It has been shown that regional climate change interacts with many other man-made perturbations in both natural and anthropogenic coastal environments. Regional climate change is one of multiple drivers, which have a continuing impact on terrestrial, aquatic and socio-economic (resp. human) environments. These drivers interact with regional climate change in ways, which are not completely understood. Recent assessments all over the world have partly addressed this issue (e.g. Assessment of Climate Change for the Baltic Sea region, BACC (2008, 2015); North Sea Climate Change Assessment, NOSCCA (2011); Canada’s Changing Climate Report, CCCR (2019)).
This session invites contributions, which focus on the connections and interrelations between climate change and other drivers of environmental change, be it natural or human-induced, in different regional seas and coastal regions. Observation and modelling studies are welcome, which describe processes and interrelations with climate change in the atmosphere, in marine and freshwater ecosystems and biogeochemistry, coastal and terrestrial ecosystems as well as human systems. In particular, studies on socio-economic factors like aerosols, land cover, fisheries, agriculture and forestry, urban areas, coastal management, offshore energy, air quality and recreation, and their relation to climate change, are welcome.
The aim of this session is to provide an overview over the current state of knowledge of this complicated interplay of different factors, in different regional seas and coastal regions all over the world.

Co-organized by BG4/HS12/NH10/OS2
Convener: Marcus Reckermann | Co-conveners: Ute Daewel, Helena Filipsson, Markus Meier, Markus Quante
| Attendance Thu, 07 May, 16:15–18:00 (CEST)

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Chat time: Thursday, 7 May 2020, 16:15–18:00

Chairperson: Marcus Reckermann
D2532 |
Samaneh Seifollahi-Aghmiuni, Zahra Kalantari, and Georgia Destouni

Eutrophication and water quality issues in the Baltic Sea and its coastal zones have strong human dimensions, including also land and water uses and their management in hinterland areas. Solutions require participatory approaches to inspire integrated long-term ‘land-sea’ systems management, and contribute to the development of harmonized guidelines at different spatial scales. Considering the source to sea case of Swedish Norrström drainage basin, its surrounding coastal areas, and the associated marine basin of the Baltic Sea, this study has used a participatory approach to enhance understanding of the land-sea system links and dynamics, and facilitate exploration of cross-system/sector cooperation opportunities for addressing water-related high-impact issues, including water pollution and eutrophication. Employing a problem-oriented system thinking approach, we investigate the following questions based on various sector perspectives in the study region: (i) What are the key underlying land-sea system elements and their interlinkages? (ii) What are the most relevant and important dynamics for evaluation of land-sea system behavior? and (iii) What are the main challenges and opportunities for sustainable coastal management and development? Different groups of relevant stakeholders are asked to co-create causal loop diagrams for characterizing the land-sea system dynamics based on their perceptions of and answers to the questions (i)-(iii). From the co-created causal loop diagrams, sector-specific and general issues, challenges, opportunities, and barriers to sustainable coastal development in the study region are identified. In further analysis, various scenarios of the land-sea system dynamics and the importance of feedback mechanisms are investigated. The scenario results and associated system behavior are also validated by stakeholders. Selected scenarios are further quantified by systems dynamics modeling, exploring the impacts of associated coastal development and policy options on the regional water-related issues and potential sustainable solutions. The scenario analysis outcomes highlight the necessity and usefulness of combining scientific knowledge with local expertise for synergistic and strategic planning of sustainable coastal region development.

How to cite: Seifollahi-Aghmiuni, S., Kalantari, Z., and Destouni, G.: Understanding the coupled land-sea system dynamics in coastal regions through a participatory approach: A Baltic case study, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4603, https://doi.org/10.5194/egusphere-egu2020-4603, 2020.

D2533 |
Alena Bartosova, René Capell, Jørgen E. Olesen, and Berit Arheimer

The Baltic Sea is suffering from eutrophication caused by nutrient discharges from land to sea. These freshwater inflows vary in magnitude from year to year as well as within each year due to e.g. natural variability, weather patterns, and seasonal human activities. Nutrient transport models are important tools for assessments of macro-nutrient fluxes (nitrogen, phosphorus) and for evaluating the connection between pollution sources and the assessed water body. While understanding of current status is important, impacts from changing climate and socio-economics on freshwater inflows to the Baltic Sea also need to be taken into account when planning management practices and mitigation measures.

Continental to global scale catchment-based hydrological models have emerged in recent years as tools e.g. for flood forecasting, large-scale climate impact analyses, and estimation of time-dynamic water fluxes into sea basins. Here, we present results from the pan-European rainfall-runoff and nutrient transfer model E-HYPE, developed as a multi-purpose tool for large-scale hydrological analyses. We compared current freshwater inflows from land with those from dynamic modelling with E-HYPE under various climate and socioeconomic conditions. The socioeconomic conditions (land use, agricultural practices, population changes, dietary changes, atmospheric deposition, and wastewater technologies) were evaluated for 3 additional time horizons: 2050s using the Shared Socioeconomic Pathways, 1900s using historical data, and a reference period using a synthetic “no human impact” scenario. An ensemble of 4 climate models that preserves the range of projected changes in precipitation and temperature from a larger ensemble was selected for analysis of climate impacts in 2050s.  

We show that while climate change affects nutrient loads to the Baltic Sea, these impacts can be overshadowed by the impacts of changing socioeconomic factors. Historical nitrogen loads were estimated as 43% and 33% of the current loads for the 1900s and the “no human impact” scenarios, respectively. Average nitrogen loads are projected to increase by 4-10% (8% on average) as a response to climate change by 2050s. Purely mitigation measures that did not address the magnitude of the nutrient sources reduced the total nitrogen load by <5%, with local efficiencies being reduced through retention processes. However, changes in the socioeconomic drivers led to significant changes in the future loads with the range of impacts spanning 30% of the current load depending on the socioeconomic pathway to be followed. This means that policy decisions have by far the largest impact when managing eutrophication in the Baltic Sea region.

Bartosova, A., Capell, R., Olesen, J.E. et al. (2019). Future socioeconomic conditions may have a larger impact than climate change on nutrient loads to the Baltic Sea. Ambio 48, 1325–1336 doi:10.1007/s13280-019-01243-5

How to cite: Bartosova, A., Capell, R., Olesen, J. E., and Arheimer, B.: Past, current, and future freshwater inflows to the Baltic Sea under changing climate and socioeconomics, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9882, https://doi.org/10.5194/egusphere-egu2020-9882, 2020.

D2534 |
Birte-Marie Ehlers, Frank Janssen, and Janna Abalichin

The “German Strategy for Adaption to Climate Change” (DAS) has been established as the political framework to climate change adaption in Germany. One task of the “Adaption Action Plan of the DAS” is the installation of a permanent service of seamless climate prediction. The pilot project “Projection Service for Waterways and Shipping” (ProWaS) prepares an operational forecasting and projection service for climate, extreme weather and coastal and inland waterbodies. The target region is the North Sea and Baltic Sea with focus on the German coastal region and its estuaries.

ProWaS provides regional model setups for the North and Baltic Seas. To figure out technical issues and to validate the model setups, 20-year hindcast simulations forced with a regional reanalysis (COSMO-REA6 (Bollmeyer et al., 2015)) were carried out.

These simulations are used as basis for sensitivity studies with reference to global change scenarios. To evaluate the effect of global changes on the coastal regions especially in the North and Baltic Seas, model studies regarding global sea level rise, changes in global ocean and air temperature, changes in global salinity and changes of the regional river runoffs have been performed. Therefore, boundary conditions of a hindcast simulation are adapted to different change conditions and sensitivity studies for different periods have been carried out. First results of these investigations on model sensitivity studies are presented. These results will be used as a basis for further development of climate projection models.

How to cite: Ehlers, B.-M., Janssen, F., and Abalichin, J.: First results of model sensitivity studies on the influence of global changes to the North and Baltic Seas, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21520, https://doi.org/10.5194/egusphere-egu2020-21520, 2020.

D2535 |
Claudia Gabriela Mayorga Adame, James Harle, Jason Holt, Artioli Yuri, and Sarah Wakelin

Climate change is expected to cause important changes in ocean physics, which will in turn have important effects on the marine ecosystems. The ReCICLE project (Resolving Climate Impacts on shelf and CoastaL seas Ecosystems) aims to identify and quantify the envelope of response to climate change of lower trophic level shelf-sea ecosystems and their functional interactions, in order to assess the vulnerability of ecosystem goods and services in the UK shelf seas. The central tool for this work is an ensemble of coupled hydrodynamic-biogeochemical ecosystem models NEMO-ERSEM Atlantic Margin Model configuration at 7 km horizontal resolution (AMM7), forced by different CIMP5 global climate change models to generate downscaled scenarios for future decades.

Changes in connectivity patterns are expected to affect coastal populations of marine organisms in shelf seas. Holt et al 2018 (GRL https://doi.org/10.1029/2018GL078878) showed the potential for radical reorganization of the North Sea circulation in earlier simulations. To assess this particular issue particle tracking experiments are carried out during two 10 year time slices, in the recent past (2000-2010) and in the future (2040-2050) in ensemble members of the ReCICLE AMM7 regional downscaling showing contrasting circulation patterns. Surface particles were uniformly seeded in the UK shelf seas every month and tracked for 30 days. The resulting particle trajectories are analysed with cluster analysis technics aiming to determine if persistent oceanographic boundaries re-arrange in the future climate scenarios. The ecological effects of circulation and water masses changes in the future ocean are discussed from a Lagrangian perspective.


How to cite: Mayorga Adame, C. G., Harle, J., Holt, J., Yuri, A., and Wakelin, S.: Climate change effects on UK shelf sea’s connectivity and hydrographic properties, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12403, https://doi.org/10.5194/egusphere-egu2020-12403, 2020.

D2536 |
Corinna Schrum, Naveed Akhtar, Nils Christiansen, Jeff Carpenter, Ute Daewel, Bughsin Djath, Martin Hieronymi, Burkhardt Rockel, Johannes Schulz-Stellenfleth, Larissa Schultze, and Emil Stanev

The North Sea is a world-wide hot-spot in offshore wind energy production and installed capacity is rapidly increasing. Current and potential future developments raise concerns about the implications for the environment and ecosystem. Offshore wind farms change the physical environment across scales in various ways, which have the potential to modify biogeochemical fluxes and ecosystem structure. The foundations of wind farms cause oceanic wakes and sediment fluxes into the water column. Oceanic wakes have spatial scales of about O(1km) and structure local ecosystems within and in the vicinity of wind farms. Spatially larger effects can be expected from wind deficits and atmospheric boundary layer turbulence arising from wind farms. Wind disturbances extend often over muliple tenths of kilometer and are detectable as large scale wind wakes. Moreover, boundary layer disturbances have the potential to change the local weather conditions and foster e.g. local cloud development. The atmospheric changes in turn changes ocean circulation and turbulence on the same large spatial scales and modulate ocean nutrient fluxes. The latter directly influences biological productivity and food web structure. These cascading effects from atmosphere to ocean hydrodynamics, biogeochemistry and foodwebs are likely underrated while assessing potential and risks of offshore wind.

We present latest evidence for local to regional environmental impacts, with a focus on wind wakes and discuss results from observations, remote sensing and modelling.  Using a suite of coupled atmosphere, ocean hydrodynamic and biogeochemistry models, we quantify the impact of large-scale offshore wind farms in the North Sea. The local and regional meteorological effects are studied using the regional climate model COSMO-CLM and the coupled ocean hydrodynamics-ecosystem model ECOSMO is used to study the consequent effects on ocean hydrodynamics and ocean productivity. Both models operate at a horizontal resolution of 2km.

How to cite: Schrum, C., Akhtar, N., Christiansen, N., Carpenter, J., Daewel, U., Djath, B., Hieronymi, M., Rockel, B., Schulz-Stellenfleth, J., Schultze, L., and Stanev, E.: Wind wake effects of large offshore wind farms, an underrated impact on the marine ecosystem?, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12932, https://doi.org/10.5194/egusphere-egu2020-12932, 2020.

D2537 |
Eva Ehrnsten, Alf Norkko, Bärbel Müller-Karulis, Erik Gustafsson, and Bo Gustafsson

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-21st century but then decreased, giving almost no net change by the end of the 21st 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.

How to cite: Ehrnsten, E., Norkko, A., Müller-Karulis, B., Gustafsson, E., and Gustafsson, B.: Climate change and recovery from eutrophication reduce benthic fauna and carbon processing in a coastal sea, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19063, https://doi.org/10.5194/egusphere-egu2020-19063, 2020.

D2538 |
Charlotte Marcinko, Andrew Harfoot, Tim Daw, Derek Clarke, Sugata Hazra, Craig Hutton, Chris Hill, Attila Lazar, and Robert Nicholls

The United Nations Sustainable Development Goals (SDGs) promote sustainable development and aim to address multiple challenges including those related to poverty, hunger, inequality, climate change and environmental degradation. Interlinkages between SDGS means there is potential for interactions, synergies and trade-offs between individual goals across multiple temporal and spatial scales. We aim to develop an Integrated Assessment Model (IAM) of a complex deltaic socio-ecological system where opportunities and trade-offs between the SDGs can be analysed. This is designed to inform local/regional policy. We focus on the Sundarban Biosphere Reserve (SBR) within the Indian Ganga Delta. This is home to 5.6 million often poor people with a strong dependence on rural livelihoods and also includes the Indian portion of the world’s largest mangrove forest – the Sundarbans. The area is subject to multiple drivers of environmental change operating at multiple scales (e.g. global climate change and sea-level rise, deltaic subsidence, extensive land use conversion and widespread migration). Here we discuss the challenges of linking models of human and natural systems to each other in the context of local policy decisions and SDG indicators. Challenges include linking processes derived at multiple spatial and temporal scales and data limitations. We present a framework for an IAM, based on the Delta Dynamic Emulator Model (ΔDIEM), to investigate the affects of current and future trends in environmental change and policy decisions within the SBR across a broad range of sub-thematic SDG indicators. This work brings together a wealth of experience in understanding and modelling changes in complex human and natural systems within deltas from previous projects (ESPA Deltas and DECCMA), along with local government and stakeholder expert knowledge within the Indian Ganga Delta.

How to cite: Marcinko, C., Harfoot, A., Daw, T., Clarke, D., Hazra, S., Hutton, C., Hill, C., Lazar, A., and Nicholls, R.: Synergies and trade-offs for the SDGs in a deltaic socio-ecological system: Development of an Integrated Assessment Model , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12312, https://doi.org/10.5194/egusphere-egu2020-12312, 2020.

D2539 |
| Highlight
Nils Christiansen, Ute Daewel, Corinna Schrum, Jeff Carpenter, Bughsin Djath, and Johannes Schulz-Stellenfleth

The production of renewable offshore wind energy in the North Sea increases rapidly, including development in ecologically significant regions. Recent studies identified implications like large-scale wind wake effects and mixing of the water column induced by wind turbines foundations. Depending on atmospheric stability, wind wakes imply changes in momentum flux and increased turbulence up to 70 km downstream, affecting the local conditions (e.g. wind speed, cloud development) near offshore wind farms. Atmospheric wake effects likely translate to the sea-surface boundary layer and hence influence vertical transport in the surface mixing layer. Changes in ocean stratification raise concerns about substantial consequences for local hydrodynamic and biogeochemical processes as well as for the marine ecosystem.
Using newly developed wind wake parametrisations together with the unstructured-grid model SCHISM and the biogeochemistry model ECOSMO, this study addresses windfarming impacts in the North Sea for future offshore wind farm scenarios. We focus on wind wake implications on ocean dynamics as well as on changes in tidal mixing fronts near the Dogger Bank and potential ecological consequences. At this, we create important knowledge on how the cross-scale wind farm impacts can be modelled suitably on the system scale.

How to cite: Christiansen, N., Daewel, U., Schrum, C., Carpenter, J., Djath, B., and Schulz-Stellenfleth, J.: Regional Impacts of Offshore Windfarming on the Hydro- and Ecosystem Dynamics in the North Sea, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7997, https://doi.org/10.5194/egusphere-egu2020-7997, 2020.

D2540 |
Fabian Werner, Ute Daewel, Stefan Hagemann, Rohini Kumar, Oldrich Rakovec, Michael Weber, Sabine Attinger, and Corinna Schrum

Regional climate change and anthropogenic activities are altering land-based freshwater runoff and nutrient loads to northern European shelf seas, which both leave their imprint on the hydrography and biogeochemistry of coastal ecosystems on annual to multi-decadal timescales. Long-term simulations forced by regional climate models have been proven as powerful tools to identify these impacts on the variability of the North Sea and Baltic Sea ecosystems. However, the simulations are prone to substantial biases concerning the land-sea coupling. Long-term river discharge forcing for regional ocean models usually needs to be compiled from different data sources and climatologies. Typically resulting in patchy, inconsistent datasets. Additionally, the contribution of smaller river catchments and day-to-day discharge variability is not adequately resolved. In this study, we used two novel high-resolution river runoff datasets to simulate 66-years ecosystem hindcasts with the 3D coupled physical-biogeochemical NPZD-model ECOSMO II, to study the role of river discharge forcing for the quality of the ecosystem simulation. The forcing datasets are based on consistent long-term reconstructions of the hydrological discharge model (HD) at 5 min. resolution and the mesoscale hydrological model (mHm) at 0.0625° resolution, both covering the entire northern European catchment region. We compare long-term seasonal and annual statistics of salinity, oxygen, inorganic nitrogen and phosphorus from the model simulations to those from a reference simulation with standard runoff, compiled from various data sources, and to those estimated from observations. Furthermore, potential bottom-up effects on lower-tropic-level dynamics are investigated, by comparatively analyzing long-term variability in phytoplankton biomass and primary production in model simulations forced by different runoff products.

How to cite: Werner, F., Daewel, U., Hagemann, S., Kumar, R., Rakovec, O., Weber, M., Attinger, S., and Schrum, C.: The added value of high-resolution river runoff forcing for simulating long-term ecosystem dynamics and biogeochemical cycling in northern European shelf seas, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21553, https://doi.org/10.5194/egusphere-egu2020-21553, 2020.

D2541 |
Sudeshna Kumar, Haimanti Banerji, and Biplab Kanti Sengupta

Kolkata’s city core is getting depopulated but has experienced an explosive population growth leading to rapid urbanization which is encroaching the ecologically fragile wetlands of the eastern fringe of the main city. This contrasting urban growth along the East Kolkata wetland is accounted mainly for the increase in city size, expansion of tertiary and service sector activities especially the IT boom, and the improved transit facilities along the eastern fringe. This has helped the real estate sector to thrive along the vulnerable eastern fringe of the city, leading to a drastic change in the wetland ecosystem. Secondary studies have also indicated that consumption of wetlands, indicated by fragmented land use has altered the microclimate of Kolkata. The significant land cover change due to human-induced perturbations has led to an insurgence of temperature in the region (Li, Mitra, Dong, & Yang, 2018). The entire transit corridor is subjected to verticalization juxtaposing the cultural essence of Kolkata bringing with it a myriad of Economic, Social, Cultural and subsequent planning challenges. The critical review of the selective literature shows how the best planning practices have integrated transit policies with land use. This has further helped the researcher in formulating strategies and policies specific to the regional context in order to render sustainable development in the study area. The study explores how the transit policies in Kolkata have actually transformed the city physically, socially, culturally and changed its microclimate. The study identifies future trends and assesses the future development potential, intensification with the help of qualitative and quantitative analysis. The study also conducts land suitability analysis for framing proposals and recommendations for ensuring sustainable development along the East Kolkata Wetland.  The outcome of this study is a methodology for sustainability strategic planning for developing the growth node along the eastern fringe of Kolkata which will curb the encroachment of the East Kolkata Wetlands. The study also provides a platform for policy recommendations for land use management and mitigate future climate changes in this eco-fragile zone.

Keywords: landuse; climate change; transit policies; sustainable planning; wetlands


Li, X., Mitra, C., Dong, L., & Yang, Q. (2018). Understanding land use change impacts on microclimate using Weather Research and Forecasting (WRF) model. Physics and Chemistry of the Earth, 103, 115–126. https://doi.org/10.1016/j.pce.2017.01.017

How to cite: Kumar, S., Banerji, H., and Kanti Sengupta, B.: Methodology for sustainable development along an eco-fragile zone for land use management and mitigating climate change: Evidence of East Kolkata Wetlands, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2080, https://doi.org/10.5194/egusphere-egu2020-2080, 2020.

D2542 |
Thomas Spencer and Susan Brooks

Shoreline retreat can happen rapidly in cliffs composed of loosely consolidated glacial and pre-glacial sediments. Typical centennial-scale average retreat rates for some cliffed coastlines of East Anglia, UK are 2 - 5 m a-1 where cliffs have no protection from storm energetics. Recent research using pre- and post-storm clifftop (geomorphological) surveys, as well as aerial photographs, has shown that in single events retreat can be 3 – 4 times the long-term average, with up to 15 m of retreat in a single event. Periods of clifftop stasis are thus interspersed with short term shocks, when meteorological conditions generate energetic drivers of change (elevated still water levels, high onshore waves, high rainfall inputs). Furthermore, short term shocks deliver enhanced sediment supply to the nearshore region, which is an important factor to take into account within future management planning strategies.  

This paper uses the latest Earth Observation data to quantify and evaluate rates of soft rock cliff retreat, thereby identifying periods when short term shocks have been delivered to the cliffs. It then explores the climate drivers of these shocks and assesses the associated synoptic meteorological scenarios. Finally it considers the implications for quantities of sediment released, in terms of both overall magnitude and alongshore variability.

Results suggest that three recent events stand out as having a significant impact on rates of cliff retreat and associated sediment release on the Suffolk coast, southern North Sea. The “Big Freeze” of the UK winter of 2010-11 involved a protracted period of easterly air flow from mid-November and into December, 2010. The process drivers were high magnitude onshore winds, generating nearshore waves of around 4 m. The 5 December 2013 North Sea surge similarly resulted in rapid cliff retreat and sediment release. In this event winds were alongshore so the wave impacts were lower, but the elevated water levels generated by the surge meant that wave action could be directed onto the cliffs. By far the biggest recent event in terms of storm forcing energetics was the February – March 2018 “Beast from the East” and “Mini Beast”, where persistent onshore winds generated waves of almost 4.5 m at Southwold Approaches (highest on record) that coincided with two phases of high spring tides (no surge). When regional-scale Sudden Stratospheric Warming (SSW) generates strong and persistent easterly winds there are widespread potentially irreversible consequences for cliff and beach sediments around the western North Sea coastline.

How to cite: Spencer, T. and Brooks, S.: Soft rock cliff retreat under changing climate drivers, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8183, https://doi.org/10.5194/egusphere-egu2020-8183, 2020.

D2543 |
Jens Möller, Ina Teutsch, and Ralf Weisse

Rogue waves are a potential threat for both shipping and offshore structures like wind power stations or oil platforms. While individual Rogue waves are short-lived and almost unpredictable, there is a chance to predict the probability of the occurrence of freak waves in conjunction with different weather types. The German Ministry of Transport and digital Infrastructure has tasked its Network of Experts to investigate the possible evolutions of extreme threats for shipping and offshore wind energy plants in the German Bight, the south-eastern part of the North Sea near the German coast.

In this study, we present an analysis from the co-occurrence of freak waves with different weather types in the German Bight in the past (from observations). In addition, we investigate potential changes of the occurrence of freak waves in the future due to a changing climate and changing appearance of the relevant weather types (by use of a coupled Regional Ocean-Atmosphere Climate Model, MPI-OM).

The investigation indicates a connection between the probability of the occurrence of freak waves at different stations and certain weather types. Potentially, this relationship could be used for warning crews of ships or offshore constructions. In a coupled Regional Ocean-Atmosphere Climate Model (MPI-OM) under scenario RCP8.5 we detect an increase of just such weather types, which are correlated with high waves, for the future.

How to cite: Möller, J., Teutsch, I., and Weisse, R.: Occurrence of Freak Waves in near-coast regions of the North Sea and their potential relationship with objective weather types , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9203, https://doi.org/10.5194/egusphere-egu2020-9203, 2020.

D2544 |
Yi-Ting Hsiao, Min-Hui Lo, and Hui-Yu Wang

   Tunas provide an important marine resource for the countries that surround the Pacific Ocean. Under climate change, climate models project an increasing frequency of central Pacific El Niño/Southern Oscillation events but a decreasing frequency of eastern Pacific El Niño/Southern Oscillation events, and may cause sea temperature rising in the central western Pacific relative to the eastern Pacific region and leading to corresponding changes in biological productivity, in turn influencing early life stage of tunas. Consequently, it is crucial to investigate how such climatic periodicity will impact the distribution and abundance of tunas.
   Here, yellowfin and albacore tunas are selected as our study species. Yellowfin tuna prefer warmer environments and have smaller body size and younger age-at-maturation (1 year) compared to albacore tunas (mature in 2 years). We use the spatially-explicit (5° grids) longline catch-and-effort data across 20°N~20°S and105°E~75°W,1970~2015, from Inter American Tropical Tuna Commission (IATTC) and Western & Central Pacific Fisheries Commission (WCPFC). We analyze the spatial and inter-annual variation in the catch-per-unit-effort for the two tunas with respect to changes in sea surface temperature in the central Pacific El Niño/Southern Oscillation events vs. the eastern Pacific El Niño/Southern Oscillation events. To investigate whether the distribution of tunas change under the central Pacific El Niño/Southern Oscillation events and the eastern Pacific El Niño/Southern Oscillation events will greatly help fisheries management and sustainable development of marine resources. 

How to cite: Hsiao, Y.-T., Lo, M.-H., and Wang, H.-Y.: Effects of sea surface temperature on distributions of two tropical tunas under the shifts of climate periodicity, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13315, https://doi.org/10.5194/egusphere-egu2020-13315, 2020.

D2545 |
Corinna Jensen, Jens Möller, and Peter Löwe

Within the “Network of experts” of the German Federal Ministry of Transport and Digital Infrastructure (BMVI), the effect of climate change on infrastructure is investigated. One aspect of this project is the future dewatering situation of the Kiel Canal (“Nord-Ostsee-Kanal” (NOK)). The Kiel Canal is one of the world’s busiest man-made waterways navigable by seagoing ships. It connects the North Sea to the Baltic Sea and can save the ships hundreds of kilometers of distance. With a total annual sum of transferred cargo of up to 100 million tons it is an economically very important transportation way. Additionally to the transportation of cargo, the canal is also used to discharge water from smaller rivers as well as drainage of a catchments area of about 1500 km².

The canal can only operate in a certain water level range. If its water level exceeds the maximum level, the water must be drained into the sea. In 90% of the time, the water is drained into the North Sea during time windows with low tide. If the water level outside of the canal is too high, drainage is not possible and the canal traffic has to be reduced or, in extreme cases, shut down. Due to the expected sea level rise, the potential time windows for dewatering are decreasing in the future. With a decrease in operational hours, there will be substantial economic losses as well as an increase in traffic around Denmark.

To get a better understanding of what causes tense dewatering situations other than sea level rise a linkage between high water levels on the outside of the canal and weather types is made. Weather types describe large-scale circulation patterns and can therefore give an estimate on tracks of low-pressure systems as well as the prevailing winds, which can explain surges and water levels at the coast. This analysis is conducted for one weather type classification method based solely on sea level pressure fields. Weather types derived from regionally coupled climate models as well as reanalyses are investigated.

How to cite: Jensen, C., Möller, J., and Löwe, P.: Linking weather types to tense dewatering situations of the Kiel Canal (NOK), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18083, https://doi.org/10.5194/egusphere-egu2020-18083, 2020.

D2546 |
Teresa Drago, Rui Taborda, Sebastião Teixeira, Marcos Rosa, João Pedro Cascalho, Miriam Tuaty-Guerra, Maria José Gaudêncio, Jorge Gonçalves, Paulo Relvas, Erwan Garel, Luciano Júnior, Victor Henriques, Pedro Terrinha, Jorge Arteaga, and Ana Ramos

Artificial nourishment of sandy beaches using sediment from borrow areas located on the continental shelf is increasingly a recommended solution for reversing the erosion process that affects the coastal zone. However, the impact of sand extraction in the shelf and deposition on the beach on the benthic communities (structure and functioning) is still poorly known, contributing to the lack of information needed for the assessment of Descriptor 6 (Sea-floor integrity) of the Marine Strategy Framework Directive (MSFD).

The aim of this work is to evaluate the morphological and ecosystem impacts of sand extraction at the inner shelf, as well as the consequent impacts of sand deposition at the nourished beaches. In this context, short-term and long-term monitoring activities based on a multidisciplinary approach were implemented at new and former borrow areas located in the southern Portugal (Algarve) inner continental shelf and adjacent beaches. These activities include multibeam bathymetric surveys complemented by surface sediment sampling, wave and current measurements, and a fluorescent tracer-marked sand experiment. Moreover, benthic macrofauna composition and structure are being studied at borrow areas (former and new) and at the nourished beaches. The acquired data allow a first assessment of the recovery rates regarding the sea-bottom morphology and benthic communities, and contribute to a better understanding of the involved processes.

The authors would like to acknowledge the financial support FCT through project UIDB/50019/2020 – IDL and ECOEXA project (MAR-01.04.02-FEAMP-0016)

How to cite: Drago, T., Taborda, R., Teixeira, S., Rosa, M., Cascalho, J. P., Tuaty-Guerra, M., Gaudêncio, M. J., Gonçalves, J., Relvas, P., Garel, E., Júnior, L., Henriques, V., Terrinha, P., Arteaga, J., and Ramos, A.: Impacts of sand extraction and deposition on the ecosystem recovery rate in the southern coastal zone of Portugal, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19110, https://doi.org/10.5194/egusphere-egu2020-19110, 2020.

D2547 |
Indre Razbadauskaite Venske, Inga Dailidiene, Remigijus Dailide, Vitalijus Kondrat, Egle Baltranaite, and Toma Dabulevičienė

This part is one of the research components for the Ph.D. thesis of geographical sustainable consumption which analyzes the influence of daily household waste causing a significant increase in marine litter. According to the "Marine Litter Socio-economic" study typical items founded on urban beaches usually are bottle caps, plastic bags, plastic food containers, wrappers, and plastic cutlery. In general, 48% of marine litter is caused by household-related waste and 70% of marine litter are plastics in the Baltic Sea (UN Environment, 2017; Helcom, 2018ad).

The main aim of this socio-economic research part is to investigate consumer as a source of marine litter in the Baltic Sea (pilot: Lithuania). It combines both qualitative and quantitative methods. Eye-tracker assists in the analysis of gaze points data which is collected on the beach photos with marine litter (focus on macro litter). Semi-structured interviews provide more in-depth insights about consumer behavior and habits. 

Thus, the main goal of this research is to find out and introduce awareness-raising activities among consumers that minimize marine litter and prevent waste generation behavior. To sum up, it is interdisciplinary research that combines three different areas: physical geography, environmental protection, and marketing with a special focus on consumer behavior.

How to cite: Razbadauskaite Venske, I., Dailidiene, I., Dailide, R., Kondrat, V., Baltranaite, E., and Dabulevičienė, T.: Consumer as a source of marine litter: Eye-tracking research in Baltic Sea coastal area , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21248, https://doi.org/10.5194/egusphere-egu2020-21248, 2020.

D2548 |
Nikolaus Groll

Wave hindcasts are still required as improved knowledge of climate variables representing the present marine climate are needed. Most long regional wave hindcasts are driven by numerically downscaled wind fields from global reanalysis. Whereas this approach gives a good representation of the regional wave climate in general, there are some deficits in the characteristics of extreme events. Using regional atmospheric reanalysis, which assimilates atmospheric observations into the numerical model, a better description of extreme events is expected. The regional atmospheric reanalysis COSMO-REA6 from the German Weather Service (DWD) showed that it is capable of a better representation of atmospheric extreme events. For the new regional wave hindcast, covering the North Sea and the Baltic Sea, we use the COSMO-REA6 to force the wave model WAM. It is shown, that his new wind hindcast leads to an improved representation of extreme wave events compared to other regional wave hindcasts and thus supports an important contribution to the understanding of the wave climate of extremes and for the design phase of offshore activities.

How to cite: Groll, N.: A new wave hindcast for the North and Baltic Sea region using COSMO-REA6 , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17713, https://doi.org/10.5194/egusphere-egu2020-17713, 2020.

D2549 |
Kristi Uudeberg, Mirjam Randla, Age Arikas, Tuuli Soomets, Kaire Toming, and Anu Reinart

Climate change is expected to continue in the 21st century, but the magnitude of change depends on future actions. In the Baltic Sea, specifically in the Pärnu Bay region, this is predicted to mean warmer temperatures, less ice cover, more precipitations and a slight increase in average wind speed, furthermore extreme climatic events such as heavy rains, strong winds and storms will be more intense and frequent. The coastal waters play a central role in humans and nature's everyday lives as providing food, living and recreational opportunities. Since Pärnu Bay is one of the most eutrophied area in the Baltic Sea and provides living hood more the 800 fishermen, then regular monitoring is strongly recommended, but with traditional methods often unfeasible. The availability of free Sentinel satellites data with good spectral, spatial and temporal resolution has generated wide interest in how to use remote sensing capabilities to monitor coastal waters water quality, which affects the underwater light field and can lead even to changes in fish composition. However, these waters are optically complex and influenced independently by coloured dissolved organic matter, phytoplankton and an amount of suspended sediments. Therefore, the remote sensing of optically complex waters is more challenging, and standard remote sensing products often fail. In this study, we use satellite Sentinel-3 data to investigate weather phenomena as strong wind and precipitations effect to Pärnu Bay water quality parameters. We study the spatial and temporal scope of change of water quality parameters after the event. For that, we use optical water type classification based chlorophyll-a, suspended sediments and coloured dissolved organic matter algorithms on Sentinel-3 images and estimate underwater light field changes. Furthermore, we also use in situ data to analyses the frequency and the strength of weather events. Finally, we look at the composition of fish based on literature and we investigate the possible effects of the change of the underwater light field on fish composition.

How to cite: Uudeberg, K., Randla, M., Arikas, A., Soomets, T., Toming, K., and Reinart, A.: Underwater light field changes in Pärnu Bay influenced by weather phenomena and captured by Sentinel-3, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19862, https://doi.org/10.5194/egusphere-egu2020-19862, 2020.

D2550 |
Fei Liu

The side-effect of booming urbanization on the ecosystem and climate system has been continuously exacerbating. The coastal metropolises are located at the interface between land and ocean, unavoidably influenced by multiple aspects of the terrestrial environments, aquatic ecosystems, and urban developments. Thus, the environmental health of coastal metropolis should be more concerned. In this study, targeting Guangzhou, Hangzhou, and Shanghai, an attempt was made to evaluate the spatiotemporal patterns and variations of surface urban heat island (SUHI) in three coastal metropolises of China based on Landsat-derived land surface temperatures (LST) and land cover data. The results indicate that overall, within a nearly 15-year interval, the extents of hot spots in three metropolises were significantly expanded, the spatial patterns of SUHI have been transformed from monocentric to polycentric high-LST clusters, which were identical to the trend of urban expansion. However,  these three metropolises possess distinct features in terms of the thermal layouts and land cover/use composition. Although the total area of SUHI hot spots in Shanghai has surged, the intensity of some hot spots has been a shrink. Besides, the interactions and associations between SUHI and urban development were investigated using spatial regression analysis. The urban composition and configuration considerably affected the intensity of SUHI. Terrain morphology constrained the SUHI. Prolific population growth had a continuing effect on SUHI formation. The proportion of forests displayed a consistently critical influence on easing the adverse of SUHI. Additionally, it is essential to appropriately consider the impacts of water in the comparative analysis of different thermal environments. However, water might be treated as a time-invariant factor and have a limited effect on the bi-temporal comparison for each metropolis. These findings suggest the policy-makers and urban planners should balance and optimize the land cover/use configurations with accommodating the increasing population, reasonably maximize the reservations of the greenbelt and green space under improving the utilization of urban infrastructures and constructions.

How to cite: Liu, F.: Bi-temporal Monitoring the Spatial Pattern and Variations of the Surface Urban Heat Island in three Chinese Coastal Megacities: A Comparative Study of Guangzhou, Hangzhou, and Shanghai., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19922, https://doi.org/10.5194/egusphere-egu2020-19922, 2020.