QADIS, Afghanistan — When the temperatures plunged far below freezing in Niaz Mohammad’s village last month, the father of three struggled to keep his family warm. One particularly cold night, he piled every stick and every shrub he had collected into their small wood stove. He scavenged for trash that might burn, covered the windows with plastic tarps and held his 2-month-old son close to his chest. Ice crept across the room: It covered the windows, then the walls, then the thick red blanket wrapped around Mr. Mohammad’s wailing son. “The cold took him,” Mr. Mohammad, 30, told visiting journalists for The New York Times, describing the details of that horrible night.

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