Research Area 2: Coastal Seas in Transition:
Present, Past & Future Perspectives
Our coastal seas are no static systems. The Baltic Sea, for example, has - since the last glaciation - been subject to natural fluctuations as response to variations in basin geometry and climate over the course of decades, centuries and millennia. Only by recognising this natural variability and all its implications, we can identify the human-made changes of the Late Holocene and particularly the Anthropocene, which superimpose the natural background. With joint forces, we will work on two overarching topics, which thematically require the application of various IOW disciplines. These are the expansion of our long-term observation programme and modelling activities to hotspot areas of climate change response: the Northern Baltic and the shallow water regions, and the reconstruction of past ecosystem conditions to inform the future. For details see Box 2.
Expanding our long-term observation programme and modelling activities in the Baltic Sea to hotspot areas of climate change response: the Northern Baltic and the shallow water regions
The long-term observation programme is one of the centrepieces of our research: on 5 cruises per year important environmental parameters are recorded at different water depths on a fixed network of stations that extends into the central Gotland Basin. The resulting data show the variability of these parameters on a yearly scale as well as trends on the decadal scale. This programme enabled the recognition of the rapid warming of the Baltic Sea surface waters and suggested recently accelerated oxygen consumption rates despite overall decreasing nutrient inputs, to name just two examples of the outcome. It is an essential backbone for our hydrodynamic and ecosystem modelling work as well as for many different applied projects investigating the impact of anthropogenic activities and climate change. For the coming years, we want to expand our joint activities on observations and modelling into two regions: the northern Baltic Sea, undergoing drastic changes due to the reduction in seasonal ice cover, and the shallow water areas, which will be particularly vulnerable to extreme events like heat waves, or storm flood.
Reconstructing past ecosystem conditions to inform the future
To achieve high quality climate and environmental reconstructions at as highly resolved as seasonal time-scales and to couple these results with model simulations for interglacial periods such as the Holocene, we need a collaborative effort among sedimentologists, geochemists, paleoceanographers, biologists, and modelers. The linkage of proxy-based estimations with monitoring observations and hindcast simulations together with a precise depositional chronology will enable us to recognize the timing and rate at which climate and ecosystem shifts occurred in the past. It will permit synchronizing local sediment records with regional and global records in order to evaluate the dynamics, mechanisms, and patterns involved in climate and environmental changes on a hemispheric and even planetary scale. To this end, it will be essential to include the North Atlantic, the key region of climate variability in northern Europe, to understand the link between the different North Atlantic variability patterns (AMV, NAO, AMOC) and the Baltic Sea region in the past and the future.
Box 2: Research area (RA) 2 emphasises on topics, requiring concerted multidisciplinary efforts.
In general, we identified research needs in four subtopics. The first three of them are: The present state of the Baltic Sea system, the reconstruction of past ecosystem conditions and future projections under changing climate & human impact. With the onset of the Anthropocene, any Earth system research has to include humankind as an important factor of influence. Beside the multitude of negative impacts leading to the triple planetary crisis of climate change, pollution and biodiversity loss, humankind is also an actor when it comes to mitigation and restoration measures. These aspects are highlighted under the fourth subtopic Shaping the coastal sea´s future.