Shelf seas in the temperate and arctic regions host unique ecosystems and are an essential source for life in the ocean as well as on the bordering terrestrial landmasses. They enable and facilitate a multitude of human activities, from tourism and ship traffic to the exploitation and exploration of food sources, energy and raw materials. Coastal shelf seas especially those in northern latitudes, are therefore becoming more and more part of our living habitat. This exploitation of the sea, as an extension of the terrestrial land use, even encompasses remote and unspoilt Polar Regions. Shelf seas not only transform anthropogenic riverine compounds, they also built important interfaces for global material cycles, e.g. through the uptake and emission of carbon compounds such as carbon dioxide (CO2) and methane (CH4). Thus these regions influence the system earth and, in turn, react on global change and related local human resource uses.

Current observations in the North Sea reveal drastic changes in biogeochemistry and food webs accompanied by the occurrence of new and the disappearance of established species occurs (see Figure). Neither causes nor consequences of these shifts are known. However, changes in physical climate (e.g., temperature, wind), atmospheric gases as well as human influences (e.g., over-fishing, species introduction) most probably act as major drivers. In the arctic regions strong erosion processes and increasing emissions of greenhouse gases are expected due to the thawing of permafrost soils and sediments. In those marine areas directly connected to the Atlantic current circulation increasing water temperatures and changing oceanic current patterns and intensities will affect the complex and sensitive interplay of physical, biological, chemical and geological processes. The dynamic behaviour of such complex systems is hardly understood and only partially documented, because long-term observations are almost lacking.

Scenarios of future development of the ecosystem North Sea and arctic shelf seas, which are a prerequisite for a sustainable management under human pressure, are based on the extrapolation of fragmented knowledge, on the analysis of present and past system states, as well as on a linked model based integrated process understanding. Numerical simulation models therefore play a decisive role in the construction and setup of scenarios. The reliability and credibility of model projections however depends to a large extent on the understanding of fundamental principles. Models of shelf seas lose validity and reliability without a steady correction through data from measurements, especially because of the extremely high variability in time and space as well as the limited descriptive power of state-of-the-art biogeochemical or ecological model parts. Fronts propagating along the coastal current dominated by tides, steep gradients perpendicular to the coastline, the openness of the system, in particular physical and biological extreme events (storm floods, massive algal blooms, anoxia), all cause hardly solved problems in both simulation- as well as observational systems. Existing or past monitoring activities generally comprise a strongly limited set of parameters, which are or have been measured during a relatively short time span. The longterm station Helgoland Roads (AWI-Helgoland) is a worldwide unique exception to this rule.

However, this station just represents a single point in space within a heterogeneous sea region what also complicates interpretation of data. High-frequency, long-term and spatially covering observations of the geo-ecological state of shelf and coastal environments are beyond the capacity of single institutes. This holds both on the national as well as the international level. Nevertheless, in some countries such as France, the UK and the USA nationwide initiatives have been put in place through a well-defined centralisation (e.g., coastal observatories along the US coast).

The consortium of German marine science institutes (KDM: Konsortium Deutsche Meeresforschung), established a few years ago, has recently recognized the need as well as the challenge to set up an operational, integrated observational system for the German shelf (KDM, 2007). Such a coastal observatory requires national and international cooperation, and should be used as a German contribution to international programmes such as COASTAL GOOS, GEOSS, GEOHAB and GMES. The observational approach will only work in a feasible way on the long-term if it relies on cost effective platforms and robust as well as economical sensor technologies.

In the recent Blue Book of the European Commission the Action plan considers four measures of direct relevance for this proposal: a European strategy for marine research, an integrated network for marine observation and monitoring, a European maritime observational- and data network and finally a strategy to mitigate the effects of climate change in costal regions. To all four measures we will deliver concrete contributions.