For four decades, the Pacific coast of Panama has counted on a reliable seasonal pulse of cold, nutrient-rich water that powers local fisheries and cools coral reefs. In early 2025 that pulse all but vanished. Scientists report that the Gulf of Panama’s usual upwelling failed for the first time in the instrumental record, a breakdown they see as a warning about how quickly climate disruption can unsettle tropical seas. During most years from roughly December to April, strong northerly trade winds sweep across Central America and into the Gulf of Panama. Those winds push aside warm surface waters so that...