As the current Administration winds down, each of the President’s Cabinet members have submitted “Exit Memos” detailing “the progress we’ve made, their vision for the country’s future, and the work that remains in order to achieve that vision.” They are all worth a read. Of particular note is Secretary of Defense Ashton “Ash” Carter’s memo, and how it contextualizes the risks and opportunities associated with a changing climate. Despite perceptions to the contrary, Secretary Carter joins a growing list of defense leaders, civilian and military, stretching back to the early years of the George W. Bush Administration, that have taken climate change seriously as both a matter of national security, and a driver of innovative action.

First, it’s worth quoting in full Secretary Carter’s characterization of the new geostrategic landscape, as it’s important context for how many defense practitioners view a changing climate:

We don’t have the luxury of choosing among these challenges — we have to address them all. At the same time, we must contend with an uncertain future — ensuring that we continue to be ready for challenges we may not anticipate. America is today the world’s foremost leader, partner, and underwriter of stability and security in every region across the globe, as we have been since the end of World War II. But even as we continue to fulfill this enduring role, it’s also evident that we’re entering a new strategic era. Today’s security environment is dramatically different — more diverse and complex in the scope of its challenges — than the one we’ve been engaged with for the last 25 years, and it requires new ways of thinking and new ways of acting. As the world changes and complexity increases, we’ll have to change, too — how we invest, how we fight, how we operate as an organization, how we attract and nourish talent, and how we balance risk across the many competing threats the Department faces.

This “more diverse and complex” security environment is made even more complex by the addition of the disruptive element of a rapidly-changing climate, which is already starting to alter the physical underpinnings of that security environment – the food, water, energy and critical infrastructure systems that sustain the existing international order, and shape what the U.S. Department of Defense (DoD) does, or does not, do. From Secretary Carter’s memo:

The Department published a Climate Change Adaptation Roadmap, focused on acknowledging and managing the risks inherent in climate change — both its nature as an instability accelerant in many parts of the world and the danger it poses to our own enterprise such as sea-level rise and flooding at coastal bases or drought in the southwest. As described in the President’s memorandum on Climate Change and National Security, the impacts of climate change may increase the frequency, scale, and complexity of future missions, including defense support to civil authorities, while at the same time undermining the capacity of our domestic installations to support training activities. Our actions to increase energy and water security, including investments in energy efficiency, new technologies, and renewable energy sources, will increase the resiliency of our installations and help mitigate these effects. Already, the Department has reduced energy usage at contingency bases by 30 percent, is on track to meet its commitment of 3 gigawatts of renewable energy purchases at our bases by 2025, and has executed more than $1.8 billion in Energy Savings Performance Contracts.

The long and short of that is: Climate change makes it more difficult for the DoD to do its job. Phenomena such as sea level rise and extreme droughts and floods seriously complicate an already over-complicated security environment – one that gets more and more complicated every year (due to all sorts of growing risks to global stability, ranging from cyber-attacks to the mass displacement of peoples). There’s nothing political or partisan about that assessment. As noted earlier, it’s something the DoD and the intelligence community have been concerned about for decades.

However, as Secretary Carter implies, if the DoD is given the support it needs to adapt to these climatic changes, including through building a more climate-resilient military infrastructure, and investing in advanced energy to make the DoD a more capable warfighter and disaster responder, that more complex security environment can become a less overwhelming obstacle. Indeed, that complexity can be a springboard for new opportunities in defense- including opportunities to enhance military effectiveness, while also building the resilience of those civilian communities and sectors that support our military, both directly and indirectly. Dealing with climate change risks through the long-term planning lens of the DoD also opens up significant opportunities for conflict prevention, and the avoidance of future humanitarian crises.

Frankly, a new Defense Secretary under a new Administration will have no choice but to deal with the national security implications of climate change. That ship has sailed. But dealing with it doesn’t have to be a subtractive exercise. The exercise can be profoundly additive in helping the DoD become a better fighting force, and in turn, making the United States a more secure and prosperous place.