Some members of Congress have recently tried to play the gotcha game, pressing witnesses to answer whether climate change is as serious a national security threat as other traditional issues. In one Armed Services Committee hearing, Navy Secretary Carlos Del Toro was asked whether climate change was more of a threat than “Communist China” or “nuclear annihilation.” Meanwhile, in a hearing before the Senate Budget Committee last month, I was pressed to pick either climate change or the national debt as the greater risk to the United States.
My answer? We’ve got to be able to walk and chew gum at the same time. An either/or mindset is the wrong way to think about climate change and national security. The security landscape of the 21st century requires us to understand how climate hazards exacerbate existing risks, and how they inhibit U.S. progress and military readiness.
Senators don’t have to take my word for it. In 2017, Jim Mattis—retired Marine general and President Trump’s first defense secretary—told Congress, “Climate change can be a driver of instability and the Department of Defense must pay attention to potential adverse impacts generated by this phenomenon.”
Many of those adverse impacts are increasing here at home, requiring greater attention from the military. In the past two years alone, U.S. troops have deployed domestically more than 70 times in response to climate-related hazards, fighting fires, rescuing citizens from floods, or delivering water. The U.S. National Guard’s time spent fighting wildfires increased from 14,000 personnel days in 2016 to 176,000 personnel days in 2021, and this demand is almost certain to grow as temperatures rise. Given the National Guard’s role in wartime, a military that does not plan for the impact of climate change on domestic demand for Guard services is one that is unprepared for combat abroad.
Of course, the security threat of climate change extends beyond U.S. borders. Take the Indo-Pacific. In criticizing Secretary Del Toro, Sen. Dan Sullivan, R-Alaska, claimed that climate change distracts from the real threat in the Indo-Pacific: China. He argues that matching China ship for ship should be the top priority for the Navy, full stop. Yet suppose the United States invests billions in new ships without accounting for extreme weather and climate resilience. The performance of such ships will suffer, and here’s why. Many Navy ships rely on cold seawater to cool their engines. Yet last year, ocean temperatures were the hottest on record, with temperatures in the northern Pacific well above normal. A retired UK general has warned that Royal Navy captains say their ship engines “have the potential to cut out with the surface sea temperature it is today, let alone at 38 to 40 degrees”—100 to 104° F.
At the same time, climate-driven extreme weather threatens U.S. military infrastructure and readiness in the Indo-Pacific. Last year, Guam was slammed by Typhoon Mawar, a category-four storm whose 150 mph winds interrupted operations at Anderson Air Force Base and caused billions of dollars of damage. This year, a massive rogue wave hit U.S. military facilities on Kwajalein Atoll, part of the Marshall Islands. Such waves are made worse by climate-driven sea level rise, and this one caused damage that the U.S. military estimated would take “months” to recover from. Both Guam and the Marshall Islands are key to maintaining U.S. power and influence in the Pacific.
Earlier this year, the State Department’s International Security Advisory Board released a report that described how climate change might affect the U.S. ability to defend Taiwan. The report’s description of how typhoons may interrupt communications capabilities or supply chain security underscores the fact that the country that plans for such disruptions based on the latest climate projections is the one that will have the upper hand. As U.S. Deputy Defense Secretary Kathleen Hicks told West Point cadets in 2023, “You can’t train, for instance, for combined operations with allies and partners if the training facilities are flooded. You can’t run an installation without water because you’re in a drought. And you can’t adequately prepare for the future threats if you’re occupied with urgent crises.”
Historian John Ross writes that when President-elect John Kennedy asked outgoing President Dwight Eisenhower why D-Day had gone so well, Eisenhower replied, “Because we had better meteorologists than the Germans!” As the United States confronts more frequent and intense extreme weather events due to climate change, more ships and guns alone will not be enough to deter and defend against the threats we face. The U.S. military must ensure it has more thoroughly considered climate change than its adversaries to keep our country safe.
