![[Translate to English:] Wenn Passatwinde im Golf von Panama das warme Küstenwasser aufs Meer hinausschieben, strömt aus 300 bis 400 Metern Tiefe kühles, nährstoffreiches Wasser nach.](/fileadmin/_processed_/b/a/csm_01-WSS-News-Seibold-upwelling_a08a676efb.png)
![[Translate to English:] Wenn Passatwinde im Golf von Panama das warme Küstenwasser aufs Meer hinausschieben, strömt aus 300 bis 400 Metern Tiefe kühles, nährstoffreiches Wasser nach.](/fileadmin/_processed_/b/a/csm_01-WSS-News-Seibold-upwelling_2e6545c2e7.png)
Seasonal upwelling fails to materialise
Every year during the dry season, cool, nutrient-rich water rises from the depths of the Gulf of Panama to the surface—every year, except this year. For the first time on record, the phenomenon has failed to materialise, as investigations conducted with the help of the research sailing yacht Eugen Seibold have shown.
Since 2023, the team aboard the Eugen Seibold—the research vessel of the Max Planck Institute for Chemistry (MPIC) in Mainz that sails with funding from the Werner Siemens Foundation—have been collecting water samples and data including temperature and wind conditions in the Tropical Eastern Pacific. Now, the team led by Gerald Haug and Ralf Schiebel has helped uncover a surprising—and very unsettling—event: for the first time in at least forty years, the upwelling system in the Gulf of Panama has failed to materialise.
The annual upwelling normally occurs during Panama’s dry season, between January and April, when strong trade winds caused by a shift in the tropical high-pressure zone arrive in the Gulf of Panama from the north-east. “These winds push warm surface water away from the coast towards the ocean—which makes room for cool, nutrient-rich water to rise from depths of three to four hundred metres,” says Ralf Schiebel, head of research on the Eugen Seibold and group leader at the Department of Climate Geochemistry at MPIC.
Originally, the Seibold team had planned to measure the upwelling phenomenon in the Gulf of Panama in March 2025. But then, two or three weeks before the measurements were scheduled to begin, Schiebel received an email from a colleague at the Smithsonian Tropical Research Institute, which has been measuring surface water temperatures for the past forty years to monitor the phenomenon. “He said their measurements were indicating that the water surface hadn’t cooled off—that the upwelling had apparently failed to materialise this year.”
No interaction between water layers
Schiebel and his team aboard the Eugen Seibold collected water samples from various depths to characterise the hydrological conditions in the Gulf of Panama, with the results confirming that the upper water layer had indeed failed to cool significantly. “And the thermocline, a transition layer where the temperature plummets at a certain depth, was intact. This means the trade winds weren’t strong enough to break up the thermocline and bring the deep water up to the surface,” Schiebel explains.
This marks the first time the upwelling event has failed to materialise since measurements began forty years ago, as the researchers wrote in a paper recently published in top-tier science journal PNAS.1 Indeed, it may be the first time for millennia. The cold-water upwelling is responsible for seasonal growth cycles of corals, and these patterns can be detected by studying their skeletons. Schiebel says investigations of fossilised corals from the Gulf of Panama indicate that the cycles have taken place consistently since the last deglaciation—which ended some eleven thousand years ago.
Fishing industry collapses
The failure of the cold-water upwelling has major consequences. On the one hand, the phenomenon helps buffer coral reefs from overheating, and on the other hand, fisheries in the Gulf of Panama depend on the event for their livelihood. When nutrient-rich waters flow up from the depths into the sunlit surface ocean, enabling algae to grow—and algae are at the start of an entire food web that is ultimately at the heart of the fishing industry, one of Panama’s most important economic sectors.
“Fishing is a seasonal business here,” Ralf Schiebel explains. “The fishers mainly go out to sea when upwelling guarantees a good catch.” This March, however, many boats stayed in the harbour. “Japanese speedboats for hunting tuna have their berths near the Eugen Seibold,” Schiebel continues. “In the past, they were frequently out at sea. But this year, they were on anchor for the whole time we were there.”
Why the seasonal upwelling failed has not yet been fully explained. What’s clear, however, is that ocean surface temperatures have risen sharply in recent years at all measurement sites. As a result, temperature differences between Equatorial Ocean and air—hence differences in atmospheric pressure—changed. “The trade winds weaken when atmospheric pressure differences decreased,” Schiebel explains.
“A complete surprise”
This effect is intensified by El Niño, the weather phenomenon that brings warm water to the Pacific coast. However, its role in the upwelling failure is difficult to quantify, as the last El Niño event dissipated in mid-2024—and was followed by its counterpart, La Niña. “Normally, the trade winds in the Gulf of Panama are stronger during La Niña than El Niño, so the absence of upwelling now came as a complete surprise,” Schiebel says.
The big question is whether the cold-water upwelling will occur again next year, or whether this is the new normal. It’s too early to speculate, says Gerald Haug, Director of the Department of Climate Geochemistry at MPIC and “father” of the Eugen Seibold. Nevertheless, he continues, the study has highlighted the growing vulnerability of tropical upwelling systems, which—despite their ecological and socio-economic importance—remain poorly monitored. Other upwelling systems similar to those in the Gulf of Panama are found along the coast West Africa, off Mauritania, Morocco and Namibia, for example.
During the next dry season, the researchers won’t be collecting samples in the Gulf of Panama. They’re currently taking measurements off the Galapagos Islands. “After we complete this work,” Schiebel says, “our next station will be the Costa Rica Thermal Dome”. Like the upwelling system in the Gulf of Panama, the dome is a major upwelling system in the Pacific, albeit one with different underlying mechanisms. And so, at the end of the year, the sailing research vessel will travel through the Panama Canal and back to the Atlantic side, where the team will continue their mission in the Atlantic Ocean.
