What’s behind Donald Trump’s obsession with Greenland? 

Most of the island is covered in ice, less than sixty thousand people live there and, until recently, it was best known for snowy photos of polar bears. But climate change has changed the equation and thrust the island into the middle of global politics. 

Donald Trump has repeatedly said he’d like to buy the territory, and last week at a news conference he said that taking military action to acquire it was not off the table. 

Sherri Goodman is secretary general of the International Military Council on Climate and Security. She is also a senior fellow at the Wilson Center and author of a new book, “Threat Multiplier: Climate, Military Leadership, and the Fight for Global Security.”