Bioclim Deliverable D10 - 12: development and application of a methodology for taking climate-driven environmental change into account in performance assessments

The BIOCLIM project on modelling sequential Biosphere systems under Climate change for radioactive waste disposal is part of the EURATOM fifth European framework programme. The project was launched in October 2000 for a three-year period. The project aims at providing a scientific basis and practical methodology for assessing the possible long term impacts on the safety of radioactive waste repositories in deep formations due to climate and environmental change. Five work packages have been identified to fulfill the project objectives: - Work package 1 will consolidate the needs of the European agencies of the consortium and summarize how environmental change has been treated to date in performance assessments. - Work packages 2 and 3 will develop two innovative and complementary strategies for representing time series of long term climate change using different methods to analyse extreme climate conditions (the hierarchical strategy) and a continuous climate simulation over more than the next glacial-interglacial cycle (the integrated strategy). - Work package 4 will explore and evaluate the potential effects of climate change on the nature of the biosphere systems. - Work package 5 will disseminate information on the results obtained from the three year project among the international community for further use. The output from the climate models developed and applied in WP2 and WP3 has been interpreted in WP4 ('Biosphere system description') in terms of model requirements for the post-closure radiological performance assessment of deep geological repositories for radioactive wastes, in order to develop a methodology to demonstrate how biosphere systems can be represented in the long-term. The work undertaken in WP4 is described in this report. This report describes the methodology used for identification and characterisation of specific climate states and transitions between those climate states. It also covers the application of those methods in the context of the climate modelling results produced in WP2 and WP3. Within the context of BIOCLIM, WP4 included methodology development and extended the development of illustrative conceptual models of biosphere systems and the transitions between them based on results from WP2 and WP3. This provided an appropriate basis for developing recommendations on how the effects of climate change on the biosphere can be taken into account in PAs, including the advantages/disadvantages and likely viability of potential alternative strategies. However, in order to go beyond this and evaluate which of the alternative methods of taking climate change into account should be preferred in a specific context would require application of the methodology developed under WP4 to proposed facilities at specific sites. It could also require the conceptual models of biosphere system states and transitions to be translated into mathematical models