Regional marine climate scenarios in the NE Atlantic sector close to the Spanish shores

Abstract

We present an overview of the changes expected during the 21st century in key marine parameters (sea surface temperature, sea surface salinity, sea level and waves) in the sector of the NE Atlantic Ocean close to the Spanish shores. Under the A1B scenario, open-sea surface temperatures would increase by 1°C to 1.5°C by 2050 as a consequence of global ocean warming. Near the continental margin, however, the global temperature rise would be counteracted by an enhancement of the seasonal upwelling. Sea surface salinity is likely to decrease in the future, mainly due to the advection of high-latitude fresher waters from ice melting. Mean sea level rise has been quantified as 15-20 cm by 2050, but two contributions not accounted for by our models must be added: The mass redistribution derived from changes in the large-scale circulation (which in the NE Atlantic may be as large as 15 cm in 2050 or 35 cm by 2100) and the increase in the ocean mass content due to the melting of continental ice (for which estimates are still uncertain). The meteorological tide shows very small changes, and therefore extreme sea levels would be higher in the 21st century, but mostly due to the increase in mean sea level, not to an increase in the storminess. The wave projections point towards slightly smaller significant wave heights, but the changes projected are of the same order as the natural variability.