Assessing future climate change in the Iberian Upwelling System

Cordeiro Pires, A., Nolasco, R., Rocha, A. and Dubert, J., 2013. Assessing future climate change in the Iberian Upwelling System

The Western Iberian Margin is the northern limit of the Canary Upwelling System, a region of strong mesoscale activity, seasonal variability and thus very likely to be sensitive to climate change. Using a regional ocean model and data from several coupled global climate models (CGCM), climatological simulations were set up for present and for a future scenario. Forcing is obtained from averaging the outputs of an ensemble of CGCM provided by the Intergovernmental Panel for Climate Change (IPCC) A2 emission scenario. Results are focused on the continental shelf (~200 m). In general, the sea surface temperature (SST) seasonal evolution shows, for the future, an increase of about 1°C during the upwelling season (April to September) and 2°C in the rest of the year, while sea surface salinity (SSS) shows a freshening of about −0.2. These results agree with a general increase in air temperature and in fresh water input resulting from ice melting in the North Pole, which characterize this future scenario. However, differences depend on latitude and distance from the coast (higher differences to the south and more offshore, respectively). Also, SSS undergoes a shift of its minimum from July to May or September. Cross-shore sections show that SST and SSS differences are mainly observed in the upper 200 m. In winter, the typical upper slope poleward flow undergoes a slight weakening and shallowing. In summer, while the upwelling jet intensifies at the surface, it is also more restricted in both width and depth.