Panama Pacific Upwelling Failure of 2025
In 2025 the seasonal upwelling in Panama's Pacific Gulf failed for the first time in 40 years of continuous monitoring, arriving 42 days late, lasting only 12 days instead of 66, and reaching a minimum sea surface temperature of 23.3°C instead of the typical 19°C.
A PNAS study by Aaron O'Dea and colleagues at the Smithsonian Tropical Research Institute (STRI) documented an unprecedented collapse of the seasonal upwelling cycle in the Gulf of Panama during 2025. For roughly 40 years of instrumental records (since approximately 1985), the upwelling has been one of the most reliable features of the regional ocean climate. The historical baseline cycle starts around January 20, persists for 66 days, and cools surface waters to a minimum of approximately 19°C, with extreme cold events reaching 14.9°C. In 2025, sea surface temperature did not drop below 25°C until March 4 — 42 days later than normal. The cool period persisted only 12 days, an 82% reduction from the historical norm. The minimum sea surface temperature reached just 23.3°C, roughly 4°C warmer than typical. The cycle normally pulls cold, nutrient-rich water from depth toward the surface, fueling plankton blooms, fish productivity, and a thermal cooling effect that protects inshore Coral Reefs during the hot dry season. The 2025 failure removed this cooling refuge during the most thermally stressful months of the year. The study was published in the Proceedings of the National Academy of Sciences (DOI 10.1073/pnas.2512056122). STRI has continuously monitored the Gulf of Panama since the 1980s and has operated in Panama since 1923, giving the dataset rare longitudinal depth for a tropical ocean system.