Unprecedented suppression of Panama’s Pacific upwelling in 2025

Abstract

The Gulf of Panama’s (GOP) seasonal upwelling system has consistently delivered cool, nutrient-rich waters via northerly trade winds every January–April for at least 40 y. Here, we document the failure of this normally highly predictable phenomenon in 2025. Data suggest that the cause was a reduction in Panama wind-jet frequency, duration, and strength, possibly related to the Intertropical Convergence Zone (ITCZ) position during the 2024–2025 La Niña, though the mechanisms remain unclear. Nevertheless, the consequences are likely significant, including decreases in fisheries productivity and exacerbated thermal stress on corals that typically benefit from upwelling’s cooling. This event underscores how climate disruption can threaten wind-driven tropical upwelling systems, which remain poorly monitored and studied despite their importance to ecology and coastal economies.

Coastal upwelling systems support disproportionately high marine productivity and biodiversity relative to their spatial extent (1), particularly in oligotrophic tropical seas where seasonal upwelling fundamentally shapes marine ecology and fisheries (2). In the Gulf of Panama (GOP), this process occurs with remarkable predictability when the Intertropical Convergence Zone reaches its southernmost position (January–April), generating northerly trade winds that funnel through the topographic low of the Canal Zone to form the Panama low-level jet and drive strong nearshore upwelling across ~60,000 km² of Pacific Ocean (3–5). This upwelling delivers critical ecological and economic benefits: nutrient-rich deep waters fuel phytoplankton (6) that support productive food webs (7) and fisheries (8), while cool upwelled waters provide thermal buffers that moderate coral bleaching events (9). Here, we document the unprecedented suppression of upwelling in the GOP during 2025.

Methodology

We analyzed GOP temperatures using 40 y of satellite sea surface temperature (SST) records (1985–2025), 30 y of in situ logs (1995–2025), and water column profiles from the S/Y Eugen Seibold (10) to calculate upwelling onset, duration, and intensity metrics. Wind speed and stress data were analyzed and compared with ERA5 modelled regional anomalies. Complete methodology is available in SI Appendix, Extended Methods and all study data and code are available at ref. 11.

Results

Data revealed unprecedented suppression of GOP upwelling in 2025 (Figs. 1 and 2A). Historically, upwelling began by January 20th, persisted for 66 d, and reached minimum temperatures of 19 °C (extremes 14.9 °C) (Fig. 2 B, D, and E). The 2025 season deviated markedly: Temperatures dropped below 25 °C on March 4th (42 d late; Fig. 2B), persisted only 12 d (82% reduction; Fig. 2D), reached minimum temperatures of just 23.3 °C (Fig. 2E), and accumulated progressively fewer cold days than any historical year (Fig. 2C). Water column profiles showed typical upwelling structure in March 2024 versus strong stratification in 2025 (Fig. 2F). Upwelling began significantly earlier during El Niño versus La Niña, but duration and minimum temperature did not differ significantly between El Niño–Southern Oscillation (ENSO) states (SI Appendix).

Fig. 1.

Wind-jet upwelling in the GOP. (A) Typical wind vectors and SST through the topographic low in the Isthmus of Panama showing reduced sea surface temperatures in the Gulf (Feb 4, 2019). Symbols indicate temperature sensors (circles), temperature profiles (star), wind station (triangle), and satellite data region (square). (B) Daily satellite-derived SST 1985–2025. Dashed line shows the lowest 2025 SST (27.5 °C); gray arrow indicates anomalous 2025.

Fig. 2.

Conditions in the GOP comparing 2025 (red) with historical values (blue). (A) Daily SSTs showing 1995–2024 average with ±2 SD (gray ribbon). Dashed line indicates upwelling threshold. (B) The first day SST dropped below 25 °C. (C) Cumulative upwelling days with the 1995–2024 average (blue) and 2025 (red). (D) Number of days Jan–May when SST < 25 °C. (E) Minimum mean daily SST Jan–May. (F) Temperature–depth profiles from conductivity, temperature, and depth casts. (G) Northerly wind speeds. (H) Meridional wind stress τ^γ during northerly winds (negative values indicate upwelling-favorable stress). (I) Frequency of northerly winds. (J) Total wind relaxation hours. (K) Cumulative upwelling-favorable wind stress. (L) ERA5 regional wind speed anomalies during first quarter 2025.

Wind analysis revealed that when northerly winds occurred, speeds (Fig. 2G) and meridional stress (Fig. 2H) matched historical levels, but frequency was 74% lower (Fig. 2I), relaxation hours increased 25% (Fig. 2J), and cumulative wind forcing was substantially reduced (Fig. 2K). Regional analysis confirmed anomalously low offshore wind speeds in 2025 (Fig. 2L).

Discussion

The unprecedented failure of upwelling in the GOP in 2025 (Fig. 2 A–F) appears linked to anomalous wind patterns, particularly reduced frequency, strength, and duration of wind-jet formation (Fig. 2 G–L). When northerly winds formed, they were as strong in 2025 as in any previous year (Fig. 2 G and H), but occurred significantly less frequently, for shorter periods and accumulated less wind stress (Fig. 2 I–K). These nearshore observations are also reflected in the anomalous reduction in offshore wind speeds in the GOP region (Fig. 2L), providing a plausible mechanism for the 2025 upwelling failure.

La Niña conditions have been proposed to diminish wind jet formation through more northerly ITCZ positioning (5), but the 2025 upwelling failure occurred during a weak La Niña with the Gulf experiencing far stronger ENSO cycles without upwelling failure. While winds are intensifying in temperate eastern boundary upwelling systems (12), responses are highly spatially variable (13). Panama’s 2025 upwelling failure underscores that regional-scale dynamics, rather than blanket global predictions, are essential for understanding these tropical upwelling systems.

Pacific upwelling on the Isthmus has been a predictable and fundamentally important seasonal event across multiple timescales, with marine communities (7), pre-Columbian societies (14), and modern fisheries (ref. 8 [CeDePesca]) becoming reliant upon this reliable phenomenon. Failed upwelling will likely reduce primary productivity with cascading effects through marine food webs and declines in commercial and subsistence fisheries (8, 15). Of equal concern is the potential exacerbation of thermal stress on coral reefs, which without upwelling likely face more prolonged thermal stress, potentially leading to more extensive bleaching (16).

Whether the 2025 event signals the first of future failed upwellings warrants investigation through enhanced monitoring, predictive modelling, and targeted research on the interactions between oceanography, ecology, and human resource dependence in tropical upwelling systems.

Supplementary Material

Appendix 01 (PDF)

Data, Materials, and Software Availability

All study data and code are available at Zenodo (11).