The stunning pivot the United States just executed in the direction of Russia puts huge pressure on Ukraine and the rest of Europe, leaving European countries to scramble and massively shore up their own defence capacities. War in Ukraine and elsewhere rages on, military expenditures shoot up everywhere; how much of a blow to climate & sustainability efforts does this deliver, and what can be done about it?

The first consequences of war that come to mind are human life loss and large-scale destruction, and rightfully so. However, the ecological, environmental and climate costs that are suffered are staggering too, although largely ignored.

Consider this: according to the latest update from The initiative on GHG accounting of war, published on 24 February this year, the Russian-Ukrainian conflict has emitted 30 % more climate-changing greenhouse gases over the 3rd year of war than during the 2nd year of war, or an extra 55 million tons of CO2 equivalent. Those GHG emissions are caused by warfare, buildings reconstruction, landscape fires (in sharp increase also due to drought), damages to energy infrastructure and civil aviation displacement. The 3 years of war have generated in total 230 million tons of CO2 equivalent, the equivalent of the annual emissions of 120 million fossil fuel cars. 

In addition to active wars – Ukraine, Middle East, the Democratic Republic of the Congo to name just a few – the current geopolitical climate is clearly conducive to:

• Raw military confrontation between states, or the heightened risk of that, leading to arms races,
• A spectacular weakening of multilateral processes, and in fact a loss of trust in peaceful conflict resolution,
• A rise of authoritarian, often stridently populist, anti-woke and anti-environment political parties or states,
• And a severe backlash against climate and environmental action and regulation.

In this context, it is key to understand the climate cost of war and take that knowledge on board to influence the fight against those additional, powerful headwinds.

What is the climate cost of war?  

Wars and military preparations have profound and often overlooked consequences for the environment and global climate. In the context of escalating geopolitical tensions, these environmental impacts are becoming more severe. Conflicts and defence investments exacerbate environmental degradation and climate change, while global warming appears relegated to a distant priority.

Environmental Damage from Wars

Wars leave an indelible mark on ecosystems. Explosions release toxic chemicals like lead, mercury, and depleted uranium into the air, soil, and water. These pollutants persist for decades, contaminating agricultural land and water sources, as seen in Ukraine where 12,000 square kilometres of nature reserves have been devastated. Additionally, bombings destroy natural habitats, disrupt wildlife, and contribute to biodiversity loss.

The Russia-Ukraine war exemplifies the environmental toll of modern conflict. In its first year alone, the war generated more greenhouse gas (GHG) emissions than some entire countries, such as the Czech Republic. Fires, explosions, and the destruction of infrastructure released 120 million tons of CO₂ equivalent within the first 12 months—also comparable to Belgium’s annual emissions. Reconstruction efforts will further amplify emissions due to energy-intensive rebuilding processes.

Marine ecosystems also suffer. For instance, chemical pollution in the Black Sea caused by the war has endangered marine life. Landmines and unexploded ordnance further hinder land regeneration and agricultural recovery long after conflicts end.

Military Emissions and Climate Change

Militaries are among the largest institutional contributors to greenhouse gas emissions. If considered a country, the U.S. military alone would rank as the 47th largest emitter globally, and only taking into account the emission from fuel usage. The production of weapons and equipment also generates significant emissions.

Wars disrupt climate action by diverting resources toward defence spending instead of sustainability initiatives or renewable energy. For example, conflicts often trigger energy shortages that lead to increased reliance on fossil fuels, undermining global climate agreements like the Paris Agreement on climate change.

Geopolitical Shifts Driving Defence Spending

In response to heightened security concerns—largely driven by Russia’s invasion of Ukraine—European nations have significantly expanded their military budgets. Defence spending in the EU reached €326 billion in 2024, marking a 30% increase since 2021. This surge reflects a broader trend of prioritizing defence over climate investments, only accelerated by recent & dramatic foreign policy turn-about’s in the U.S.

Generally, geopolitical shifts have reignited an arms race that diverts attention from pressing climate challenges. The renewed focus on militarization places global warming on the back burner. Resources that could fund renewable energy projects or climate adaptation measures are instead funnelled into weapons development and procurement. For example:

• Over 80% of EU defence investments in 2023 were allocated to new military equipment rather than sustainable technologies.
• Rebuilding war-torn regions will require massive energy inputs, further delaying progress toward net-zero emissions targets.

This dynamic creates a vicious cycle: wars worsen climate change through emissions and environmental destruction while climate change itself exacerbates resource conflicts.

Realisation Leads to Action

As expressed in a recent New York Times opinion piece, “Much of the recent science sees the roots of the climate crisis in transformative technologies and their concurrent phases of capitalism: the plantation, the steam engine, late 20th-century globalization. But there has been surprisingly little said of late about the centrality of war in the narrative of global environmental threats.”

Taking into account this overlooked reality, and as nations prepare for potential future conflicts, there is an urgent need to address the environmental costs of militarization. To be sure, the best scenario would clearly be a restauration of trust, multilateralism and arms control. Very sadly, this is currently just wishful thinking; possible policies in the current arms race context include:

• Reduce Military Emissions: Transitioning military operations toward renewable energy sources could significantly cut emissions, additionally decreasing the reliance on external fossil fuels providers,
• Prioritize Climate in Geopolitical Strategy: Governments must balance security concerns with commitments to climate action. This is made much more challenging by ballooning budget deficits, but immediate risks cannot blind us to massive longer-term ones,
• Green Reconstruction Efforts: Post-war rebuilding should incorporate sustainable practices to minimize long-term environmental damage.

One would of course wish that geopolitical tensions get controlled and resolved, but they will continue to overshadow climate priorities in the foreseeable future. However, reducing them to the maximum possible extent, and considering the climate and environmental cost of war, are imperative for citizens and leaders alike. Failing to resist and tame those ill winds will leave future generations to bear the brunt of both conflict-induced destruction and unchecked global warming.

The impact of war on climate can no longer be ignored. If you want to keep up to date with more analysis on geopolitics, sustainability and the future of the planet, subscribe to our newsletter and stay tuned.