Icebergs float in a fjord after calving off from glaciers on the Greenland ice sheet in southeastern Greenland, Aug. 3, 2017 (AP file photo by David Goldman).

The global environmental crisis, encompassing runaway climate change, collapsing biodiversity and the slow death of the world’s oceans, has exposed the limitations of traditional political realism as a guide to statecraft in the 21st century. The time has come for the nations of the world to embrace a new approach to world politics that treats the preservation of the biosphere as a core national interest and a central objective of national security policy. Call this new mindset ecological realism. Political realism, which has long dominated the teaching and practice of foreign policy, including in the United States, is a venerable […]