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process must be clarity and rigour, and this is difficult, if not impossible to ensure if it is
several thousand lines of poor programming.
4. For a well-programmed model, there is a possibility of automating the conversion process.
However, this will almost certainly be incomplete, and need hand-crafting to finish.
5. It is worth remembering that programmed models (or submodels) can be wrapped up as a
black-box submodel in a declarative-modelling approach. This offers a transition strategy:
legacy models can be kept on in this form, to be gradually replaced by declarative reimplementations
over time.
If concern over the (assumed, but probably exaggerated) cost of translating existing models is a
significant issue - if it is seen as a sufficient reason to not embark on a declarative-modelling
approach - then we, as a community, really do need to consider whether we are prepared to
continue indefinitely with the present way of working, and to forgo the benefits of a superior
approach for short-term expediency.
9.4 Conclusions
A declarative modelling approach is not a magic bullet, which at a stroke removes the need for
person-years of effort in the ATEAM project. Considerable work is still required to condition the
scenario data sets to make them suitable for input into models, and to adapt models to fit into
ATEAM's 10' grid for Europe and 1-month/1-year time base. Apart from the possibility of
generating runnable versions of the models to run on high-performance computers, running
simulations would still be a computationally-demanding process, limiting the number of scenarios
that could be explored.
However, it would bring considerable benefits to a project such as ATEAM. Models could be
found, downloaded, adapted, linked to data and prepared for running simulations in the fraction of
the time. Generic tools, shared between the various ATEAM groups, would be available for
editing models, exploring their structure, benchmarking, validation and production runs. Most
importantly, non-researchers (stakeholders and policy-advisers) would be brought into the
modelling process in a way that is not possible with programming-implemented models.