Issues of Scale in Nested Integrated Assessment Models

Integrated assessment models have been used to explore cost effective abatement strategies in connection with negotiations on the Gothenburg protocol under the UN/ECE Convention on Long Range Transboundary Air Pollution (CLRTAP). A variety of spatial and temporal issues must be addressed in order to 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 the spatial characteristics of its' application to UK and European contexts, and identify the specific variations of the constituent models and data at each resolution. Encompassing NH3, SO2, NOX, particulates, O3 and VOCs, it is clear a n-IAM must capture dynamics both beyond and through the current scales implemented by the UKIAM and ASAM. Ammonia abatement becomes significant at the micro scale using non-technical measures and buffer zones, roadside NO2 is important at the urban scale, and the dynamics of O3 stretch from the urban scale to the hemispheric level, affecting the fates of VOCs and NOX. Timescales implicit in dispersion models and empirical data, together with multi-scalar effects and policy scenarios must be mapped, and methodological approaches to critical loads and ecosystem recovery must be captured. At the UK National Focal Centre for Integrated Assessment Modelling work is ongoing linking the European scale ASAM and the national scale UKIAM, and progress is being made in linking these to global and urban scale integrated assessment models.