Climate change and the Baltic Sea action plan: Model simulations on the future of the western Baltic Sea

2012 ◽  
Vol 105-108 ◽  
pp. 175-186 ◽  
Author(s):  
René Friedland ◽  
Thomas Neumann ◽  
Gerald Schernewski
Keyword(s):  
Climate Change ◽  
Baltic Sea ◽  
Action Plan ◽  
The Baltic Sea ◽  
Model Simulations ◽  
The Future ◽  
The Baltic

A combination of species distribution and ocean-biogeochemical models suggests that climate change overrides eutrophication as the driver of future distributions of a key benthic crustacean in the estuarine ecosystem of the Baltic Sea

2020 ◽  
Vol 77 (6) ◽  
pp. 2089-2105
Author(s):  
Mayya Gogina ◽  
Michael L Zettler ◽  
Irene Wåhlström ◽  
Helén Andersson ◽  
Hagen Radtke ◽  
...  
Keyword(s):  
Climate Change ◽  
Baltic Sea ◽  
Action Plan ◽  
Future Climate Change ◽  
Suitable Habitat ◽  
Nutrient Loads ◽  
The Baltic Sea ◽  
Estuarine Ecosystem ◽  
Biogeochemical Models ◽  
The Baltic

Abstract Species in the brackish and estuarine ecosystems will experience multiple changes in hydrographic variables due to ongoing climate change and nutrient loads. Here, we investigate how a glacial relict species (Saduria entomon), having relatively cold, low salinity biogeographic origin, could be affected by the combined scenarios of climate change and eutrophication. It is an important prey for higher trophic-level species such as cod, and a predator of other benthic animals. We constructed habitat distribution models based occurrence and density of this species across the entire Baltic and estimated the relative importance of different driving variables. We then used two regional coupled ocean-biogeochemical models to investigate the combined impacts of two future climate change and nutrient loads scenarios on its spatial distribution in 2070–2100. According to the scenarios, the Baltic Sea will become warmer and fresher. Our results show that expected changes in salinity and temperature outrank those due to two nutrient-load scenarios (Baltic Sea Action Plan and business as usual) in their effect on S. entomon distribution. The results are relatively similar when using different models with the same scenarios, thereby increasing the confidence of projections. Overall, our models predict a net increase (and local declines) of suitable habitat area, total abundance and biomass for this species, which is probably facilitated by strong osmoregulation ability and tolerance to temperature changes. We emphasize the necessity of considering multiple hydrographic variables when estimating climate change impacts on species living in brackish and estuarine systems.

Climate change and recovery from eutrophication reduce benthic fauna and carbon processing in a coastal sea

2020 ◽  
Author(s):  
Eva Ehrnsten ◽  
Alf Norkko ◽  
Bärbel Müller-Karulis ◽  
Erik Gustafsson ◽  
Bo Gustafsson
Keyword(s):  
Climate Change ◽  
Baltic Sea ◽  
Coastal Ecosystems ◽  
Benthic Macrofauna ◽  
Combined Effects ◽  
Nutrient Loads ◽  
The Baltic Sea ◽  
The Future ◽  
The Baltic ◽  
Carbon Processing

<p>Nutrient loading and climate change affect coastal ecosystems worldwide. Unravelling the combined effects of these pressures on benthic macrofauna is essential for understanding the future functioning of coastal ecosystems, as it is an important component linking the benthic and pelagic realms. In this study, we extended an existing model of benthic macrofauna coupled with the physical-biogeochemical BALTSEM model of the Baltic Sea to study the combined effects of changing nutrient loads and climate on biomass and metabolism of benthic macrofauna historically and in scenarios for the future. Based on a statistical comparison with a large validation dataset of measured biomasses, the model showed good or reasonable performance across the different basins and depth strata in the model area. In scenarios with decreasing nutrient loads according to the Baltic Sea Action Plan, but also with continued recent loads (mean loads 2012-2014), overall macrofaunal biomass and carbon processing were projected to decrease significantly by the end of the century despite improved oxygen conditions at the seafloor. Climate change led to intensified pelagic recycling of primary production and reduced export of particulate organic carbon to the seafloor with negative effects on macrofaunal biomass. In the high nutrient load scenario, representing the highest recorded historical loads, climate change counteracted the effects of increased productivity leading to a hyperbolic response: biomass and carbon processing increased up to mid-21<sup>st</sup> century but then decreased, giving almost no net change by the end of the 21<sup>st</sup> century compared to present. The study shows that benthic responses to environmental change are nonlinear and partly decoupled from pelagic responses and indicates that benthic-pelagic coupling might be weaker in a warmer and less eutrophic sea.</p>

Projections for Temperature, Precipitation, Wind, and Snow in the Baltic Sea Region until 2100

2018 ◽  
Author(s):  
Ole Bøssing Christensen ◽  
Erik Kjellström
Keyword(s):  
Climate Change ◽  
Wind Speed ◽  
Baltic Sea ◽  
Climate Models ◽  
Global Climate Models ◽  
Anthropogenic Climate Change ◽  
The Baltic Sea ◽  
Baltic Sea Region ◽  
The Future ◽  
The Baltic

The ecosystems and the societies of the Baltic Sea region are quite sensitive to fluctuations in climate, and therefore it is expected that anthropogenic climate change will affect the region considerably. With numerical climate models, a large amount of projections of meteorological variables affected by anthropogenic climate change have been performed in the Baltic Sea region for periods reaching the end of this century.Existing global and regional climate model studies suggest that:• The future Baltic climate will get warmer, mostly so in winter. Changes increase with time or increasing emissions of greenhouse gases. There is a large spread between different models, but they all project warming. In the northern part of the region, temperature change will be higher than the global average warming.• Daily minimum temperatures will increase more than average temperature, particularly in winter.• Future average precipitation amounts will be larger than today. The relative increase is largest in winter. In summer, increases in the far north and decreases in the south are seen in most simulations. In the intermediate region, the sign of change is uncertain.• Precipitation extremes are expected to increase, though with a higher degree of uncertainty in magnitude compared to projected changes in temperature extremes.• Future changes in wind speed are highly dependent on changes in the large-scale circulation simulated by global climate models (GCMs). The results do not all agree, and it is not possible to assess whether there will be a general increase or decrease in wind speed in the future.• Only very small high-altitude mountain areas in a few simulations are projected to experience a reduction in winter snow amount of less than 50%. The southern half of the Baltic Sea region is projected to experience significant reductions in snow amount, with median reductions of around 75%.

scholarly journals Global climate change and the Baltic Sea ecosystem: direct and indirect effects on species, communities and ecosystem functioning

2021 ◽  
Author(s):  
Markku Viitasalo ◽  
Erik Bonsdorff
Keyword(s):  
Climate Change ◽  
Baltic Sea ◽  
Food Web ◽  
Experimental Work ◽  
Ecosystem Functioning ◽  
The Baltic Sea ◽  
Food Web Dynamics ◽  
The Future ◽  
Modelling Studies ◽  
The Baltic

Abstract. Climate change has multiple direct and indirect potentially synergistic effects on Baltic Sea species, organism communities, and on ecosystem functioning, through physical and biogeochemical environmental characteristics of the sea. Associated indirect and secondary effects on species interactions, trophic dynamics and ecosystem function are expected to be significant. Evidence on effects of climate are compiled from and reviewed for field studies, experimental work, as well as modelling studies primarily from published literature after 2010. The responses vary within and between species groups, even between sibling species. Such subtle differences, as well as secondary feedbacks and altered trophic pathways, make projections difficult. Some common patterns arise from the wealth of recent studies, however. It is likely that the combined effects of increased external nutrient loads, stratification and internal loading will improve the conditions for cyanobacterial blooms in large parts of the Baltic. In the northernmost areas the increasing allochtonous DOM may further complicate the picture by increasing heterotrophy and by decreasing food web efficiency. This effect may, however, be counteracted by the intensification of the bacteria-flagellate-microzooplankton-mesozooplankton link, which may change the system from a bottom-up controlled one to a top-down controlled one. In deep benthic communities, continued eutrophication may promote higher sedimentation of organic matter and increase zoobenthic biomasses, but eventually increasing stratification and hypoxia/anoxia will disrupt benthic-pelagic coupling, leading to reduced benthic biomass. In the photic benthic systems warmer winters with less ice and nutrient increase enhances eutrophication. The projected salinity decline suppresses marine species, and temperature increase overgrowth of perennial macroalgae by annual filamentous alga throughout the growing-season, and major changes in the marine entire ecosystem are expected. The changes in environmental conditions probably also lead to increased establishment of non-indigenous species, potentially affecting food web dynamics in large areas of the Baltic Sea. However, several modelling studies have concluded that nutrient reductions according to the Baltic Sea Action Plan of Helsinki Commission may be a stronger driver for ecosystem functions in the Baltic Sea than climate change. Such studies highlight the importance of studying the Baltic Sea as an interlinked socio-ecological system. Knowledge gaps include uncertainties in projecting the future salinity level as well as stratification under different climate forcings. This weakens our ability to project how overall biodiversity, pelagic productivity, fish populations, and macroalgal communities may change in the future. Experimental work must be better integrated into studies of food web dynamics, to get a more comprehensive view of the responses of the pelagic and benthic systems to climate change, from bacteria to fish. Few studies have holistically investigated the shallow water ecosystems holistically. There are complex climate-induced interactions and multiple feedbacks between algae, grazers and their predators, that are poorly known, as are the effects of non-native invasive species. Finally, both 2D species distribution models and 3D ecosystem models could benefit from better integration of approaches including physical, chemical and biological parameters.

scholarly journals Coupled regional Earth system modelling in the Baltic Sea region

2021 ◽  
Author(s):  
Matthias Gröger ◽  
Christian Dieterich ◽  
Jari Haapala ◽  
Ha Thi Minh Ho-Hagemann ◽  
Stefan Hagemann ◽  
...  
Keyword(s):  
Climate Change ◽  
Baltic Sea ◽  
Regional Climate ◽  
Model Systems ◽  
Earth System ◽  
The Baltic Sea ◽  
Coupled Models ◽  
Baltic Sea Region ◽  
Ocean Models ◽  
The Baltic

Abstract. Non-linear responses to externally forced climate change are known to dampen or amplify the local climate impact due to complex cross compartmental feedback loops in the earth system. These feedbacks are less well represented in traditional standalone atmosphere and ocean models on which many of today's regional climate assessments rely on (e.g. EuroCordex, NOSCCA, BACC II). This promotes the development of regional climate models for the Baltic Sea region by coupling different compartments of the earth system into more comprehensive models. Coupled models more realistically represent feedback loops than the information imposed into the region by using prescribed boundary conditions, and thus, permit a higher degree of freedom. In the past, several coupled model systems have been developed for Europe and the Baltic Sea region. This article reviews recent progress of model systems that allow two way communication between atmosphere and ocean models, models for the land surface including the terrestrial biosphere, as well as wave models at the air sea interface and hydrology models for water cycle closure. However, several processes that have so far mostly been realized by one way coupling such as marine biogeochemistry, nutrient cycling and atmospheric chemistry (e.g. aerosols) are not considered here.Compared to uncoupled standalone models, coupled earth system models models can modify mean near surface air temperatures locally up to several degrees compared to their standalone atmospheric counterparts using prescribed surface boundary conditions. Over open ocean areas, the representation of small scale oceanic processes such as vertical mixing, and sea ice dynamics appear essential to accurately resolve the air sea heat exchange in the Baltic Sea region and can only be provided by online coupled high resolution ocean models. In addition, the coupling of wave models at the ocean-atmosphere interface allows a more explicit formulation of small-scale to microphysical processes with local feedbacks to water temperature and large scale processes such as oceanic upwelling. Over land, important climate feedbacks arise from dynamical terrestrial vegetation changes as well as the implementation of land use scenarios and afforestation/deforestation that further alter surface albedo, roughness length and evapotranspiration. Furthermore, a good representation of surface temperatures and roughness length over open sea and land areas is critical for the representation of climatic extremes like e.g. heavy precipitation, storms, or tropical nights, and appear to be sensitive to coupling.For the present-day climate, many coupled atmosphere-ocean and atmosphere-land surface models demonstrate added value with respect to single climate variables in particular when low quality boundary data were used in the respective standalone model. This makes coupled models a prospective tool for downscaling climate change scenarios from global climate models because these models often have large biases on the regional scale. However, the coupling of hydrology models for closing the water cycle remains problematic as the accuracy of precipitation provided by the atmosphere models is in most cases insufficient to realistically simulate the runoff to the Baltic Sea without bias adjustments.Many regional standalone ocean and atmosphere models are tuned to well represent present day climatologies rather than accurately simulate climate change. More research is necessary about how the regional climate sensitivity (e.g. the models’ response to a given change in global mean temperature) is affected by coupling and how the spread is altered in multi-model and multi-scenario ensembles of coupled models compared to uncoupled ones.

scholarly journals Human impacts and their interactions in the Baltic Sea region

2021 ◽  
Author(s):  
Marcus Reckermann ◽  
Anders Omstedt ◽  
Tarmo Soomere ◽  
Juris Aigars ◽  
Naveed Akhtar ◽  
...  
Keyword(s):  
Climate Change ◽  
Baltic Sea ◽  
Human Activities ◽  
Human Impacts ◽  
The Other ◽  
Indigenous Species ◽  
General Description ◽  
The Baltic Sea ◽  
Baltic Sea Region ◽  
The Baltic

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.

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