At the very moment when humanity most needs unprecedented international cooperation to tackle the climate crisis, the world is sliding deeper into militarism, confrontation, and war.

That slide is visible not only in soaring military budgets but in the increasingly casual language with which political leaders discuss destruction. Global military spending reached a record $2.718 trillion in 2024, the sharpest annual rise since the end of the Cold War. Amid the conflict with Iran, Donald Trump reportedly said the United States might strike Iran’s Kharg Island oil export hub again “just for fun”. Whether intended as policy or bravado, the phrase is morally grotesque. It captures a political culture in which the devastation of distant places can be discussed with flippancy — as if the killing of foreigners scarcely counts.

War is not only a human catastrophe; it is an environmental one. The increased greenhouse gas emissions from the war in Gaza alone are estimated to equal those of 36 small countries. Militarisation consumes immense quantities of fuel, energy, steel, concrete, rare materials, scientific talent, and public wealth. Fear, rivalry, and military threat run directly counter to the international cooperation on which building a sustainable world depends. The sustainability of the planet and the conduct of international relations can no longer be treated as separate issues.

Even without active conflict, military preparations absorb resources on a colossal scale. The Stockholm International Peace Research Institute (SIPRI) warns that rising military expenditure can undermine sustainable development by diverting resources from urgent social and environmental needs. Funding devoted to weapons is funding withheld from renewable energy, flood protection, resilient agriculture, public health, ecological restoration, and support for those countries most exposed to climate disruption. Every step further into military escalation is a step away from the practical work of safeguarding a liveable future.

The environmental crisis is itself heightening international tension. Droughts, crop failures, water shortages, extreme heat, and rising seas will sharpen social and political pressures by creating scarcities and displacing growing numbers of people. In a world governed by mutual fear and armed rivalry, those pressures are likely to turn into hostility, exclusion, and violence. In a vicious circle, ecological breakdown will feed conflict, and conflict will accelerate ecological breakdown.

But the contradiction runs deeper still. Modern life has bound humanity together more tightly than ever before. Our international economic interdependence encompasses not only energy supplies but food systems, technologies, financial networks — every aspect of how we live. Our weapons threaten those we depend on for both necessities and the good things of life, just as theirs threaten us.

No nation can stabilise the climate alone. No nation can protect oceans, forests, biodiversity, freshwater systems, fertile soils, or the atmosphere in isolation. No arsenal can defend a people against a collapsing climate. No wall can hold back planetary breakdown. Only cooperation can do that. Mutually supportive international relations can no longer be treated as separate from sustainability — they are its essential precondition.

A politics that can speak lightly of bombing an oil hub “just for fun” is not merely callous. It is fundamentally unfit for an age of planetary emergency. The environmental crisis demands a historic shift in the spirit of international relations: from rivalry to cooperation, from armed threat to mutual support, from domination to shared responsibility, and from preparation for war to preparation for survival.

Here a more uncomfortable question must be asked. In our globally interdependent world, what is the moral difference between killing large numbers of innocent people abroad and killing them at home? Why is one still seen as strategy, deterrence, or collateral damage, while the other would be regarded as an unspeakable atrocity? Distance is no longer a barrier to moral culpability, any more than foreign nationality diminishes human worth.

Climate change, ecological breakdown, water scarcity, soil depletion, habitat destruction, and the destabilisation of the natural systems on which all life depends are not threats confronting one nation alone — they confront us all. Yet the international order remains organised around armed hostility, strategic competition, and the assumption that security rests on the capacity to threaten, intimidate, and destroy. This is not merely moral bankruptcy; it is irrational self-harm, rooted in a failure to recognise that the present is not like the past.

The realism this moment demands lies in acknowledging that our futures are inextricably joined, that our security is shared, and that no nation can preserve its own safety on an unsafe planet.

The environmental movement should say this without equivocation: the wealth now poured into arms, deterrence, and military rivalry must be redirected towards mutual cooperation, ecological repair, and shared survival. Our task is to turn adversaries into partners, and to rebuild international relations not around the means of destruction but around the means of mutual survival.

Some will say this is unrealistic. But what is truly unrealistic is to imagine that humanity can survive ecological breakdown while remaining trapped in systems of military confrontation shaped by power politics, empire, and war. What is unrealistic is to believe that a planetary emergency can be met through rivalry and arms races — by pouring wealth into hostilities that drive the living world towards collapse.

We will not find the cooperation to prevent the destruction of the planet while we continue trying to destroy each other.

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