Professor David Titley (see also, and here) writes in the online newsletter DefenseOne:

Many observers think climate change deserves more attention. They might be surprised to learn that U.S. military leaders and defense planners agree. The armed forces have been studying climate change for years from a perspective that rarely is mentioned in the news: as a national security threat. And they agree that it poses serious risks.

I spent 32 years as a meteorologist in the U.S. Navy, where I initiated and led the Navy’s Task Force on Climate Change. Here is how military planners see this issue: We know that the climate is changing, we know why it’s changing and we understand that change will have large impacts on our national security. Yet as a nation we still only begrudgingly take precautions.

Note the advisory board at The Center for Climate & Security. Along with WHOI‘s Rear Admiral (ret.) Richard F Pittenger, Professor Titley one of many people in the U.S. national security establishment who are very worried about the effects of climate disruption, its implications for the readiness and infrastructure of the U.S. military, and its implications for U.S. strategic security, especially in places like the Arctic.

True, the Pentagon is a major emissions generator, and that will need to be dealt with. But the emissions from U.S. natural gas use dwarf those of the U.S. military many times. In 2015, these were 1.5 GtCO2. For all energy uses, they were about 5.8 GtCO2. I reserve the term liberal climate deniers for people who, while they supposedly accept climate change, it’s human causes, and the mitigation necessary at face value, refuse to do the proper triage to see what needs to be reduced the most, and exploit the cause to further their own political agendas. That doesn’t help to fix the problem, and all engineering fixes involve tradeoffs.

See also the independent assessment on implications for U.S. national security of climate change.