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Abstract
Increasing demand for policy impact assessment regarding social,
economic and environmental aspects asks for combined application
of different models and tools. The paper discusses concepts and
challenges in linking models, taking CAPRI (Common Agricultural
Policy Regionalised Impact) model as an example. CAPRI combines
different economic models, spatial downscaling and interfaces to
bio-physical components. 250 non-linear regional programming
models with econometrically estimated costs functions cover the
EU-27, Norway and Western Balkans. They are consistently linked to
a spatial globally closed trade model, covering 60 countries / country
blocks and 50 primary and secondary agricultural products. The
link is based on sequential calibration: the market models prices
drive the programming models whereas its supply and feed demand
curves are calibrated to the programming models’ results, iteratively
repeated to convergence. CAPRI integrates projection results from
other model systems in the baseline generation and calibrates the
supply models to econometric estimations or the supply response
from other models as in SEAMLESS. The spatial down-scaling
component breaks down the regional EU-27 results regarding cropping
shares, crop yields, animal stocking densities and fertilizer
application rates to about 140 000 1x1 km pixel cluster and links
these results to a statistical meta model of the bio-physical model
DNDC.