Climate change in the Canary/Iberia upwelling region: the role of ocean stratification and wind

Abstract

The Canary/Iberia region (CIR), part of the Canary Current Upwelling System, is well-known for its coastal productivity and crucial role in enriching the oligotrophic open ocean through the offshore transport of the upwelled coastal waters. Given its significant ecological and socio-economic importance, it is essential to assess the impact of climate change on this area. Therefore, the goal of this study is to analyze the climate change signal over the CIR using a high-resolution regional climate system model driven by the Earth system model MPI-ESM-LR under RCP8.5 scenario. This modelling system presents a regional atmosphere model coupled to a global ocean model with enough horizontal resolution at CIR to examine the role of the upwelling favourable winds and the ocean stratification as key factors in the future changes. CIR exhibits significant latitudinal and seasonal variability in response to climate change under RCP8.5 scenario, where ocean stratification and wind patterns will play both complementary and competitive roles. Ocean stratification will increase from the Strait of Gibraltar to Cape Juby by the end of the century, weakening the coastal upwelling all year long. This increase in stratification is associated with a freshening of the surface layers of the North Atlantic. However, modifications in the wind pattern will play a primary role in upwelling source water depth changes in the southernmost region of the CIR in winter and in the north of the Iberian Peninsula in summer. Wind pattern changes are related to the intensification of the Azores High in winter and to a deepening of the Iberian thermal low in summer months.