This story is from lampa nonprofit newsroom that investigates the forces impeding climate action.
Retired Marine Sergeant Vida Rivera knows that heat can be as dangerous as any enemy.
Early in her military career, she collapsed from heat exhaustion while carrying a 65-pound bag on a sweltering flight in Quantico, Virginia. Years later in Afghanistan, Rivera drove a truck in temperatures approaching 120 degrees Fahrenheit (49 degrees Celsius). But she was ready. She took a mechanics course — twice — to ensure she could fix the truck’s air conditioner if it broke.
She knew that extreme heat could cripple her Marines. “They need water and good temperatures like everyone else,” she said.
Across the US military, the climate crisis is not a distant threat. It’s a daily challenge. The ramifications of a warming planet have hit the military hard, marginalizing it More than 10,000 soldiers With heat-related illnesses since 2018, flooding bases and undermining everything from runways to nuclear preparedness.
Severe weather is hitting installations from Guam to North Carolina and creating instability in overseas areas where U.S. forces may be called upon to intervene.
For decades, the Pentagon has viewed the climate crisis as a national security threat – not for environmental reasons, but because it undermines operations and preparedness.
Now the Trump administration is dismantling this approach. Pentagon leaders have cut funding for climate research and abandoned adaptation plans. Defense Minister Pete Hegseth dismissed fears of global warming as “climate change folly”.
Critics warn that the military is forced to wander aimlessly – and that the cost may be strategic weakness in a world where climate increasingly shapes conflict.
“I think it puts our forces at risk,” said Erin Sikorsky, director of the Center for Climate and Security. “We would be less prepared if our forces were deployed to a place where it was incredibly hot and their equipment wasn’t working properly, or if they themselves were physically unable to operate… I think that’s misconduct.”
The Department of Defense did not respond to Floodlight’s requests for public documents and an interview to discuss changes to its climate policy.
The Pentagon’s 2026 budget request recommends cutting $1.6 billion in “wasteful” climate spending. Among the targeted programs: a $6 million grant to decarbonize emissions from marine vessels. It is unclear where most of the remaining cuts will come from.
It marked a sharp break from the previous administration, when the Defense Department sought $5 billion for climate initiatives in its fiscal 2024 budget — including efforts to strengthen bases against extreme weather and reduce reliance on battlefield fuels.
How rising temperatures undermine US military power
In October 2018, Hurricane Michael struck Tyndall Air Force Base in Florida with winds of 160 mph (255 km/h), flipping fighter planes over and damaging more than 600 buildings. The branch spent nearly $5 billion to repair and upgrade the base to become more resilient to future storms.
In May 2023, Typhoon Mawar struck Andersen Air Force Base on Guam with 140 mph winds and 28 inches of rain, damaging nearly 500 buildings and costing nearly $10 billion to repair and strengthen the base against future severe weather events.
According to the National Weather Service, unusually warm ocean temperatures have fueled these storms.
Rising sea levels are also expected to cause chronic flooding at coastal military bases in the coming decades, with half of coastal bases facing 270 or more flood events each year, according to the UN report. Union of Concerned Scientists.
Major storms can also hamper nuclear deterrence. Hurricanes could damage submarines or delay the transfer of nuclear warheads, warned researcher Jamie Kwong, a fellow in the Nuclear Policy Program at the Carnegie Endowment for International Peace. She said all three nuclear weapons delivery systems – air, land and water – could be hampered by climate change.
Since 2022, the U.S. military has deployed to more than 230 climate emergencies, according to the nonprofit. Center for Climate and Security. and heat-related illnesses among troops jumped 52% Between 2020 and 2024.
Much of this work has fallen to the National Guard. Over the past decade, the National Guard has spent nearly 4 million days of service responding to hurricanes, floods, wildfires and other disasters, the Pentagon said in a recent report by four Democratic US senators who requested this information.
Fort Benning has long had a problem with overheating. Spanning 182,000 hot, humid acres in west-central Georgia along the Alabama state line, this base is one of the Army’s top training centers — and has recorded more heat-related illnesses than any other U.S. military base. Until about a decade ago, someone died from heat every three years.
That crisis led to the establishment of the US Army Heat Center at Fort Benning in 2019, where military personnel are taught how to prevent and treat heat-related illnesses.
Officers there developed techniques such as arm immersion — lowering soldiers’ arms into cold water during training breaks to reduce body temperature — and ice wraps, where frozen bedsheets were wrapped around overheated soldiers to quickly lower their body temperature.
To reduce the risk of heat illness, the military generally suspends non-essential outdoor activities on extremely hot days. These “black flag” days — generally 90 degrees Fahrenheit or higher — are becoming more common, according to the 2023 report. Ministry of Defense report.
The Army may have to suspend summer training at its hottest bases and “spend a lot of money” to move that training, predicts Carolyn Baxter, a former deputy assistant secretary of defense for education and training under Joe Biden.
Military aircraft and ships are also affected. Hot, humid air means that planes have difficulty generating the lift they need. 2019 Center for Climate and Security Brief He warns that rising heat and humidity will force military aircraft to reduce their payloads – or abandon their missions entirely.
Meanwhile, warm seawater makes it difficult to cool ship engines, while melting glaciers dilute ocean salinity, which can harm sonar’s effectiveness.
Retired Army Lt. Gen. Russell Honoré, who led the military response to Hurricane Katrina in 2005, noted that drought caused by global warming helped spark the Syrian civil war and armed conflict in Sudan. He has since founded the Green Army, an organization that fights pollution in Louisiana.
“You can change your policy so that it no longer takes into account the impact of global warming on your strategic posture, but heat will destabilize global stability as well as security. It will continue to have a human impact on our daily training and operational readiness,” Honoré said.
Experts say the melting ice in the Arctic also increases the possibility of military conflict, because it opens up shipping lanes that were previously inaccessible.
“What it really means is that there is an accident waiting to happen,” according to Threat Multiplier, a book by Sherry Goodman, who led the Army’s environmental efforts during the Clinton administration as deputy undersecretary of defense.
Mission on emissions: Why the US military once took climate seriously
The Department of Defense developed its first climate change strategy in 1998, and a decade later declared global warming a national security issue. After Biden took office, the military’s focus on climate impacts has taken on new urgency.
In 2021, then-Defense Secretary Lloyd Austin called climate change an “existential threat to our nation’s security,” adding that its harms were “unavoidable.”
For the Pentagon, the climate crisis wasn’t just about the environment, it was about how and where troops could operate.
“How can I continue to do my job even though the operational environment is changing?” said John Conger, a former senior Defense Department official who later directed the Center for Climate and Security. “You don’t think about emissions, you think about missions.”
In 2022, the Army began rolling out its first hybrid tactical vehicles. Hybrid vehicles are quieter and use less fuel, which can save lives in combat.
“We were losing Marines and soldiers due to the constant movement of fuel to the front in Afghanistan and Iraq,” Goodman wrote in her book. “For every 24 fuel convoys in Afghanistan, one soldier is killed.”
New doctrine: Climate no longer matters
Donald Trump pushed to rename the Department of Defense as the “War Department.” Hegseth made it clear that the Pentagon’s priorities have changed.
“@DeptofDefense is not doing climate change crap,” he wrote in March. Share on X. “We train and fight.”
On March 17, Hegseth Banned Pentagon Agencies from spending money on climate planning, and ordered leaders to “remove all references to climate change and related topics from mission statements.” In his September 30 speech to hundreds of military leaders at Quantico, Hegseth declared that “there will be no more worship of climate change” in the military.
The Secretary’s March guidance leaves room to continue some weather-related work, including risk assessments, environmental reviews and base resilience improvements.
But the Pentagon also announced it would cancel 91 studies focused on climate and social science research. The move would save $30 million — a small portion of the department’s $850 billion budget — stymieing research on emerging security threats, including climate change, extremism and disinformation.
Climate action plans from the Army, Navy, Air Force and Coast Guard have quietly disappeared from public websites in recent months. The Pentagon also closed its climate resilience portal.
“If you don’t have complete information because you’re deliberately ignoring certain pieces of the puzzle, you put yourself at a disadvantage — because the Russians and the Chinese aren’t ignoring them,” said Conger, former director of the Center for Climate and Security.