Although the Office of Naval Research funded much of the early climate change research, the Defense Department successfully pushed to omit most reporting of military emissions from global climate agreements like the Kyoto Protocol.

The Defense Department knew it was the United States’ largest petroleum user and said so. It also knew that its emissions would come under scrutiny if they were known, and that pursuing preeminence was emissions-intensive and undermined global climate goals.

...

The US national security community’s approach to climate has not only been mirrored by NATO but amplified by private organizations such as the International Military Council on Climate Security, which produces an annual World Climate and Security Report. These doomsday scenarios often ignore the necessity of emissions reductions and capacity building. They are lifeboat and drawbridge approaches to security on the assumption that it is already too late.

The figures below, from the 2022 Department of Defense Climate Risk Analysis, illustrates the assessment that climate change will lead to conflict and increased demand for the military to perform humanitarian missions.

Defense Department views of climate change. Top: Examples of connections between climate hazards, primary and secondary climate impacts, and security implications. Bottom: Selected regional hazards worsened by climate change (key to symbols on the top row above map) and identified security implications (key to symbols on the bottom row below the map). This map illustrates some of the key risks by region, but is not comprehensive of all risk. (2022 Department of Defense Climate Risk Analysis)

...

The national security establishment recognizes the short-term impacts of climate change—the operational challenges, the expenses of adaptation and repair, the race for resources, and the possibility it will cause increased tension and war. This strategic and military policy response to climate change is practical in some tactical respects, but it is shortsighted and potentially counterproductive because it does not attend to Earth systems or the role of the military, military industry, and war as significant contributors to climate change.