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Responses to coastal climate change: Innovative Strategies for high End Scenarios - Adaptation and Mitigation

While there has been a strong focus on mitigating climate change to below 2°C, the lack of international action and the continued growth in greenhouse gas concentrations make it important to analyse the implications of higher-end scenarios (global average warming > 2°C with respect to pre-industrial level) for vulnerable areas. This will allow a better quantification of impacts and vulnerabilities associated with such climate change, showing that adaptation is possible at an affordable cost (compared to risk). It will furthermore inform policy and decision makers, contributing to raise awareness on the multiple dimensions of possible adaptation pathways.

Coastal zones are amongst the most vulnerable regions of the world in the face of climatic change (threatened by sea-level rise, run-off into coastal lowlands and coastal storms). The obtained results are based on a set of models that consider global projections especially prepared for coastal systems to allow evaluating climate change impacts for present adaptation levels.

The RISES-AM- working hypothesis is that coastal zone sustainability can be enhanced by adopting a flexible adaptive pathway that identifies tipping points and makes use of green intervention options, more sustainable than the traditional coastal engineering solutions. To achieve this general goal the project aimed to:

a) develop a set of adaptation pathways for selected vulnerable coastal systems, introducing retreat and accommodation strategies and including local scale derived innovative solutions;

b) assess synergies between these options under a range of future scenarios, considering the physical and the socio-economic components, and;

c) introduce a risk approach into climatic analysis to achieve a higher level of objectivity in the assessments and to account for uncertainties in drivers and responses. This will lead to a better assessment of the compatibility between local, regional and global scales and between short term and long term plans.

RISES –AM- was based on a nested assessment approach across scales to determine vulnerability and risk. Firstly, world regions were compared and the main vulnerability hot spots were determined as a function of coastal typology. This was be followed by regional refined analyses and local assessments, including the performance of novel types of “green” interventions.

The most efficient interventions informed regional scale analysis where adaptation paths were developed and classified, according to their contribution to climate mitigation. This was then used to reassess an improved global scale analysis.

This approach aimed at an enhanced natural functioning of “green” coastal interventions that will result in a more sustainable coastal system functioning under extreme climatic and socio-economic scenarios.

The results of RISES-AM- have been derived from conceptual and numerical models that deal with impact projection for coastal systems and allow evaluating climate impacts for present adaptation levels.  The adaptation deficit was considered as a function of coastal archetype. The local scale analysis has addressed processes not often considered together such as flooding erosion and salinization (e.g. salinity levels in one of our case studies the Ebro Delta in the Spanish Mediterranean coast). The regional vulnerabilities were assessed by characterizing coastal typologies along selected coastal stretches where future mean sea level, surges and wave conditions were projected and combined with space availability so as to determine adaptation levels and possible interventions and pathways. At the global scale a similar assessment was carried out considering in a combined manner flooding and erosion and introducing for the first time retreat as an adaptation option. The results of thee assessments show the importance of planning ahead in all categories to reduce climate change impacts and show the feedbacks between the physical and socio-economic sub-systems in the coastal zone. For this purpose interventions were taken into account which are a combination of a) grey interventions based on rigid structures, b) green interventions based on natural principles and c) soft interventions based on sand nourishment and land planning. The direct economic effects have been estimated based on land availability while a number of analysis have been carried out to calculate indirect effects (e.g. via sea transport responsible for more than 80% world trade).

The benefits of adaptation and the need for flexibility to enhance coastal sustainability have been addressed using a process based analysis. It was shown how sustainability can be enhanced by providing additional sedimentary volumes supported by enhanced water fluxes. The role of natural habitats and ecosystem functioning has also been considered to promote energy friendly types of interventions so that natural accretion mechanisms, well known for wetlands, can be exported to other coastal systems.

The general suitability of non-conventional interventions such as rising land levels (e.g. Netherlands or Maldives) versus vegetation based approaches was analysed as well. This allowed raising new questions that were not so clearly identified before. For instance the concept of high-end conditions and whether that refers to pressures acting on a coastal system or to the combination of pressures, state and responses. Another question identified is the need to combine average trends and extreme events so as to find the worst possible combination and assess from that coastal vulnerability.

Universitat Politecnica de Catalunya ES
Institutul National De Cercetare-Dezvoltare Pentru Geologie RO
Institut De Recerca I Tecnologia Agroalimentaries ES
University of Southampton UK
Stichting Deltares NL
Christian-Albrechts-Universitaet Zu Kiel DE
Natural Environment Research Council UK
Helmholtz-Zentrum Geesthacht Zentrum Fur Material-Und Kustenforschung Gmbh DE
Stichting Vu-Vumc NL
Gcf - Global Climate Forum Ev DE
Centro Euro-Mediterraneo Sui Cambiamenti Climatici Scarl IT
University of Sussex UK