CECILE - Coastal Environment Changes: Impact of sea Level rise (ANR CEP 2009)

CECILE - Coastal Environment Changes: Impact of sea Level rise (ANR CEP 2009) is co-funded by the Agence Nationale de la Recherche and certified by Aerospace Valley.

 

The CECILE project brings together 8 partners (BRGM, LEGOS, Météo France, CNRS, LIENSS, Cerfacs, CREOCEAN, SHOM). Its mission is to analyse the vulnerability of coastal areas faced with the phenomenon of rising sea levels by examining positions at several levels in the scale as part of an integrated approach that takes account of the multi-factor aspect of the process.

The project is jointly run by the BRGM (project coordination) and LEGOS (scientific coordination), with a 45-month mission (January 2010 to September 2013).

 

Work packages

 

The project comprises six work packages:

• WP1: Selection of study areas and gathering of any kind of information that might allow characterization of coastline shifts in these regions.
• WP2 and WP4 take a look at the climatic causes of past and future variations in ocean levels.
• WP3: Multi-scale analysis of the relative rise in sea levels. This concentrates on the systematic analysis of collected bathymetric data in order to bring out trends, isolate indications, or correct old biases.
• WP5: Development of an integrated methodology based on precise indicators for identifying the causes of coastline shift and assessing future impacts with respect to terrain type and time scale.
• WP6: Distribution and development of the research results.

 

Study areas

 

Past and future sea level changes are studied on a global scale and across smaller areas likely to provide valuable studies on sea level rise and its potential impacts.

The areas selected include the French overseas territories and departments (New Caledonia, French Polynesia, Reunion) where the project partners are reconstructing past changes in sea level and have research and data on geomorphology and recent coastal dynamics. The Gulf of Mexico and the Mediterranean basin are also being investigated to study sea level changes. Finally, the north-eastern Atlantic is a good site for assessing the 10-year forecasts of variations in sea level.

 

Reconstruction of sea level changes over the past 50 years

The Pacific Islands are generally considered to be among the regions most vulnerable to climate change and to rising sea levels now and in the future. The study by Becker et al. (2011), conducted under the CECILE project, has reconstructed sea level rise and variability since 1950 in the western tropical Pacific

 

Overall sea level variation has been assessed for some islands, taking climate variability and climate change into account as well as vertical land movements when the data is available. A global sea level field was reconstructed from 1950 to 2009, combining long (over 1950–2009) good quality tide gauge records with 50-year-long (1958–2007) gridded sea surface heights from the Ocean General Circulation Model DRAKKAR

The results show that some islands of the region have seen significant sea level rise during the past 60 years. This is especially the case for Funafuti Island (Tuvalu) where the rate of rise was about 3 times greater than the global mean sea level rise over 1950–2009, taking into account climate-related sea level components and subsidence affecting the atoll.

 

 

Processes involved in multi-decadal changes in shorelines around atolls. Source: after Garcin et al. 2011.

 

 

 

The results show that some islands of the region suffered significant sea level rise during the past 60 years. This is especially the case for Funafuti Island (Tuvalu) where the rate of rise is found to be about 3 times larger than the global mean sea level rise over 1950–2009, if one takes into account climate-related sea level components and subsidence affecting the atoll.

 

 

Other results

The current focus of CECILE project work is to assess whether these rapid changes in sea level have accentuated coastline erosion. Initial results (presented by Garcin et al., 2011) suggest that the variability of shoreline change is primarily linked to wave and storm action in French Polynesian atolls with little human presence.

A reconstruction of sea level rise at global scale has been produced (Meyssignac et al., 2011a), as well as an analysis of the causes of spatial variability in sea level variations (Meyssignac et al., 2011b). Santamaria-Gomez et al. (2010) have published research on the accuracy of permanent GPS data, which are used to measure ground movements that may affect tide gauges.

Finally, studies have been published (Rogel and Salas y Mélia, 2011) on future decadal and centennial sea level rise, and are continuing in the second part of the project as post-doc research.

Becker et al. (2011) have produced a more specific analysis of sea level variations in the Pacific, which is used in Garcin et al.(2011) and in ongoing studies to assess whether and how far these sea level variations have resulted in more pronounced erosion in the French Polynesian and New Caledonian sites. A summary of these results is given in Le Cozannet et al. 2011.

 

To find out more:

• ANR CECILE website
• The first newsletter published in January 2012 presents the significant results of the first 18 months of the Cecile project..

 

References

• Becker M., Meyssignac B., Llovel W., Cazenave A. and Delcroix T. Sea level variations at Tropical Pacific Islands during 1950-2009. Global and Planetary Change, 80/81, 85-98, 2012 (see related REFMAR news).
• Wöppelmann, G. and M. Marcos, Coastal sea level rise in southern Europe and the non-climate contribution of vertical land motion, J. Geophys. Res., Vol. 117, C01007, doi:10.1029/2011JC007469, 2012
• Meyssignac B., Becker M., Llovel W. and Cazenave A. An assessment of two-dimensional past sea level reconstructions over 1950 -2009 based on tide gauge data and different input sea level grids, Surveys in Geophysics, in press,. doi: 10.1007/s10712-011-9171-x
• Meyssignac B., Salas y Melia D., Llovel W., Becker M and Cazenave A.,Spatial trend patterns in observed sea level: internal variability and/or anthropogenic signature ? submitted, Climate of the Past, 2011.
• Le Cozannet G., Cazenave A., Garcin M., Becker M., Donato V., Rogel P., Salas y Mélia D., Walker P., Wöppelmann G., Yates-Michelin M., 2011: l'élévation récente du niveau marin et l'érosion côtière: le cas d'îles récentes du Pacifique. Géosciences n°14—Décembre 2011.

 

 

Last updated 12/12/2012