Regional scenarios of sea level rise and impacts on Basque (Bay of Biscay) coastal habitats, throughout the 21st century

Abstract

Global climate models have predicted a rise on mean sea level of between 0.18 m and 0.59 m by the end of the 21 st Century, with high regional variability. The objectives of this study are to estimate sea level changes in the Bay of Biscay during this century, and to assess the impacts of any change on Basque coastal habitats and infrastructures. Hence, ocean temperature projections for three climate scenarios, provided by several atmosphere-ocean coupled general climate models, have been extracted for the Bay of Biscay: these are used to estimate thermosteric sea level variations. The results show that, from 2001 to 2099, sea level within the Bay of Biscay will increase by between 28.5 and 48.7 cm, as a result of regional thermal expansion and global ice-melting, under scenarios A1B and A2 of the Intergovernmental Panel on Climate Change. A high-resolution digital terrain model, extracted from LiDAR, data was used to evaluate the potential impact of the estimated sea level rise to 9 coastal and estuarine habitats: sandy beaches and muds, vegetated dunes, shingle beaches, sea cliffs and supralittoral rock, wetlands and saltmarshes, terrestrial habitats, artificial land, piers, and water surfaces. The projected sea level rise of 48.7 cm was added to the high tide level of the coast studied, to generate a flood risk map of the coastal and estuarine areas. The results indicate that 110.8 ha of the supralittoral area will be affected by the end of the 21 st Century; these are concentrated within the estuaries, with terrestrial and artificial habitats being the most affected. Sandy beaches are expected to undergo mean shoreline retreats of between 25\% and 40\%, of their width. The risk assessment of the areas and habitats that will be affected, as a consequence of the sea level rise, is potentially useful for local management to adopt adaptation measures to global climate change. (C) 2010 Elsevier Ltd. All rights reserved.