Three reasons why the climate crisis must reshape how we think about war

With geopolitical tensions rising and the number of conflicts increasing, it seems unlikely that calls for demilitarisation will be met any time soon. This leaves researchers with the uncomfortable prospect of having to rethink how military force can – and ought to be – wielded in a world simultaneously trying to adapt to accelerating climate change and escape its deep dependence on fossil fuels

Earth's average temperature rose more than 1.5°C above pre-industrial levels in 2024 for the first time – a critical threshold in the climate crisis. At the same time, major armed conflicts continue to rage in Ukraine, Gaza, Sudan and elsewhere. What should be increasingly clear is that war now needs to be understood as unfolding in the shadow of climate breakdown. The relationship between war and climate change is complex. But here are three reasons why the climate crisis must reshape how we think about war.

War exacerbates climate change

The inherent destructiveness of war has long degraded the environment. But we have only recently become more keenly aware of its climatic implications. This follows efforts primarily by researchers and civil society organisations to account for the greenhouse gas emissions resulting from fighting, most notably in Ukraine and Gaza, as well as to record emissions from all military operations and post-war reconstruction.

One study, conducted by Scientists for Global Responsibility and the Conflict and Environment Observatory, has made a best guess that the total carbon footprint of militaries across the globe is greater than that of Russia, which currently has the fourth-largest footprint in the world.

The US is believed to have the highest military emissions. Estimates by UK-based researchers Benjamin Neimark, Oliver Belcher and Patrick Bigger suggest that, if it were a country, the US military would be the 47th-largest emitter of greenhouse gases in the world.

This would put it between Peru and Portugal. These studies, though, rest on limited data. Sometimes partial emissions data is reported by military agencies, and researchers have to supplement this with their own calculations using official government figures and those of associated industries.

There is also significant variation from country to country. Some military emissions, most notably those of China and Russia, have proved almost impossible to assess. Wars can also put international cooperation on climate change and the energy transition at risk. Since the start of the Ukraine war, for instance, scientific cooperation between the west and Russia in the Arctic has broken down.

This has prevented crucial climate data from being compiled. Critics of militarism argue that the acknowledgement of war's contribution to the climate crisis ought to be the moment of reckoning for those who are too willing to spend vast resources on maintaining and expanding military power. Some even believe that demilitarisation is the only way out of climate catastrophe.

Others are less radical. But the crucial point is that recognition of the climate costs of war increasingly raises moral and practical questions about the need for more strategic restraint and whether the business of war can ever be rendered less environmentally destructive.

Climate change demands military responses

Before the impact of war on the climate came into focus, researchers debated whether the climate crisis could act as a “threat multiplier”. This has led some to argue that climate change could intensify the risk of violence in parts of the world already under stress from food and water insecurity, internal tensions, poor governance and territorial disputes.

Some conflicts in the Middle East and Sahel have already been labelled “climate wars”, implying they may not have happened if it were not for the stresses of climate change.

(Author is from Loughborough University)