being in a rapidly warming world.

Concluding Reflections

Security in the 21st century has to be defined in more complex and multi-level ways. Climate security is also about whether people can live safe, dignified lives amid a fast-warming climate. That demands a new institutional contract between defence, diplomacy, development, and decarbonisation. For example, through transparent accounting of military emissions, serious investment in civilian preparedness, and armed forces designed to operate and to help societies recover in harsher conditions with fewer fossil fuels. The climate crisis will keep reshaping the character of war, whether we acknowledge it or not. The strategic choice before us is to adapt deliberately and to use that adaptation to lower risks, protect civilians and align security with a sustainable future.

Thanks for reading. Please follow my blog, write your feedback, and support my writing.