Deliverable D6a: Regional climatic characteristics for the European sites at specific times: the dynamical downscaling. Work Package 2, Simulation of the future evolution of the biosphere system using the hierarchical strategy. Modelling Sequential Biosphere Systems under Climate Change for Radioactive Waste Disposal (BIOCLIM)

摘要

The overall aim of BIOCLIM is to assess theudpossible long-term impacts due to climateudchange on the safety of radioactive wasteudrepositories in deep formations. This aim is addressedudthrough the following specific objectives:ud• Development of practical and innovative strategies forudrepresenting sequential climatic changes to theudgeosphere-biosphere system for existing sites overudcentral Europe, addressing the timescale of oneudmillion years, which is relevant to the geologicaluddisposal of radioactive waste.ud• Exploration and evaluation of the potential effects ofudclimate change on the nature of the biosphereudsystems used to assess the environmental impact.ud• Dissemination of information on the newudmethodologies and the results obtained from theudproject among the international waste managementudcommunity for use in performance assessments ofudpotential or planned radioactive waste repositories.udThe BIOCLIM project is designed to advance theudstate-of-the-art of biosphere modelling for use inudPerformance Assessments. Therefore, two strategiesudare developed for representing sequential climaticudchanges to geosphere-biosphere systems. Theudhierarchical strategy successively uses a hierarchy ofudclimate models. These models vary from simple 2-Dudmodels, which simulate interactions between a fewudaspects of the Earth system at a rough surfaceudresolution, through General Circulation Model (GCM)udand vegetation model, which simulate in great detail theuddynamics and physics of the atmosphere, ocean andudbiosphere, to regional models, which focus on theudEuropean regions and sites of interest. Moreover,udrule-based and statistical downscaling procedures areudalso considered. Comparisons are provided in terms ofudclimate and vegetation cover at the selected times andudfor the study regions. The integrated strategy consistsudof using integrated climate models, representing alludthe physical mechanisms important for long-termudcontinuous climate variations, to simulate the climateudevolution over many millennia. These results are thenudinterpreted in terms of regional climatic changes usingudrule-based and statistical downscaling approaches.udThis deliverable, D6a, focuses on the hierarchicaludstrategy, and in particular the MAR simulations.udAccording to the hierarchical strategy developed inudthe BIOCLIM project to predict future climate, sixudBIOCLIM experiments were run with the MAR model. Inudaddition to these experiments a baseline experiment,udpresenting the present-day climate simulated by MAR,udwas also undertaken. In the first step of the hierarchicaludstrategy the LLN 2-D NH climate model simulatedudthe gross features of the climate of the next 1 Myrud[Ref.1]. Six snapshot experiments were selected fromudthese results. In a second step a GCM and a biosphereudmodel were used to simulate in more detail the climateudof the selected time periods. These simulations wereudperformed on a global scale [Ref.1]. The third step ofudthe procedure is to derive the regional features of theudclimate at the same time periods. Therefore the resultsudof the GCM are used as boundary conditions to forceudthe regional climate model (MAR) for the six selectedudperiods and the baseline simulation. The controludsimulation (baseline) corresponds to the regionaludclimate simulated under present-day conditions, bothudinsolation forcing and atmospheric CO2 concentration.udAll the BIOCLIM simulations are compared to thatudbaseline simulation. In addition, other comparisons willudalso be presented. Tableau 1 summarises theudcharacteristics of these BIOCLIM experiments alreadyudpresented in [Ref.1] and [Ref.2].