The conference topics are based on the Baltic Earth scientific Grand Challenges. Interdisciplinary contributions and contributions dealing with the "Multiple drivers" topic of the conference, including the role of humans, are especially welcome. In addition, we welcome such contributions from other coastal sea regions around the world, e.g. NOSCCA (North Sea Region Climate Change Assessment), HyMeX (Hydrological cycle in the Mediterranean Experiment), the Black Sea, or the "The four seas" initiative (comparing the Chinese Bo Hai and Huang Hai as well as the Baltic and North Sea regions). A special emphasis may also may be on the southern Baltic Sea coasts.
Conference topics are:
1. Salinity dynamics (provisional conveners: Andreas Lehmann, Kai Myrberg, Piia Post)
Salinity is an elementary factor controlling the ecosystems of the Baltic Sea. The long-term salinity dynamics is controlled by net precipitation, river runoff and the compensating inflow of higher saline waters from the Kattegat. The present understanding of salinity changes is still very limited, and future projections of the salinity evolution are rather uncertain. Due to the expected increase in precipitation, first studies of future development indicate even 2‐3 PSU decrease in salinity to the end of the century. Since the Baltic Sea ecosystem has adapted to the present salinity regime, expected changes would exert an enormous stress on marine fauna and flora with associated negative social-economic consequences for the Baltic Sea countries.
On an annual timescale, highly saline inflows (MBIs) that are able to replace the stagnant bottom waters in the deep basins of the Baltic Sea play a major role to ventilate hypoxic deep waters. Since the early eighties the frequency of highly saline inflows has dropped drastically from 5 to 7 events to only one inflow per decade. After more than 10 years without major inflows, in December 2014 a strong MBI occurred.
This session will focus on processes relevant for the salinity dynamics of the Baltic Sea. Contributions focusing on exchange processes between the North Sea and Baltic Sea including MBIs and associated atmospheric forcing conditions as well as studies concentrating on the fate of the inflowed water masses are highly welcome.
2. Land-Sea-Atmosphere biogeochemical coupling (provisional conveners: Gregor Rehder, Karol Kulinski, Benjamin Smith)
The biogeochemical functioning of the Baltic Sea is subject to vital changes including eutrophication, acidification, and deoxygenation. A wealth of experimental data and sophisticated model tools is available for the Baltic Sea, yet there is a lack of understanding in some fundamental processes and their proper parameterizations in biogeochemical modelling.
The processes occurring within the drainage area greatly influence the functioning of the Baltic Sea ecosystem. First of all, runoff from land affects the Baltic Sea salinity, with large impacts on the underlying physical processes. Moreover, riverine and other land-derived runoff supplies the Baltic with large amounts of different chemical substances. Crucial gaps still exist within the present databases, for example the lack of data from the Neva River, incidentally the largest river entering the Baltic Sea. For other, in particular recently developing chemical substances (e.g. pharmaceuticals) the terrestrial loads entering the Baltic Sea are insufficiently described. This holds also true for non-riverine fluxes from land. For instance, no integrated assessment of submarine groundwater seepage exists, despite the importance on biogeochemistry on regional scale is acknowledged. Large knowledge gaps exist with respect to transport, transformation and modification between the catchment region, the coastal zone and the inner basins of the Baltic Sea.
On the other hand, the pathways of several key substances also remain poorly constrained after entering the marine system. The description of the carbon system, both inorganic and organic, as a key variable for the Baltic Sea biogeochemistry, has only recently become a focus of biogeochemical modelling, and has not been appropriately covered in the environmental monitoring of the Baltic in the past. The potential decoupling of carbon uptake and inorganic nutrient availability is also a major uncertainty in the causal link of eutrophication and sub-halocline oxygen content, as the major oxygen demand during remineralization of organic matter is caused by the oxidation of organic carbon.
The extent and variability of oxygenated and anoxic bottom waters play a pivotal role in the reflux of nutrients and carbon from the sediments. Major uncertainties still exist in the understanding of the retention of nutrients, carbon, and a variety of other substances in the sediments and their controls, in particular under changing oxygenation levels. These internal elemental loops need better quantification and model parameterization.
3. Natural hazards and high impact events (provisional conveners: Jari Haapala, Anna Rutgersson, Martin Stendel)
Extreme (or high-impact) events and natural hazards have a major impact on society. Such events include storms, flooding, droughts, blizzards, but also events with ecosystem extremes (as algae blooms). Many natural hazards have hydrometeorological origins (storms, waves, flooding, droughts) and can potentially be better understood. Natural hazards are often complex phenomena (storm surge + heavy precipitation → excess runoff → extreme flooding). During the last ten years, society has become more sensitive to the environmental hazards, and weather related losses have increased.
Moreover, climate change can change the occurrence and intensity of extreme events and lead to even larger hazards in the Baltic Sea region. The scientific challenge is to improve predictability of extreme events in synoptic, seasonal and climatic scales. This session will focus on how hydrological, oceanographic and meteorological extremes have changed historically but also on the response of marine ecosystems to extreme events (coastal processes), and the carbon cycle in response to changes in extreme conditions, how they are projected to change in the future, and what the likely impacts on society will be.
4: Sea level dynamics, coastal morphology and erosion (provisional conveners: Eduardo Zorita, Inga Dailidiene, Birgit Hünicke)
The global mean sea level shows large variations at regional scales, which are reflected in the very heterogeneous pattern of sea‐level trends in the last 30 years. The still present large uncertainties in future global sealevel are thus magnified when considering regional scenarios for sea‐level change. So far, no comprehensive scenarios for future sea‐level rise in the Baltic Sea exist. The complex bathysphere of the Baltic Sea and the influence of the North Sea and the Baltic Sea catchment area represent specific challenges for the predictions of sea‐level rise that are distinct from the global average.
Suggested key research areas are a compilation of large long‐time series from written records, in particular for gauges, the analysis of satellite data sets and comparison with coastal station data in the period of overlap, identification of the locally resolved multi‐decadal variability and centennial trends of the rate of sea‐level rise, a regionalization of sea‐level scenarios by analyses of AR5 CMIP5 scenarios +scenarios of land‐ice dynamics, a combination of this information with recent knowledge about land movement, storm surges and wave conditions to evaluate the impact on the coasts, and the identification of the major physical and socio‐economic mechanisms that may in the future endanger the stability of the coastlines beyond the range of its natural variability.
In addition, impacts related to rising sea level (and related stronger storm surges) on coastal morphology and erosion shall be treated in this session.
5. Regional variability of water and energy exchanges (provisional conveners: Irina Partasenok, Sergej Zhuravlev, Sirje Keevallik)
The understanding of the water and energy exchanges in the Baltic Sea region still suffers from severe shortcomings, ranging from insufficient observations and a lack of process understanding to modelling problems. Contributions are welcome related to the following aspects:
- the observation of atmospheric processes, respectively the characterization of measurement uncertainties for Atmospheric Boundary Layer processes as well as for atmospheric processes, the observation of atmospheric exchange processes from surface to top of atmosphere at different climate scales for various spatial scales
- the diagnosis of natural variability of energy and water components, which includes the quantification of changes in extremes and the determination of probabilities of their occurrences (for the last century up to now);
- the improved description and modelling of atmospheric processes with up-to-date atmospheric and Earth-system models to simulate the regional/local energy and water cycle with parameterizations considering e.g. an improved understanding of cloud-aerosol-feedback mechanisms, of cloud processes and of atmospheric boundary layer processes;
- the extended and continuous evaluation of atmospheric processes with conventional meteorological/hydrological observations, with surface based and satellite based remote sensing to ensure the best possible prediction of water and energy exchanges in the Baltic Sea drainage basin; and
- the modelling/prediction of short- and long-term water and energy exchanges of the past century and of the future century to provide a significant service to the people of the Baltic Sea region.
6. Regional climate system modeling (provisional conveners: Markus Meier, Corinna Schrum, NN)
This topic aims at the understanding of regional energy, momentum, water, and matter fluxes and their effects on the regional climate using observations and Regional Climate System Models (RCSMs) encompassing processes in the atmosphere, land, sea, and anthroposphere. In recent years, coupled atmosphere – sea ice – ocean models have been elaborated further by using a hierarchy of sub-models for the Earth system, combining regional climate models with sub-models for surface waves, land vegetation, hydrology, land and marine biogeochemistry, the marine carbon cycle as well as marine biology and food webs. Hence, there is a tendency to develop so-called regional Earth system models with the aim to investigate the impact of climate change on the entire terrestrial and marine environment.
Studies on the following aspects are encouraged to be presented: development and evaluation of regional climate system models (coupled atmosphere – ice – ocean – land surface/vegetation – biogeochemical/carbon – food web models), regional process studies and studies on the added value of coupled models with high resolution, studies of extreme or high impact events using coupled models, climate change impact studies and uncertainty assessments of projections using coupled model simulations.
7. Multiple and interrelated drivers of environmental changes (provisional conveners: Anders Omstedt, Hans von Storch, NN)
The environmental changes we observe are caused by a mixture of interwoven factors, among them climate change and its impacts, eutrophication, pollution, fisheries and land cover change. Each of these factors has a scientific and a societal dimension, which are often interdependent, and which makes the identification of a single or even dominant factor responsible for the change difficult. The scope of this thematic block is to describe the different factors for change, their impacts on the Earth system of the Baltic Sea region, and to demonstrate the capacity to model any of these factors in a single or a coupled approach. Are we able to simulate the observed changes in a realistic way? Are we able to produce credible scenarios for the future? Ultimately, this analysis should help to identify knowledge gaps and research needs for the coming years, to help find solutions for the challenges we face in the future.
This is a cross-cutting topic reflecting the overall topic of the 1st Baltic Earth conference and has relations to all the other topics and Grand Challenges.