Episode 117 examines the intersection of climate change, national security, and irregular warfare, with a particular focus on how environmental changes are reshaping global security challenges from the Arctic to the Pacific Islands. Our guests begin by exploring pivotal moments in the evolution of environmental security and its impact on national defense policy. They then discuss how climate-related changes affect military operations and strategic partnerships, particularly in the Pacific region. The conversation continues with an analysis of how both state and non-state actors leverage environmental crises in irregular warfare tactics. They conclude by offering policy recommendations for addressing climate security challenges and building resilient international partnerships. Sherri Goodman is a Senior Fellow at the Wilson Center's Environmental Change and Security Program and Polar Institute. As the former Deputy Undersecretary of Defense for Environmental Security, she coined the term "threat multiplier" to describe climate change's impact on national security. She has served on numerous advisory boards and is the author of "Threat Multiplier: Climate, Military Leadership, and the Fight for Global Security." Ambassador John Hennessey-Niland is a Professor of Practice at the Bush School of Government and Public Service. As the former U.S. Ambassador to Palau, he brings extensive experience in Pacific region affairs. His previous roles include serving as the foreign policy advisor to the Commander of U.S. Marine Corps Forces Pacific, and he has held various diplomatic positions across Europe and the Pacific, providing him with unique insights into the intersection of environmental security and irregular warfare.