A string of climate-related disasters that crippled the strategic capability of multiple U.S military bases in recent years has exposed the military's vulnerability to extreme weather, putting a spotlight on its failure to prepare and the consequences to national security.
Offutt Air Force base in Nebraska, home to the U.S. Strategic Command, was incapacitated by historic flooding that swept through the Midwest in March. More than 130 structures were destroyed, and the cost of rebuilding has hit $1 billion and could go higher.
Hurricane Michael, a monster Category 5 storm, wiped out Tyndall Air Force Base in Florida in 2018, damaging 17 grounded F-22 stealth fighters and causing an estimated $5 billion in damage. Heat illnesses in the military are also rising, putting service members' lives at risk, a 2019 investigation by InsideClimate News and NBC News showed.
Yet the Defense Department, now facing a presidential administration that rejects science and ignores climate risks, has been slow to respond, and that's raising concerns across the military and from Congress's watchdog agency and military think tanks. In a series of reports this year, they questioned the military's readiness, offering foreboding conclusions that climate change poses significant threats to national security, military preparedness and personnel safety—threats they say the military is not fully equipped to handle.

"The Department of Defense is precariously underprepared for the national security implications of climate change-induced global security challenges," a U.S. Army War College study bluntly concluded.
The projections are also worrisome for U.S. military operations overseas, where armed forces face extreme weather, sea level rise and the risk that diminishing water supplies, changing disease patterns or crop failures could destabilize a country, the Government Accountability Office wrote in a recent report to Congress.
The reports stress the need for massive military infrastructure safeguards. They also highlight concerns that some sectors of the Department of Defense remain resistant to climate change projections; have failed to take steps to mitigate its effects; and are unprepared for the consequences.
"It seems apparent from those of us on the outside that the level of preparedness doesn't match the level of risk," said Alice Hill, a National Security Council advisor during the Obama administration who specializes in global risks. 
The military had a clear picture a decade ago of the threats posed by climate change, she said.
"It's not like we've been caught unawares," said Hill. "It's not to say no efforts are underway, but are they enough? There is concern they are not sufficient given how quickly climate is changing."
The undercurrent in these reports suggests the Pentagon and Congress are reacting to climate change without comprehensive preparation at a time that demands broader strategies be incorporated into climate planning.
The reports are especially striking given the Trump administration's record of climate science denial and its disregard of the consequences of environmental policy rollbacks. The War College report said the government was "perceived to be an irresponsible actor in the global environment," citing President Donald Trump's decision to withdraw from the Paris climate accord as an example.
Senior military leaders have testified to Congress that the Defense Department recognizes the risks from climate change. Still, adaptation is slow in coming, said John Conger, director of the Center for Climate and Security and a former assistant secretary of defense for Energy, Installations and Environment.
"The DOD is a large organization," he said. "You can't change its direction quickly."
That turn becomes even more sluggish given the anti-climate posture taken by the Trump administration.
"There is a reticence to take on the White House overtly," he said. "(Military) leaders won't omit climate change in their planning calculations. They will move slowly and systematically in the right direction."
Map: Pentagon Report on Military Bases and Climate Risk
​
Although the Defense Department identified climate change as a threat to its operations and installations in 2010, the agency remains largely paralyzed when it comes to designing a comprehensive strategy addressing the effects of a changing climate as a national security issue with potential impacts to the department's missions, operational plans, and installations, according to the GAO.
The GAO found that the Defense Department's assessment of extreme weather and climate change risks relied on past experience rather than an analysis of future vulnerabilities based on climate projections. The department's designs for new construction also generally failed to consider climate projections, it said.
For example, the study found that eight of 23 bases reviewed had not considered climate projections in base master plans, including Joint Base Pearl Harbor-Hickam in Hawaii, which faces tropical storms and sea level rise.
The agency made eight recommendations—among them, that the armed forces update guidelines to include climate-risk analysis in master plans and guidance on how installations can make use of climate projections when they prepare such plans.
The Defense Department, in its formal response to the report, agreed with all the recommendations. "The Department will continue to tailor additional sources of climate projection data to other planning requirements, and integrate these projections into our criteria as appropriate," it said.
In its own report to Congress earlier this year, the Defense Department identified 79 military bases that face significant threats from climate change. It acknowledged that climate change is a national security issue and said the department "must be able to adapt current and future operations" to this new reality.

Damage Reverberates Well Beyond a Single Base

When a military facility is wrecked by a climate disaster, the consequences go far beyond the damage to physical structure, said Jon Powers, a retired Army captain who served as special advisor on energy in the Office of the Assistant Secretary of the Army during the Obama Administration and is now president of CleanCapital, a company that directs investment in clean energy generation.
"The operations that are coordinated from that facility are halted," said Powers. "The consequences are not just to the facility, but to the operational readiness of the units being supported out of that building."
If a communication center in the U.S. is knocked out of commission, for example, the disruption could be to military operations half-way around the world.
"These facilities have to be designed for lifetimes of 50 years or more," he said. "If we are going to make major investments in facilities, we have to make sure they are protected for their lifetime."
Service members also face new risks in a warming world, even on U.S. soil. InsideClimate News' investigation with NBC News this year found that cases of heat stroke or heat exhaustion among U.S. troops were up 60 percent over the past decade, as preventable heath deaths continue, with cascading consequences for military readiness.
Chart: The Rising Danger from Heat
In a study spawned by our reporting, the Union of Concerned Scientists calculated that by mid-century, military personnel at U.S. bases in the Lower 48 states could face an extra month on average of potentially deadly heat days if the greenhouse gas emissions driving global warming continues at a high rate.
Aircraft also struggle to perform as heat and humidity rise, and that's having an effect already, the Center for Climate and Security found. Consequently the current fleet of military aircraft inventory might not be fit to operate in a future with high temperatures.

Threat Multipliers

Globally, the military should prepare for new foreign interventions, including humanitarian supply missions and disaster relief, triggered by climate-related impacts, the Army War College report warned.
It examined the ripple effects of climate change-induced stressors, such as availability of water, declining food production, populations displaced by sea level rise and regions made uninhabitable because of excessive heat. These stressors can tax already weak nations with unstable governments and disrupt civil society, potentially lighting the fuse on conflict, like what happened in the Syrian civil war.
The report, which focuses on the Army, pointedly says the military must consider changes in doctrine, organization, equipment, and training to meet the mounting threats of climate change.
"It would be shortsighted for any organization to not consider how potential future changes might impact their operations," said Col. Parker L. Frawley, an assistant professor in the Department of National Security and Strategy at the United States Army War College.
The Arctic is an example. As Arctic sea ice continues to decrease, there are greater opportunities for countries to take advantage of new shipping routes. Russia and China have embarked on a rapid build-up in the Arctic to claim control over polar trade routes, with Russia currently planning to open 10 search-and-rescue stations, 16 deep water ports, 13 airfields and 10 air defense sites.
"These developments create not only security outposts for Russia, but also threats to the U.S. mainland," the report says.
"Steps taken now can put the Army on a path to lead the nation in preparedness and environmental awareness," the report says.  "Alternatively, the Army can continue its present trajectories, ignoring the myriad existing and potential threats that result from climate change and environmental concerns more broadly, including alienation of youth, allies and voters on whose largesse it depends, hurtling through the night in the belief that it is as unsinkable as the Titanic."
Top photo: Tyndall Air Force Base in Florida was heavily damaged when Hurricane Michael hit in 2018 as a powerful Category 5 storm. Several stealth fighter jets were at the base for maintenance at the time and couldn't be moved out in time. Credit: Airman 1st Class Kelly Walker/U.S Air Force