Environmental Protection Agency Chief Scott Pruitt made headlines last week when he denied that carbon dioxide is a primary contributor to climate change.

But according to national security expert Juliette Kayyem, changing tides inside the EPA endanger more than just the ice caps: they might affect the military.

Contrasting Pruitt's comments, Kayyem referenced affirmation by Defense Secretary James “Mad Dog” Mattis that climate change is a threat; Mattis testified after his confirmation hearing that changing temperatures are a national security issue.

“Mattis is right,” Kayyem said. “Countries go to war over the fight for resources. It generally comes down to that ... one worry is that you’ll get more conflicts as natural resources get eviscerated by climate change.”

She also pointed out how people displaced by extreme weather and coastal flooding will pose a challenge to the military.

“Just look at the movement of people, refugees — climate change or extreme weather that’s going to lead to mass migrations,” she said. "[Look at] Boston and New York and other cities on the Eastern shoreline that are going to be wiped away if we don’t do something serious about resiliency and climate change adaptation on the local and state level.”

Mattis, in his testimony, implied a sense of urgency about climate change: “Climate change is impacting stability in areas of the world where our troops are operating today,” he wrote.

Kayyem agreed, saying movement in the short term could prevent undue pressures later on.

“These [decisions] will have long term consequences for the military,” said Kayyem.

Juliette Kayyem is a homeland security expert, the founder of Kayyem Solutions and host of The SCIF podcast. To hear her interview in its entirety, click on the audio link above.