The growing evidence showing militarism is the single most ecologically destructive human endeavour

‘We are the generation that will be accused of intergenerational sabotage in years to come, because we have consumed so far beyond what is sustainable’

As the world heats up, so too do the risks of armed conflict. In 2022, a total of 56 countries worldwide experienced violent conflict, while the number of resultant fatalities that year was the highest in more than four decades.

In all probability, 2023 was even worse, given the bloody conflict that has erupted in Gaza since last October, one that threatens to escalate into a regional conflagration. As tensions escalate, so also has military spending. This has risen continuously since the late 1990s, hitting an astonishing $2.24 trillion (€2.07 trillion) worldwide in 2022.

Researchers now estimate that some 5.5 per cent of total carbon emissions are directly attributable to the world’s militaries. This is greater, for instance, than all global aviation. In fact, were the military a country, it would be the world’s fourth largest single emitter.

Its environmental impacts go far beyond simply tallying emissions. “Militarism is the single most ecologically destructive human endeavour”, according to sociologist Prof Kenneth Gould.


Exact details are, however, difficult to obtain, as much military activity is shrouded in secrecy. At the insistence of the United States, the carbon impacts of the world’s militaries were specifically excluded from the 1997 Kyoto protocol. The Paris Agreement on climate change in 2015 only requires “voluntary” reporting of military-related emissions, and there was no tally of such emissions in the recent Cop28 conference in Dubai.

While in the past, conflicts arose from a wide range of causes, today these risks have been amplified by global environmental destabilisation. “I see climate change as the overarching existential threat, one that dwarfs so many other issues,” says Mark Mellett, vice-admiral and former chief of staff of the Defence Forces.

As climate change intensifies, “we are going to see extraordinary penalties in terms of resources, in terms of people being dislocated. One degree of temperature rise will impact billions, not millions, yet we’re on track for that, with current projections of probably 2.7 degrees”, Mellett says. “This is an extraordinary future.”

Mellett, who has a PhD in environmental governance, believes the most critical climate impact coming down the tracks is forced migration which will, he believes, “challenge the cohesion of the institutions of the European Union; the only way it can be addressed is through mitigation”. Forced migration, he stresses, is “only a symptom of a much more serious problem that needs to be dealt with at source”.

The relationship between climate change and conflict is complex and non-linear. The US military, by far the world’s largest, classifies climate as a “threat multiplier”. The increasing frequency and intensity of weather disasters is putting a strain on military resources, as they are typically among the first responders in disaster zones. In addition, sea-level rise, hurricane damage and extreme flooding events have cost the US military billions of dollars in recent years in direct damage to bases and equipment.

An international study of the 25 countries worldwide reckoned to be most vulnerable to climate impacts found 14 involved in conflict. Many of these are in sub-Saharan Africa, a region of the world that has been already severely impacted by climate change.

The irony for countries such as Yemen, Mali, the Democratic Republic of Congo and the Sahel region is that they have contributed only a negligible amount of the carbon emissions that are now devastating their regions, notes Dr Rory Finegan, assistant professor of military history and strategic studies at Maynooth University.

It is the high-emitting countries and regions, including Europe and the US, that bear the brunt of responsibility for climate damages. This was, for the first time, addressed at Cop28 with the establishment of a “loss and damage” fund to help compensate countries for climate impacts not of their making.

However, the total so far committed to this fund is about €700 million, a veritable drop in the bucket measured against climate impacts already running into hundreds of billions of euro annually.

A major study published in 2020 in the journal Nature Sustainability found what its authors described as the human climate niche is surprisingly narrow. As global temperatures continue to climb, the study projected that between one and two billion people will be facing “unlivable” temperatures later this century, leading to forced migrations on a scale never before experienced by humans.

The social, political, economic and security implications of such a large movement of people across national borders are almost unimaginably severe. While climate and ecological destabilisation are clearly major risk factors increasing the risk of armed conflict, the environmental impacts of conflict are equally acute.

“Down through the millennia, a scorched earth policy was often among the military tactics being used,” adds Finegan, who served in the Defence Forces for 36 years before moving into academia. “You are now seeing this being used in a lot of the African conflicts, including in Chad and the DRC, where crops are being deliberately destroyed and wells being poisoned; this all just feeds into the cycle of misery.”

According to the UN High Commissioner for Refugees (UNHCR), in the past decade, the number of people forcibly displaced has doubled to almost 80 million worldwide, comprising 35 million refugees and 45 million internally displaced. This data predates both the Ukraine and Gaza conflicts, so it is likely an underestimate.

While forced migration as a consequence of climate change represents a vast threat to global security in the medium term, equally pressing and related issues include acute water shortages as well as reductions in global food production as a result of ever more destructive extreme weather events.

Another study in Nature Sustainability last year found conflicts involving water have risen sharply since 2000. In the decade to 2010, there were rarely more than 25 incidents a year globally. By 2018, this had increased five-fold, to more than 125 – while in 2022, it doubled again, to just more than 250.

The devastating civil war that has raged in Syria since 2011 was triggered at least in part by acute water shortages that followed the most severe regional drought in some 800 years. A World Weather Attribution study found that this drought was made 25 times more likely as a result of climate change.

The double irony of climate and conflict is the feedback loop that connects them. Armed conflict destroys infrastructure and can lead to widespread contamination of farmland and waterways. Conflict often forces farmers to abandon their fields and livestock, which in turn exacerbates the very conditions, such as hunger and water shortages, that stoke a vicious cycle of further conflict.

Some of this conflict arises between pastoralists and settled farmers, as they are pushed into competition for land and access to water as a result either of climate change or forced displacement arising from warfare.

A further element increasing pressure, Mellett says, is “the large rise in population that is happening in theatres like Africa”. The continent’s population has grown more than five-fold since 1960 and, barring disasters, Africa’s population is expected to double by 2050.

Since the end of the second World War, Europe in particular has enjoyed decades of peace and security. “That’s all in the crosshairs now, as we move forward with these new temperature profiles, because significant parts of the world will become uninhabitable”. In international law, there is no clear recognition of what constitutes a climate refugee, he underlines.

We are, Mellett adds, “a generation that will be accused of intergenerational sabotage in years to come, because we have consumed so far beyond what is sustainable – it’s greedy, frankly. If we don’t live sustainably, we are accepting that we simply don’t care about future generations.”

The ecological scars of warfare can last for decades. Iraq is still dealing with the fallout from the widespread use of depleted uranium by US troops in the 1990 Gulf War. Finegan says the “deliberate use of chemical warfare by the US in Vietnam, where large tracts of the jungle were defoliated with Agent Orange, still has very tragic residual effects on the Vietnamese population”.

While long-range forecasting is fraught with uncertainty, it seems inevitable the 21st century will be defined by growing political tension and conflict as billions of people struggle for scarce resources and for survival on a rapidly heating, ecologically depleted planet.

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