Deliverable D4/5: Global climatic characteristics, including vegetation and seasonal cycles over Europe, for snapshots over the next 200,000 years. 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 aim of the BIOCLIM project is to develop andudpresent techniques that can be used to developudself-consistent patterns of possible futureudclimate changes over the next million years (climateudscenarios), and to demonstrate how these climateudscenarios can be used in assessments of the long-termudsafety of nuclear waste repository sites.udWithin the project, two strategies are implemented toudpredict climate change. The first is the hierarchicaludstrategy, in which a hierarchy of climate models is usedudto investigate the evolution of climate over the period ofudinterest. These models vary from very simple 2-D andudthreshold models, which simulate interactions betweenudonly a few aspects of the earth system, through generaludcirculation models (GCMs) and vegetation models,udwhich simulate in great detail the dynamics and physicsudof the atmosphere, ocean, and biosphere, to regionaludmodels, which focus in particular on the Europeanudregion and the specific areas of interest. The secondudstrategy is the integrated strategy, in whichudintermediate complexity climate models are developed,udand used to consecutively simulate the development ofudthe earth system over many millennia. Although theseudmodels are relatively simple compared to a GCM, theyudare more advanced than 2D models, and do includeudphysical descriptions of the biosphere, cryosphere,udatmosphere and ocean.udThis deliverable, D4/5, focuses on the hierarchicaludstrategy, and in particular the GCM and vegetationudmodel simulation of possible future climates.udDeliverable D3 documented the first step in thisudstrategy. The Louvain-la-Neuve 2-D climate modelud(LLN-2D) was used to estimate (among other variables)udannual mean temperatures and ice volume in theudNorthern Hemisphere over the next 1 million years.udIt was driven by the calculated evolution of orbitaludparameters, and plausible scenarios of CO2udconcentration. From the results, 3 future time periodsudwithin the next 200,000 years were identified as beingudextreme, that is either significantly warmer or coolerudthan the present. The next stage in the hierarchicaludstrategy was to use a GCM and biosphere model, toudsimulate in more detail these extreme time periods.