Issues of Scale in Nested Integrated Assessment Models

Integrated assessment models have been used to explore cost effective abatement strategies inconnection with negotiations on the Gothenburg protocol under the UN/ECE Convention on Long RangeTransboundary Air Pollution (CLRTAP). A variety of spatial and temporal issues must be addressed in orderto model the multi-scalar processes involved and develop nested Integrated Assessment Models (n-IAM)useful both for further protocol negotiations and to address inter-relationships between local air quality,transboundary air pollution and climate change. We summarise the generic framework, highlighting thespatial characteristics of its' application to UK and European contexts, and identify the specific variations ofthe constituent models and data at each resolution. Encompassing NH3, SO2, NOX, particulates, O3 andVOCs, it is clear a n-IAM must capture dynamics both beyond and through the current scales implemented bythe UKIAM and ASAM. Ammonia abatement becomes significant at the micro scale using non-technicalmeasures and buffer zones, roadside NO2 is important at the urban scale, and the dynamics of O3 stretch fromthe urban scale to the hemispheric level, affecting the fates of VOCs and NOX. Timescales implicit indispersion models and empirical data, together with multi-scalar effects and policy scenarios must bemapped, and methodological approaches to critical loads and ecosystem recovery must be captured. At theUK National Focal Centre for Integrated Assessment Modelling work is ongoing linking the European scaleASAM and the national scale UKIAM, and progress is being made in linking these to global and urban scaleintegrated assessment models.