Impacts of Andean uplift on the Humboldt Current system: A climate model sensitivity study

Using both an atmospheric global circulation model and a regional oceanic model, we assess the impact of the Andes uplift on the Humboldt Current system (HCS). With three topographic scenarios for the Andes, we show that the uplift played a crucial role in shaping the lower troposphere dynamics over the Pacific Ocean and in turn affected the physical characteristics of the system. Our results show that the uplift has triggered a marked southward shift of the HCS, changing the latitudinal position of coastal upwelling areas as well as the strength of the South Pacific gyre. Our oceanic modeling experiments show that the latitudinal pattern of sea surface temperatures is dramatically modified with reduced Andes, with anomalies reaching up to 3 degrees C. We discuss the feedbacks of these changes on South American climate as well as the potential onset of an altitudinal threshold that would have had triggered these changes.