River catchment–coastal sea interaction and human dimensions

The regional or local perspective of coastal change becomes increasingly important when coastal people are recognised as an integral part of the system. As pointed out in this journal (Cramer 2002), the key to improved interdisciplinary science of global change is not only to provide answers to the crucial Earth-system questions at a global scale. We also need to identify meaningful ways to look at the human environment and its changes at scales that are appropriate to identify choke and switch points for system functions, and where institutional settings enable action to be taken as a societal and policy response. For coastal zones, three major challenges need to be met by an appropriate and flexible scientific approach to this problem (cf. Kremer et al. 2002). First, the time delay between changes in land-based material flows (due to socioeconomic activities, morphological changes or regulatory measures) and their impact on the coastal zone system must be determined. Second, the complexity of the coastal sea environments needs to be investigated in order to derive assessments of ‘critical loads’. Third, multiple interests and stakeholder needs must be studied, as they are affected by transboundary issues, particularly when local, regional, national and multinational governmental bodies have conflicting interests. The Land-Ocean Interactions in the Coastal Zone (LOICZ) core project of the International Geosphere and Biosphere Program (IGBP), after 10 years of collaborative global research, has made an effort to follow this direction. Its ‘Basins project’ (http://w3g.gkss.de/projects/loicz_basins/) has, since 1999, tried to provide a first-order global assessment of key land-based processes that affect coastal zones. Regional scientific networks have been established to look at the drivers, pressures, state changes and the impact on coastal systems by applying a scale that