Note on Driving Forces and Emissionsf. The RAINS model relies on data from external bodies: countries, semi-official bodies, and others. These data sets can have a very limited overlap and so a large degree of operational flexibility is required to reconcile them. On the whole the RAINS team have operational procedures designed to check that emission data are as free from omission, error and material misstatement as currently possible15. These procedures place emphasis on dialogue with countries to reconcile aggregated results, understand the causes of differences, and bring about data convergence. Even given the poor quality of current ammonia and particulate inventories it is unlikely that the current emission estimates account for significant unidentified bias in the RAINS output. Estimates of future activity levels are problematic. IIASA relies on systems such as PRIMES and CAPRI and the accuracy of these inputs to RAINS is, to a large extent, outside the IIASA/RAINS sphere of influence. The largest errors/misstatements probably reside in the scenario related data from these external bodies – consequently the underlying energy and agricultural scenarios are part of bilateral discussions between IIASA and the countries. While it is sensible for IIASA to import some of the RAINS components (e.g. in the form of accepting scenarios from PRIMES and CAPRI) such externally created scenarios may have a decisive impact on projected emissions and abatement cost curves. This impact is especially important since it leaves national governments and their experts – who might verify those cost curves - with even greater uncertainty in the Model’s robustness. As a consequence limited knowledge of activity is likely to be the largest source of potential error/misstatement in the RAINS output. The emission calculation algorithm in RAINS is a variant of the one used by countries to calculate and report national emissions but it has been modified to allow for the introduction of certain types of abatement techniques16; the IIASA team are aware of the potential for bias that might result and works, via bilateral discussions, to reconcile any differences between RAINS calculated emissions and emissions reported by countries. The RAINS algorithm is technically sound as it is currently used17 but it is not ideally suited to non-technical abatement options. The bias likely to result from taking national emissions as reported by countries but taking natural emissions from EMEP, each with their own – differing – pro...
