As the world barrels toward an uncertain future, a troubling trend has emerged: military spending is skyrocketing, and with it, the planet’s carbon emissions. According to the Stockholm International Peace Research Institute (SIPRI), global military expenditures in 2024 reached a staggering $2.7 trillion—a 9.4% increase over the previous year, marking the highest year-on-year rise since the end of the Cold War. This surge, highlighted in the United Nations secretary-general’s new report, "The Security We Need: Rebalancing Military Spending for a Sustainable, Peaceful Future," is not just a matter of budgets and balance sheets. It’s a seismic shift with far-reaching consequences for climate, development, and global security.
All world regions except Africa and South America have seen substantial increases in military spending over the past decade. Most notably, NATO members—who collectively account for 55% of global military expenditures—agreed earlier this year to raise their defense spending targets from 2% of GDP to a hefty 3.5% by 2024, with an additional 1.5% earmarked for other defense-related expenditures. If these targets are met, the UN report’s authors estimate that global military expenditures could balloon to between $4.7 and $6.6 trillion by 2035, in today’s dollars.
This escalation is not happening in a vacuum. The world is currently witnessing a sharp uptick in armed conflicts, from the grinding war in Ukraine to the devastation in Gaza, as well as ongoing violence in Sudan, the Democratic Republic of the Congo, and Myanmar. Diplomacy and peacebuilding, meanwhile, have taken a back seat, with war rhetoric dominating headlines and political discourse.
But what does this mean for the broader global agenda, particularly the Sustainable Development Goals (SDGs)? Progress on these goals has been painfully slow. As of October 2025, only 35% of SDG country targets are on track or showing moderate progress, while nearly half are stagnating and 18% are actually regressing. The UN report warns that the relentless growth in military spending will likely push progress even further off course.
Some of the consequences are already visible. In 2024, official development assistance (ODA) from OECD Development Assistance Committee members fell for the first time in six years. The UK, for example, cut its ODA from 0.5% to 0.3% of gross national income in 2025, explicitly reallocating the difference to military spending. While the “guns versus butter” trade-off is not always so clear-cut, a statistical analysis cited in Defence and Peace Economics found that in lower- and middle-income countries, a 1% increase in military expenditures as a share of GDP results in a nearly equal reduction in health spending. Governments, reluctant to raise taxes or borrow more, end up crowding out social expenditures in favor of defense.
It’s not just about dollars and cents. Higher domestic arms research and development (R&D) spending siphons off science, technology, engineering, and mathematics (STEM) talent—the very expertise needed for green innovation. In countries like the UK, already grappling with STEM shortages, military R&D will only intensify competition for talent, potentially driving up costs for renewable energy projects and other green technologies.
The environmental impact of this militarization is jaw-dropping. Recent research cited by the Thomson Reuters Foundation and the Conflict and Environment Observatory estimates that military production and activity account for roughly 5.5% of all global greenhouse gas emissions—more than double the sector’s share of global GDP. Military aircraft and ships are notorious "gas guzzlers," and arms manufacturing is both carbon- and resource-intensive, relying on critical minerals whose extraction often wreaks havoc on local environments.
Armed conflicts themselves are turbocharging the climate crisis. Groundbreaking research led by climate scientist Lennard de Klerk found that the first three years of the war in Ukraine generated nearly 237 million metric tons of greenhouse gases—equivalent to putting 120 million fossil-fuel cars on the road, or the combined annual emissions of Belgium, Austria, and Ireland. The climate damage cost of the war already exceeds $43 billion, according to de Klerk. "This is pushing us in the wrong direction at a time when we drastically have to cut emissions," he told Context, a Thomson Reuters Foundation platform.
Wildfires sparked by relentless shelling have accounted for about 20% of Ukraine’s war-related emissions. Nearly 850,000 hectares burned in 2024 alone—more than 20 times the annual average—a figure exacerbated by climate change-induced dryness. Similar patterns have been observed in Gaza, where missile strikes have ignited fires, destroying forests and farmland. In both Ukraine and Gaza, the destruction of energy infrastructure has released potent greenhouse gases, including methane and sulfur hexafluoride, which has a global warming potential 24,000 times greater than CO2.
Reconstruction, too, is a climate risk multiplier. In Gaza, more than 90% of housing has been destroyed, creating 60 million tons of debris, according to UN estimates. Rebuilding will require massive amounts of concrete and steel, both highly carbon-intensive materials. Benjamin Neimark, a senior lecturer at Queen Mary University of London, said, "The carbon footprint of post-war reconstruction in Gaza will dwarf emissions from the conflict itself." The destruction of farmland and shrubland also raises the specter of desertification in a region already vulnerable to climate change.
These wars don’t just raise emissions at the frontlines. Airspace closures have forced commercial flights to reroute, increasing fuel consumption. For example, flights from London to Tokyo now take almost three hours longer, according to de Klerk. Unrest in the Middle East has disrupted shipping through the Red Sea, pushing vessels onto longer, more emission-intensive routes.
Despite the massive climate footprint of militaries, countries are not required to report military emissions to international climate bodies. "We can’t start making meaningful cuts without adequate baselines," Neimark said. "The military has long operated as if the emissions coming out of an F-35 don’t stink, and that has to stop." With many countries ramping up defense spending, experts worry that military emissions will continue to rise unchecked, diverting much-needed funding from climate action.
Even as NATO’s new 3.5% defense spending target is justified as a response to Russia’s invasion of Ukraine and other perceived threats, critics argue it is more a political gesture than a strategic necessity. Achieving this target would require an additional $474 billion annually compared to 2024, adding 17.4% to global military expenditures and an estimated 132 million tons of additional carbon emissions each year. While some politicians warn of a high probability of a full-scale Russian attack on European NATO members within the next five years, others, including senior Western intelligence officials, point out that Russia’s military has already been stretched thin in Ukraine.
Ultimately, the relentless rise in military spending risks fueling an ever-accelerating global arms race, diverting resources from social spending, development aid, and crucial climate finance. As the UN report and climate researchers alike warn, unless all major powers—including the US, Russia, and China—change course, the world risks undermining not only its security but also its hopes for sustainable development and a livable climate.
The stakes could hardly be higher, and the clock is ticking.
