The farmer stood in his patch of forlorn coffee plants, their leaves sick and wilted, the next harvest in doubt. Last year, two of his brothers and a sister, desperate to find a better way to survive, abandoned their small coffee farms in this mountainous part of Honduras and migrated north, eventually sneaking into the United States. Then in February, the farmer’s 16-year-old son also headed north, ignoring the family’s pleas to stay. The challenges of agricultural life in Honduras have always been mighty, from poverty and a neglectful government to the swings of international commodity prices. But farmers, agricultural scientists and industry officials say a new threat has been ruining harvests, upending lives and adding to the surge of families migrating to the United States: climate change. And their worries are increasingly shared by climate scientists as well. […]