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)

Abstract

The overall aim of BIOCLIM is to assess the
possible long-term impacts due to climate
change on the safety of radioactive waste
repositories in deep formations. This aim is addressed
through the following specific objectives:
• Development of practical and innovative strategies for
representing sequential climatic changes to the
geosphere-biosphere system for existing sites over
central Europe, addressing the timescale of one
million years, which is relevant to the geological
disposal of radioactive waste.
• Exploration and evaluation of the potential effects of
climate change on the nature of the biosphere
systems used to assess the environmental impact.
• Dissemination of information on the new
methodologies and the results obtained from the
project among the international waste management
community for use in performance assessments of
potential or planned radioactive waste repositories.
The BIOCLIM project is designed to advance the
state-of-the-art of biosphere modelling for use in
Performance Assessments. Therefore, two strategies
are developed for representing sequential climatic
changes to geosphere-biosphere systems. The
hierarchical strategy successively uses a hierarchy of
climate models. These models vary from simple 2-D
models, which simulate interactions between a few
aspects of the Earth system at a rough surface
resolution, through General Circulation Model (GCM)
and vegetation model, which simulate in great detail the
dynamics and physics of the atmosphere, ocean and
biosphere, to regional models, which focus on the
European regions and sites of interest. Moreover,
rule-based and statistical downscaling procedures are
also considered. Comparisons are provided in terms of
climate and vegetation cover at the selected times and
for the study regions. The integrated strategy consists
of using integrated climate models, representing all
the physical mechanisms important for long-term
continuous climate variations, to simulate the climate
evolution over many millennia. These results are then
interpreted in terms of regional climatic changes using
rule-based and statistical downscaling approaches.
This deliverable, D6a, focuses on the hierarchical
strategy, and in particular the MAR simulations.
According to the hierarchical strategy developed in
the BIOCLIM project to predict future climate, six
BIOCLIM experiments were run with the MAR model. In
addition to these experiments a baseline experiment,
presenting the present-day climate simulated by MAR,
was also undertaken. In the first step of the hierarchical
strategy the LLN 2-D NH climate model simulated
the gross features of the climate of the next 1 Myr
[Ref.1]. Six snapshot experiments were selected from
these results. In a second step a GCM and a biosphere
model were used to simulate in more detail the climate
of the selected time periods. These simulations were
performed on a global scale [Ref.1]. The third step of
the procedure is to derive the regional features of the
climate at the same time periods. Therefore the results
of the GCM are used as boundary conditions to force
the regional climate model (MAR) for the six selected
periods and the baseline simulation. The control
simulation (baseline) corresponds to the regional
climate simulated under present-day conditions, both
insolation forcing and atmospheric CO2 concentration.
All the BIOCLIM simulations are compared to that
baseline simulation. In addition, other comparisons will
also be presented. Tableau 1 summarises the
characteristics of these BIOCLIM experiments already
presented in [Ref.1] and [Ref.2].