Baltic Earth Working Group on "Teleconnection between the North Atlantic and Northern Europe and the Baltic Sea region"

Backgrounds and objective

Climate change is happening across the globe. However, its manifestation has different effects in different areas of the world. Some places will warm much more than others; some regions will experience increased precipitation or severe droughts. There is an increasing interest in evaluating the regional impacts of climate change and understanding how these may vary for different socio-economic pathways.

On a global scale, it is a well-proven technique to assess the impact of a changing climate using large model ensembles. An ensemble mean usually outperforms the individual model in global metrics of climate. However, models disagree more often when applying regional metrics and show larger variance. Sometimes they predict changes of opposite signs, such as a change in
precipitation over smaller regions.

The north European continent has dynamic linkages to the polar climate of the Arctic in the North, the temperate maritime climate of the North Atlantic in the West, and the continental climate with increased seasonality in the East.
Among others, climate change impacts in Northern Europe and the Baltic Sea region have been linked to variability in the jet stream and storm tracks, ultimately related to changes in meridional temperature and pressure gradients. Also, the North Atlantic Oscillation, the most important binary mode of climate variability during winter, manifests itself over the North Atlantic. Moreover, very recently, the North Atlantic Ocean was identified as an essential driver of climate variability in the Baltic Sea region.

With the recently published BEAR reports and the work of the CLIMSEA project, there is already a downscaled ensemble of regional climate simulations. However,
until now, there has yet to be a particular focus on the linkage between the North Atlantic and Northern Europe on different timescales. Furthermore, in the previous decades, the number of different global and regional atmospheric reanalysis products significantly grew, and some went back into the past for more than 100 years. Thus, it is now possible to study low-frequency climate

This working group will primarily focus on the teleconnection between the North Atlantic, Northern Europe, and the Baltic Sea.

Descriptions of the tasks (Terms of reference)

- Assessing the quality of CMIP6 global simulations that will be used for the dynamic downscaling in the Baltic Sea region
- Investigating global data sets, such as ERA-20C or ERSST, to identify energy and mass transports to the Baltic Sea catchments
- Climate predictability & forecasts for Northern Europe - Develop regional criteria for Northern Europe based on large-scale climate processes, such as storm tracks, blocking events, and ocean-atmosphere interaction in the North Atlantic
- How does dynamically driven climate variability (e.g., jet stream) with its origin far outside the Baltic Sea propagate on its pathway to the Baltic Sea?
- Control of the North Atlantic and other critical remote regions on the Baltic Sea from synoptic to decadal/centennial time scales
- Identification of critical regions with teleconnections to the Baltic Sea. Are there early indicators for climate change out of the Baltic?
- How will atmospherically mass and energy flow over Europe change, and what are the impacts on the Baltic Sea(/catchment)?

Expected outcome

- Review paper – Identify the lack of knowledge
- Assessment of global GCMs that are best for our region
- Conducting impact studies (relax global model towards AMV+ and AMVstates)
- Storyline paper for the Baltic Sea
- Workshop/session at the next Baltic Earth

Duration of this working group: 3 year


Florian Börgel (
Matthias Gröger (