Der Ozean hörte auf, Panamas Ufer abzuatmen. Zwischen Dezember und April dieses Jahres blieb die Meeresoberflächentemperaturen wärmer, die biologische Produktivität nachgelassen, und ein vorhersehbares saisonales Muster, auf das sich die Küstengemeinden seit Jahrtausenden verlassen haben, verschwand einfach.

During the dry season in Central America (generally between December and April), northern trade winds generate upwelling events in the ocean waters of the Gulf of Panama. Upwelling is a process that allows cold, nutrient-rich waters from the depths of the ocean to rise to the surface. This dynamic supports highly productive fisheries and helps protect coral reefs from thermal stress. Thanks to this movement of water, the sea along Panama’s Pacific beaches remains cooler during the „summer“ vacation season.

Scientists from the Smithsonian Tropical Research Institute (STRI) have studied this phenomenon and their records show that this seasonal upwelling, which occurs from January to April, has been a consistent and predictable feature of the gulf for at least 40 years. However, researchers recently recorded that in 2025, this vital oceanographic process did not occur for the first time. As a result, the typical drops in temperature and spikes in productivity during this time of year were diminished. In the recently published article in the journal PNAS, scientists suggest that a significant reduction in wind patterns was the cause of this unprecedented event, revealing how climate disruption can quickly alter fundamental oceanic processes that have sustained coastal fishing communities for thousands of years. Still, further research is needed to determine a more precise cause and its potential consequences for fisheries.

This finding highlights the growing vulnerability of tropical upwelling systems, which, despite their enormous ecological and socioeconomic importance, remain poorly monitored. It also underscores the urgency of strengthening ocean-climate observation and prediction capabilities in the planet’s tropical regions.

This result marks one of the first major outcomes of the collaboration between the S/Y Eugen Seibold research vessel from the Max Planck Institute and STRI.

[https://www.pnas.org/doi/10.1073/pnas.2512056122](https://www.pnas.org/doi/10.1073/pnas.2512056122)

To briefly contextualise this, because it is actually quite interesting:
Right next to the Gulf of Panama, separated by the Azuero Peninsula, lies the smaller Gulf of Chiriquí, which has a completely different hydrological regime, meaning that the wind-driven upwelling process of cooler water layers mentioned in the article does not occur there in the same way (because there are no similar topographical depressions in the Cordillera where fast, strong winds blow across the isthmus), resulting in a heterogeneous landscape relatively close together.

This naturally lends itself to drawing a few comparisons and elaborating a little on corals: Many reef-building stony corals like stable, warm and nutrient-poor conditions (to put it simply, the biodiversity and corresponding niches are of course almost impossible to grasp, but Pocillopora sp. dominates in this region and are essentially the ‘chief builders’) and severely restrict their growth during upwelling phases.
As a result, there are relatively many coral reefs in the Gulf of Chiriquí, they recover more quickly after ENSO events and have also grown better in recent years. The Randall et al. paper from 2020 cited by the authors confirms this once again, with one big and important caveat: this may and likely will change in the future. This is also referred to in the short sentence in the press release, because the upwelling makes it easier to buffer heat waves, provided they come at the right time. However, predicting this synchronicity is very difficult and, as always, is influenced by many factors (especially thanks to ENSO).
Nevertheless, the trend of both regions warming rapidly and oscillating more strongly in terms of temperature is well documented, even if, according to the model by Kim et al. that I am familiar with, the ENSO amplitude will decrease again from 2040 onwards.

The phytoplankton explosion (mainly evaluated using satellite data on chlorophyll a areas; in this study, surface water temperatures, in-situ logs and water column sampling by the Eugen Seibold) benefits completely different animal species, especially pelagic fish species, which has a significant impact on the composition of the food chain. This, in turn, is more important for ‘us’ (i.e. the local fishermen and coastal communities) because important commercial target species are more strongly represented. However, this does not necessarily say anything about the quality and condition of the respective ecosystems.

For the sake of completeness, it should also be mentioned that there are also non-wind-driven upwelling processes in the Gulf of Chiriquí, where the thermocline rises locally due to tides, internal waves and convection or precipitation processes.

Out of all the times to be born, I get to watch the end of the world.