For more than four decades, along Panama’s Pacific coast, the ocean has followed a precise and reliable rhythm. Between January and April, cold, nutrient-rich waters rose from the deep, feeding the marine food chain and protecting coral reefs and local fisheries. In 2025, however, this mechanism suddenly stopped. The Panama upwelling did not occur, leaving scientists with no historical precedent to cling to and opening disturbing questions about the stability of tropical ocean systems.
The phenomenon was documented almost live thanks to a scientific expedition already active in the region. Measurements collected in early 2025 showed a clear anomaly: no rising cold water, consistently high surface temperatures, and the absence of the usual increase in nutrients. An event which, according to available data, had never been recorded before in the observation series that began over 40 years ago.
Normally, northern trade winds push surface water offshore, allowing deep water to surface. This process supports the growth of phytoplankton, the basis of the entire marine ecosystem. In 2025, however, the sea remained unusually warm and “silent”, depriving the ocean of its usual biological engine.
Weakened winds, less nutrients
At the basis of the collapse of the Panama upwelling was an anomalous weakening of the trade winds. Without the necessary atmospheric buoyancy, the water column did not mix and nutrients remained trapped at depth. Satellite observations have confirmed exceptionally low chlorophyll levels in the Gulf of Panama right around the time marine productivity is expected to peak.
The consequences did not take long to manifest themselves. Sardines, mackerel and squid, key species for artisanal and commercial fishing, have shown signs of decline. Coastal communities are already experiencing declines in catches, while the overall economic impact is still being assessed. Coral reefs have also suffered strong thermal stress: without the usual cooling guaranteed by upwelling, the conditions favorable for coral bleaching have increased significantly.
The study that certified the event, published on Proceedings of the National Academy of Sciencesis based on data collected aboard the research vessel S/Y Eugen Seibold, jointly operated by the Smithsonian Tropical Research Institute and the Max Planck Institute. Researchers openly speak of the complete disappearance of the upwelling mechanism, a fact that eliminates one of the main elements of stability of the local marine ecosystem.
An event that risked going unnoticed
One of the most critical aspects that emerged concerns the poor coverage of monitoring systems in tropical regions. If the expedition had not been scheduled at that time, the collapse of the Panama upwelling might have gone undetected. Unlike currents such as the Humboldt or California currents, which are constantly observed, tropical areas often depend on sporadic campaigns.
According to the researchers, this lack of data creates dangerous blind spots in understanding global ocean variability. The Smithsonian Institute itself defined the episode as a clear example of the climate vulnerability of tropical oceans, where even small atmospheric changes can produce enormous ecological effects.
Sign of a systemic change or simple anomaly?
The crucial question remains open: is what happened in 2025 an isolated event or the first wake-up call for a deeper transformation? Scientists hypothesize two main scenarios. On the one hand, a natural variability linked to multi-year climate cycles such as the Pacific Decadal Oscillation. On the other hand, the influence of anthropogenic climate change, which could permanently alter tropical wind regimes.
Atmospheric models indicate a correlation between weaker winds and new pressure patterns over the eastern Pacific Ocean. However, without a continuous, high-resolution observation network, detecting early signals or exceeding critical thresholds remains extremely difficult. The Panama upwelling, taken for granted for decades, today appears as a fragile balance that may no longer be guaranteed.
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