Yale 360: Phan Dinh Duc leans against yellow sacks of freshly harvested rice. Its a warm spring evening in Vietnams Mekong Delta, and Duc, a local farmer, is waiting for traders to arrive by truck to purchase his produce and sell it on commodities markets. Beyond him lies a vast checkerboard of rice paddies, each filled with water and bordered by a network of canals and roughly 10-foot-high earthen dikes. They enable year-round rice cultivation in an area where, a half century ago, vast floodplains typically...