scholarly journals Uncertainties in Projections of the Baltic Sea Ecosystem Driven by an Ensemble of Global Climate Models

2019 ◽  
Vol 6 ◽  
Author(s):  
Sofia Saraiva ◽  
H. E. Markus Meier ◽  
Helén Andersson ◽  
Anders Höglund ◽  
Christian Dieterich ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Climate Models ◽  
Global Climate ◽  
Global Climate Models ◽  
The Baltic Sea ◽  
The Baltic

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%.

Representative climate projections for the North Sea and Baltic Sea

2021 ◽  
Author(s):  
Christian Dieterich ◽  
Matthias Gröger ◽  
Anders Höglund ◽  
Renate A. I. Wilcke ◽  
H. E. Markus Meier
Keyword(s):  
Climate Change ◽  
Model Selection ◽  
Baltic Sea ◽  
Model Uncertainty ◽  
Climate Model ◽  
Global Climate ◽  
Global Climate Models ◽  
Climate Projections ◽  
The Baltic Sea ◽  
The Baltic

<p>Robust estimations of uncertainty for climate projections on the regional scale are highly needed but are still challenging. Regional climate projections rely on downscaling global climate scenarios. Typically, a number of different global climate models are downscaled to assess the inherent model uncertainty. The more models, the more robust the estimate of model uncertainty. However, this strategy is time consuming and so ensembles of regional projections are usually smaller than ensembles of global projections which can lead to an underestimation of regional uncertainty. With an increasing number of available global projections regional downscaling becomes increasingly expensive. We use a regional ensemble of coupled atmosphere-ice-ocean scenarios and a ensemble of ocean-ecosystem scenarios for the Baltic Sea to explore the effect of model selection on the representation of model uncertainty. Using a number of climate indices to characterize the regional system we apply a model selection that is representative of the original ensemble in terms of ensemble spread. We use existing algorithms to generate orthogonal patterns of climate change for the Baltic Sea. A small number of patterns is used to represent the climate change and its uncertainty in physical and biogeochemical parameters of the Baltic Sea. We show that climate change signals in atmosphere, ocean and ecosystem are coherent and that atmospheric or oceanic indices can be used to select global climate models for an ensemble of representative regional ecosystem scenarios for the Baltic Sea. Since the atmospheric climate in the regional climate model is close to its representation in the global climate model that latter can be used to perform an initial model selection.</p>

Regional Climate Modeling for the Baltic Sea Region

2020 ◽  
Author(s):  
Erik Kjellström ◽  
Ole Bøssing Christensen
Keyword(s):  
Climate Change ◽  
Baltic Sea ◽  
Climate Models ◽  
Climate Modeling ◽  
Regional Climate ◽  
Regional Climate Modeling ◽  
Sea Surface ◽  
The Baltic Sea ◽  
Baltic Sea Region ◽  
The Baltic

Regional climate models (RCMs) are commonly used to provide detailed regional to local information for climate change assessments, impact studies, and work on climate change adaptation. The Baltic Sea region is well suited for RCM evaluation due to its complexity and good availability of observations. Evaluation of RCM performance over the Baltic Sea region suggests that: • Given appropriate boundary conditions, RCMs can reproduce many aspects of the climate in the Baltic Sea region. • High resolution improves the ability of RCMs to simulate significant processes in a realistic way. • When forced by global climate models (GCMs) with errors in their representation of the large-scale atmospheric circulation and/or sea surface conditions, performance of RCMs deteriorates. • Compared to GCMs, RCMs can add value on the regional scale, related to both the atmosphere and other parts of the climate system, such as the Baltic Sea, if appropriate coupled regional model systems are used. Future directions for regional climate modeling in the Baltic Sea region would involve testing and applying even more high-resolution, convection permitting, models to generally better represent climate features like heavy precipitation extremes. Also, phenomena more specific to the Baltic Sea region are expected to benefit from higher resolution (these include, for example, convective snowbands over the sea in winter). Continued work on better describing the fully coupled regional climate system involving the atmosphere and its interaction with the sea surface and land areas is also foreseen as beneficial. In this respect, atmospheric aerosols are important components that deserve more attention.

scholarly journals Impact of change in climate and policy from 1988 to 2007 on environmental and microbial variables at the time series station Boknis Eck, Baltic Sea

2013 ◽  
Vol 10 (7) ◽  
pp. 4529-4546 ◽  
Author(s):  
H.-G. Hoppe ◽  
H. C. Giesenhagen ◽  
R. Koppe ◽  
H.-P. Hansen ◽  
K. Gocke
Keyword(s):  
Time Series ◽  
Baltic Sea ◽  
Global Climate ◽  
Time Lag ◽  
Vertical Mixing ◽  
Bacterial Biomass ◽  
Glucose Turnover ◽  
Positive Trend ◽  
The Baltic Sea ◽  
The Baltic

Abstract. Phytoplankton and bacteria are sensitive indicators of environmental change. The temporal development of these key organisms was monitored from 1988 to the end of 2007 at the time series station Boknis Eck in the western Baltic Sea. This period was characterized by the adaption of the Baltic Sea ecosystem to changes in the environmental conditions caused by the conversion of the political system in the southern and eastern border states, accompanied by the general effects of global climate change. Measured variables were chlorophyll, primary production, bacteria number, -biomass and -production, glucose turnover rate, macro-nutrients, pH, temperature and salinity. Negative trends with time were recorded for chlorophyll, bacteria number, bacterial biomass and bacterial production, nitrate, ammonia, phosphate, silicate, oxygen and salinity while temperature, pH, and the ratio between bacteria numbers and chlorophyll increased. Strongest reductions with time occurred for the annual maximum values, e.g. for chlorophyll during the spring bloom or for nitrate during winter, while the annual minimum values remained more stable. In deep water above sediment the negative trends of oxygen, nitrate, phosphate and bacterial variables as well as the positive trend of temperature were similar to those in the surface while the trends of salinity, ammonia and silicate were opposite to those in the surface. Decreasing oxygen, even in the surface layer, was of particular interest because it suggested enhanced recycling of nutrients from the deep hypoxic zones to the surface by vertical mixing. The long-term seasonal patterns of all variables correlated positively with temperature, except chlorophyll and salinity. Salinity correlated negatively with all bacterial variables (as well as precipitation) and positively with chlorophyll. Surprisingly, bacterial variables did not correlate with chlorophyll, which may be inherent with the time lag between the peaks of phytoplankton and bacteria during spring. Compared to the 20-yr averages of the environmental and microbial variables, the strongest negative deviations of corresponding annual averages were measured about ten years after political change for nitrate and bacterial secondary production (~ −60%), followed by chlorophyll (−50%) and bacterial biomass (−40%). Considering the circulation of surface currents in the Baltic Sea we interpret the observed patterns of the microbial variables at the Boknis Eck time series station as a consequence of the improved management of water resources after 1989 and – to a minor extent – the trends of the climate variables salinity and temperature.

scholarly journals Impact of change in climate and policy from 1988 to 2007 on environmental and microbial variables at the time series station Boknis Eck, Baltic Sea

2012 ◽  
Vol 9 (12) ◽  
pp. 18655-18706 ◽  
Author(s):  
H.-G. Hoppe ◽  
H. C. Giesenhagen ◽  
R. Koppe ◽  
H.-P. Hansen ◽  
K. Gocke
Keyword(s):  
Time Series ◽  
Baltic Sea ◽  
Global Climate ◽  
Time Lag ◽  
Vertical Mixing ◽  
Bacterial Biomass ◽  
Glucose Turnover ◽  
Positive Trend ◽  
The Baltic Sea ◽  
The Baltic

Abstract. Phytoplankton and bacteria are sensitive indicators of environmental change. The temporal development of these key organisms was monitored from 1988 to the end of 2007 at the time series station Boknis Eck in the Western Baltic Sea. This period was characterized by the adaption of the Baltic Sea ecosystem to changes in the environmental conditions caused by the collapse and conversion of the political system in the Southern and Eastern Border States, accompanied by the general effects of global climate change. Measured variables were chlorophyll, primary production, bacteria number, -biomass and -production, glucose turnover rate, macro-nutrients, pH, temperature and salinity. Negative trends with time were recorded for chlorophyll, the bacterial variables, nitrate, ammonia, phosphate, silicate, oxygen and salinity while temperature, pH, and the ratio between bacteria numbers and chlorophyll increased. The strongest reductions with time occurred for the annual maximum values, e.g. for chlorophyll during the spring bloom or for nitrate during winter, while the annual minimum values remained more stable. In deep water above sediment the negative trends of oxygen, nitrate, phosphate and bacterial variables as well as the positive trend of temperature were similar to those in the surface while the trends of salinity, ammonia and silicate were opposite to those in the surface. Decreasing oxygen even in the surface layer was of particular interest because it suggested enhanced recycling of nutrients from the deep hypoxic zones to the surface by vertical mixing. In the long run all variables correlated positively with temperature, except chlorophyll and salinity. Salinity correlated negatively with all bacterial variables as well as precipitation and positively with chlorophyll. Surprisingly, bacterial variables did not correlate with chlorophyll which may be inherent with the time lag between the peaks of phytoplankton and bacteria during spring. Compared to the 20-yr averages of the environmental and microbial variables, the strongest negative deviations of corresponding annual averages were measured about ten years after political change for nitrate and bacterial secondary production (~ −60%), followed by chlorophyll (−50%) and bacterial biomass (−40%). Considering the circulation of surface currents in the Baltic Sea we conclude that the improved management of water resources after 1989 together with the trends of the climate variables salinity and temperature were responsible for the observed patterns of the microbial variables at the Boknis Eck time series station.

scholarly journals Uncertainties in projections of the Baltic Sea ecosystem driven by an ensemble of global climate models

2018 ◽  
Author(s):  
Sofia Saraiva ◽  
H. E. Markus Meier ◽  
Helén Andersson ◽  
Anders Höglund ◽  
Christian Dieterich ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Greenhouse Gas Emissions ◽  
Greenhouse Gas ◽  
General Circulation ◽  
Climate Models ◽  
Greenhouse Gas Emission ◽  
Nutrient Load ◽  
The Baltic Sea ◽  
Gas Emissions ◽  
The Baltic

Abstract. Many coastal seas worldwide are affected by human impacts such as eutrophication, causing, inter alia, oxygen depletion and extensive areas of hypoxia. Depending on the region, global warming may reinforce these environmental changes by reducing air–sea oxygen fluxes, intensifying internal nutrient cycling and increasing river-borne nutrient loads. The development of appropriate management plans to more effectively protect the marine environment requires projections of future marine ecosystem states. However, projections with regional climate models commonly suffer from shortcomings in the driving global General Circulation Models (GCMs). The differing sensitivities of GCMs to increased greenhouse gas emissions impact regional projections considerably. In this study, we focused on one of the most threatened coastal seas, the Baltic Sea, and estimated uncertainties in projections due to GCM deficiencies relative to uncertainties caused by future greenhouse gas emissions and nutrient load scenarios. To address the latter, transient simulations of the period 1975–2098 were performed using the initial conditions from an earlier reconstruction with the same Baltic Sea model (starting in 1850). To estimate the impacts of GCM deficiencies, dynamical downscaling experiments with four driving global models were carried out for two greenhouse gas emission scenarios, RCP4.5 and 8.5, and for three nutrient load scenarios covering the plausible range between low and high loads. The results of primary production, nitrogen fixation, and hypoxic areas show that uncertainties caused by the various nutrient load scenarios are greater than the uncertainties due to global model deficiencies and future greenhouse gas emissions. In all scenario simulations, a proposed nutrient load abatement strategy, i.e., the Baltic Sea Action Plan, will lead to a significant improvement in the overall environmental state. However, the projections cannot provide detailed information on the timing and the reductions of future hypoxic areas due to uncertainties in salinity projections caused by uncertainties in projections of the regional water cycle and of the global mean sea level rise.

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