For the first time in at least 40 years of systematic records, the Gulf of Panama’s “seasonal upwelling” (the mechanism that pushes cold, nutrient-rich water from the bottom to the surface every first quarter of the year) collapsed in 2025.
2026, fortunately, is not repeating the pattern. But what researchers are discovering is no more reassuring.
Has the outcrop “gone”? Not exactly: it didn’t completely disappear; but it started 42 days late, lasted only 12 days (compared to the usual 66) and cooled the waters to 23 degrees (instead of the average 19).
And yet, it is counterintuitive. First, because La Niña (the ENSO phase that ruled in 2025) It usually favors blooms in the eastern Pacific. Second, because until now we thought that warming intensifies large outcrops. And, third, because the upwelling has returned this year (with some collapses in between). None of this fits with what we have learned over 30 years of direct ‘in situ’ measurements (and satellite images).
But wait a second, what is this “outcrop” thing? It is an effect of the increase in intensity of the ‘Panama low-level jet‘; a jet that pushes surface water deeper and allows cold, nutrient-rich water from the depths of the Gulf of Panama to rise. This outcrop is key to the life of some 60,000 km2 of the Pacific.
The fact is that it is also the most predictable system in the Pacific. Since we started measuring it, he had never missed his appointment.
What happened in 2025. The allies did not have the strength to break the thermal stratification of the surface and, therefore, were not able to activate the outcrop other than as a simulation.
And why should we care? To begin with because, according to the same researcherss, “more than 95% of Panama’s marine biomass comes from the Pacific thanks to the rise of nutrients”: that is 2.76% of the GDP of the Panamanian republic. But it goes beyond the Central American country: the upwelling areas occupy less than 1% of the world’s ocean surface, but They generate around 50% of fishing catches of the planet
It also has an important oceanic and climate impact, of course; but it tells us very interesting things about what we can expect in the future.
Because if, suddenly, a phenomenon that we thought was very stable (and that we have known about for as long as we can remember) can disappear, what can happen? What, in reality, is the Gulf of Panama telling us?
Image | O’Dea et al. (2025)
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