Climate Change Impacts on the Humboldt Upwelling System: Insights from CROCO Bio-EBUS Model Upwelling Indices.
Supervisors: Xue Tianfei, Ivy Frenger (GEOMAR)
Coastal upwelling is fundamental to Eastern Boundary Upwelling Systems (EBUS), supporting high productivity and marine diversity. The Northern Humboldt Current System (NHCS), among the most productive EBUSs, is particularly noted for its high fish catches due to persistent upwelling. This study investigates the interannual variability and climate change impacts on upwelling in the NHCS. We evaluated several upwelling indices based on wind, nitrogen, and sea surface temperature to identify the one that best correlates with upward velocity and biogeochemistry in the high-resolution CROCO-BioEBUS model. To assess climate change effects, we performed sensitivity experiments with increased temperature and varying wind speeds—both increases and decreases. This approach allowed us to simulate distinct climate change scenarios. Our results show that the wind-based AV upwelling index is most effective for upward velocity, while the wind-based CUTI and nitrogen-based BEUTI indices better correlate with biogeochemical factors like nitrogen and chlorophyll. The climate change scenarios ([T+] and [W-]) revealed a one-month shift in the timing of the upwelling maximum intensity, potentially impacting marine species. Overall, our findings suggest that by the end of the century, climate change could have a greater impact on upwelling and nutrient dynamics than extreme El Niño events.