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Irantzu Zubiaur

AZTI-Tecnalia

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izubiaur@azti.es

(+34) 946574000

2010/7/19

The sea level of the Gulf of Biscay could rise to 49 cm by the end of the present century, according to research by AZTI-Tecnalia

The coast along the Basque province of Gipuzkoa could be affected in over 111 hectares by a rise in sea level of up to 49 cm, forecast for the end of the present century, according to results of research undertaken by AZTI-Tecnalia in collaboration with the Mediterranean Institute of Advanced Studies (CSIC-UIB).

Moreover, the average level of the sea along the Cantabrian coastline has risen 2.1 millimetres per year between 1943 and 2004 – 12.8 cm in 61 years. Scientists at the Basque technological centre have carried out studies on the evidence and impact of climate change on the Basque coastline and estuaries, which have been published in the international journal Estuarine, Coastal and Shelf Science, and which has formed the basis of a video.

The mareographic measurements from Santander reveal that the sea level along the Cantabrian coastline rose 2.1 millimetres per year between 1943 and 2004. This rise agrees with the analysis of the series of mareographs along the Bilbao and St. Juan de Luz stretch of littoral, the register of which are shorter.

Projections have also been made of the temperature of the ocean at three scenarios of greenhouse effect gas emissions in the Gulf of Biscay, obtained using a number of general atmospheric-oceanic climate models; these projections are used to estimate the variations of the sea level due to changes in temperature. The results show that, with scenarios considered by the Intergovernmental Group of Experts on Climate Change, between 2001 and 2099 the level of the sea of the Gulf of Biscay will rise by between 28.5 and 48.7 cm as a result of thermal expansion and the global melting of ice.

In order to evaluate the potential impact of the estimated rise in the sea level on coastal and estuarial habitats, LIDAR technology was used, enabling a determination of the distance from a laser emitter to an object or surface using a pulsed laser beam. In this way, a high-resolution digital model of the terrain is generated. To the high tide level of the coastline under study the projected rise of the sea (48.7 cm) was added in order to generate a flood risk map of the Gipuzkoan coast. The results indicate that 111 hectares of the coastal zone would be affected by the end of the XXI century; these being concentrated around the estuaries, the most affected terrestrial and artificial habitats. It is expected that the sand beaches will undergo a retreat along the coastline by an average of between 25% and 40% of their current width.

While the impact of the current rise in sea level along the coast is relevant, they are less evident due to the strong pressure exerted by human activities. Thus the Gipuzkoan coast has lost three hectares of beaches and salt marshes between 1954 and 2004 due to the rise in sea level, while139 hectares of coastal habitat have been transformed, 98 of which have altered due to direct activity by humans.

The risk evaluation of the areas and habitats that would be affected by the seawater level rise is potentially useful for government bodies in taking measures for adapting to global climate change.

The research is within the remit of the K-Egokitzen project, the aim of which is to analyse the impact of climate change in Euskadi and evaluate the necessary adaptation changes. The K-Egokitzen project is being led by Labein-Tecnalia and co-financed by the Basque Government Departments of the Environment, Territorial Planning and Agriculture and Fisheries and of Industry and Innovation, through the ETORTEK programme.

An educational and information video

AZTI-Tecnalia has made a video based on the most important conclusions of the research and entitled ‘Climate change in the Basque Country, rise in sea level’ (Spanish and Basque versions). Of an educational and informative nature, the audiovisual presentation will be placed at the disposal of the university faculties linked with the sea and the environment, school centres, local authorities along the coast, maritime interpretation centres and other bodies interested in the matter.