Each year, along the peaceful coasts of Panama, an essential oceanographic phenomenon occurs: upwelling. This process brings up to the surface of deep, cold and rich nutrients, supporting the productivity of local peaches and protecting coral reefs from overheating. Until 2025, this seasonal cycle seemed as reliable as the return of the seasons. But this year, for the first time in at least four decades, no rise in cold water took place in the Gulf of Panama.
The vital role of upwelling in the Gulf of Panama
Upwelling is a fundamental oceanographic phenomenon for coastal tropical ecosystems. In the Gulf of Panama, it manifests itself each year during the dry season, between December and April. This process is the result of the action of the Northern Alizés winds. They cause a divergence of surface waters, allowing deep, cold and rich nutrient waters, to rise to the surface. This ascent nourishes phytoplankton, at the base of the marine food chain.
According to Aaron O'Dea, paleobiologist at the Tropical Smithsonian Research Institute (STA), this system works as “a natural ocean fertilization engine”. It allows the development of abundant fisheries. In addition, he plays a thermal stamp role for coral reefs during hot weather.
© Aaron O'DeaVery low chlorophyll around Panama in February 2025, signaling the absence of upwelling for the first time in 40 years.
Unlike major upwelling systems like those of Humboldt or California, that of Panama remains little studied. However, it remains just as crucial. The effect of upwelling is not limited to biological productivity. Indeed, it also influences the coastal microclimate, refreshing the bathing waters during the tourist period and regulating local temperatures.
For at least forty years, this seasonal cycle has been repeated regularly. There was a measurable drop in surface temperatures and an increase in concentration in chlorophyll A, a key marker of phytoplanktonic production. Satellite surveys and sea campaigns have confirmed it year after year. Panama was counting on this oceanic stability. Until in 2025, the cycle was interrupted for the first time, opening a new chapter of environmental uncertainty for the region.
A brutal failure linked to the disruption of the winds
At the beginning of 2025, the researchers therefore noted a major anomaly: classic upwelling indicators were absent. No significant temperature drop on the surface, no increase in chlorophyll, and a nutrient deficit measured in the water column. The team quickly identified the main factor: an unprecedented weakening of the Northern Alizés.
These winds, physical engines of the upwelling process, were abnormally weak and irregular at the start of the year. This atmospheric disturbance prevented the formation of the pressure gradient necessary for the uprising of deep waters. Data collected by the S/Y Eugen Seibold research vessel, equipped with advanced weather sensors, confirmed the absence of vertical dynamics in the area concerned.
Andrew Sellers, climatologist, and Carlos Pérez-Medina, a specialist in Air-Mer interactions, evokes several tracks in a press release to explain this deregulation. Either natural variability on a ten -year scale, such as the Pacific Decadal Oscillation, or the influence of anthropic climate change. By modifying the structure of tropical winds, these phenomena reduce the frequency and intensity of the conditions conducive to upwelling.
Atmospheric simulations show a correlation between the weakening of the trade winds and pressure anomalies in the East Pacific. These observations suggest that this is not a simple meteorological accident. But the result of a shift in climatic balances. This atmospheric rupture may not be isolated. Other tropical regions could undergo the same fate, exposing whole sections of biodiversity and coastal savings to increasing instability.
Immediate and disturbing ecological consequences
In fact, the abolition of upwelling in 2025 has not only changed the water column in the Gulf of Panama. It sparked a cascade of worrying ecological effects. In the absence of nutrients, phytoplankton has not proliferated as usual. This primary productivity deficit then affected the entire marine food chain.
© Aaron O'Dea
Chlorophyll concentrations in the oceans around Panama (blue = weak, red = high) in February 2024, showing a productivity peak in the Gulf of Panama during a period of typical water rise.
The artisanal fisheries, which target species such as mackerel, sardine and certain cephalopods, have seen their yields drop significantly. For many Panamanian coastal communities, this drop in stock means significant economic losses, in a period already tense by the effects of warming.
But the effects do not stop at peaches. The coral reefs, usually “cooled” by upwelling during the dry season, found themselves exposed to high temperatures. This has favored whitening phenomena. As Andrew Sellers reminds us, ” Without upwelling, corals lose their only natural protection against seasonal thermal stress ».
The study also highlights the increased risk of proliferation of pathogens in these warmer and less oxygenated waters, more weakening benthic fauna and sensitive recipe species. Ultimately, these disturbances can cause imbalances in trophic networks, even localized collapses of sea populations.
Researchers do not exclude that certain ecosystems do not rely. And if such events should be repeated, the whole of tropical coastal ecological stability would be at stake. With chain repercussions to the regional blue economy.
An alert on failing surveillance of the tropics
Despite the strategic importance of tropical systems like that of Panama, the scientific surveillance of these regions remains very limited. Unlike the great currents of temperate upwelling, well mapped and integrated into global models since the 1970s, the equatorial areas are sorely lacking in high frequency data.
The case of 2025 highlights a dead angle of global climate monitoring. The researchers therefore insist on the urgency to extend the Oceano-Climatic observation networks in tropical basins. “” If this event had not been captured by our campaign on S/Y Eugen Seibold, it would have gone unnoticed “, Underlines Hanno A. Slagter, co-author of the study.
Existing climatic models cannot detect or anticipate this type of rupture without a solid database. The 2025 study combined satellite data, in situ measures, chemical analyzes, temperature profiles and atmospheric simulations coupled to reconstruct the mechanisms. This approach must become the norm in tropical areas. The absence of regular monitoring deprives coastal states of early alert tools. The latter remain essential to adapt the management of peaches, anticipate the risks for corals or prevent food shortages.
The authors call for reinforced international support for research in the tropics, in particular via interinstitutional programs. The Panamanian event cannot be treated as an isolated anomaly. It marks a critical limit of our ability to understand and manage the regional effects of climate change.
With an unwavering passion for local news, Christopher leads our editorial team with integrity and dedication. With over 20 years’ experience, he is the backbone of Wouldsayso, ensuring that we stay true to our mission to inform.
