Human impacts and their interactions in the Baltic Sea region

Abstract

Abstract. Coastal environments, in particular heavily populated semi-enclosed marginal seas and coasts like the Baltic Sea region, are stongly affected by human activities. A multitude of human impacts, including climate change, affects the different compartments of the environment, and these effects interact with each other. As part of the Baltic Earth Assessment Reports (BEAR), we present an inventory and discussion of different human-induced factors and processes affecting the environment of the Baltic Sea region, and their interrelations. Some are naturally occurring and modified by human activities (i.e. climate change, coastal processes, hypoxia, acidification, submarine groundwater discharges, marine ecosystems, non-indigenous species, land use and land cover), some are completely human-induced (i.e. agriculture, aquaculture, fisheries, river regulations, offshore wind farms, shipping, chemical contamination, dumped warfare agents, marine litter and microplastics, tourism, coastal management), and they are all interrelated to different degrees. We present a general description and analysis of the state of knowledge on these interrelations. Our main insight is that climate change has an overarching, integrating impact on all of the other factors and can be interpreted as a background effect, which has different implications for the other factors. Impacts on the environment and the human sphere can be roughly allocated to anthropogenic drivers such as food production, energy production, transport, industry and economy. We conclude that a sound management and regulation of human activities must be implemented in order to use and keep the environments and ecosystems of the Baltic Sea region sustainably in a good shape. This must balance the human needs, which exert tremendous pressures on the systems, as humans are the overwhelming driving force for almost all changes we see. The findings from this inventory of available information and analysis of the different factors and their interactions in the Baltic Sea region can largely be transferred to other comparable marginal and coastal seas in the world.

Oceanographic regional climate projections for the Baltic Sea until 2100

“…In the early 21st century, about 85 million people, in 14 countries, were living in the catchment area, representing a considerable anthropogenic pressure for the marine ecosystem (HELCOM, 2018). Insufficiently treated wastewater, emissions of pollutants, overfishing, habitat degradation, and intensive marine traffic such as oil transports put a heavy burden on the ecosystem of the Baltic Sea (Reckermann et al, 2021). One example is the oxygen depletion of the Baltic Sea deep water, with the consequence of dead sea bottoms lacking higher forms of life (e.g., Carstensen et al, 2014;Meier et al, 2018b).…”

Coupled regional Earth system modeling in the Baltic Sea region

“…In turn, ice motion generates fractures and leads on the ice pack which enhance mobility and, more importantly, increase the sea-ice mean thickness owing to new ice growth in leads and the formation of pressure ridges in compression. Due to ice dynamics, the mean ice thickness in the coastal boundary zone is thicker than in landfast ice regions (Oikkonen et al, 2017;Ronkainen et al, 2018). The mobility of pack ice has large consequences regarding the formation of coastal leads, which are local sources of heat and moisture.…”

“…The current discharge models applied in coupled (or Earth system) models for global or regional climate simulations usually do not fulfill this requirement. In global ESMs, discharge (or routing) models are frequently part of the coupled system (often as part of the land surface scheme), but their spatial resolution is usually 0.5 • (Roeckner et al, 2003;Guimberteau et al, 2012) or coarser (Lawrence et al, 2011;Milly et al, 2014;Best et al, 2011).…”

“…Sein et al (2015 introduced the RCSM ROM in which the global ocean-sea-ice-marine biogeochemistry model MPIOM/HAMOCC with regionally high horizontal resolution is coupled to the atmospheric RCM REMO and the global HD model (see above) via the OASIS coupler. They used forcing from the NCEP/NCAR reanalysis and ECHAM5/MPIOM (Roeckner et al, 2003;Jungclaus et al, 2006) historical simulations and evaluated their results for the North Atlantic and North European region, where they also specifically addressed the Baltic Sea catchment.…”

“…The Baltic Earth program (https://www. baltic-earth.eu/, 10 September 2021), which brings together climate and environmental scientists around the Baltic Sea, emphasizes the importance of realistic coupled modeling to achieve an improved Earth system understanding of the Baltic Sea region, with "Multiple drivers for regional Earth system changes" being one of the "Grand Challenges" addressed by the program (Reckermann et al, 2021). (Cornes et al, 2018).…”