Cluster Coastal and marine protection

The coastal regions are of particular socio-cultural, ecological and economic importance to Germany. Habitats in the intertidal zone between land and sea are unique and characterised by both high dynamics and great sensitivity. This zone is home to many rare animal and plant species. At the same time, the sea and adjacent coastal areas are of major economic importance. For example, the deep-sea fishing and fish-processing industries in coastal areas continue to be major employers (cf. ‘Fisheries’ action field). In addition, there is the maritime industry such as ship- and boatbuilding with its suppliers and service providers as well as marine and offshore technology including wind turbines. Coastal lowland areas are used for agricultural production. Not least, the high leisure and recreation value of coastal areas affords substantial opportunities to neighbouring communities for added value from tourism activities. The intensive utilisation exerts considerable pressure on the seas and the coastal regions. In many places the condition of the sea and adjacent coastal areas suffers from economic activities. The impacts of climate change entail additional burdens and challenges.

Seas are themselves massively affected by climate change. Global warming gives rise to extensive changes in ecosystems. At the same time, seas are CO₂ sinks, thus playing an important role in the protection from climate change.

Their storage, buffering and exchange functions give the Earth’s oceans a key role in its climate system. Especially in their deepest layers, the oceans store a major part of the additional amount of warmth caused by the anthropogenic greenhouse effect. However, the influence of rising air temperatures owing to climate change can also be measured at the water surface. For example, the mean warming of the North Sea water surface has been amounting to 0.26 °C per decade. The annual values are subject to natural fluctuations (cf. Indicator KM-I-1). The seas warming up has massive effects on the marine ecosystem. This is directly reflected, for instance, in a changed composition of the fish fauna (cf. Indicator FI-I-1) and in shrinking fish stocks in respect of individual fish species such as herring (cf. Indicator FI-I-2).

Another direct impact of heat storage in the ocean is the increase in seawater volume. This factor is a crucial cause of sea level rise. Both in the North Sea and the Baltic Sea, sea levels have been increasing in the course of recent decades (cf. Indicator KM-I-2). As far as coastal regions are concerned – in particular estuaries, coastal watercourses and lowlands that are partly below sea level – sea level rise without recourse to countermeasures is tantamount to increasing the risks involved. One of these risks is the danger of flooding due to storm surges as these can increase the height of the sea level to the same extent as mean sea level rise. Moreover, storm surges can – without a strong tidal flow – increase the volume of seawater being pushed up the watercourse where it flows into the sea, thus temporarily reversing the flow of the watercourse (cf. Indicator KM-I-5). However, the intensity and frequency of storm surges – both in the North Sea and the Baltic Sea – has not shown a distinct, unambiguous development in the course of roughly the past 150 years (cf. Indicator KM-I-3).

Very direct impacts are visible in terms of rising sea levels along the coastlines. When waves and storm surges increase in height as they break on the shore, they gain additional attack surface along the coastline. As a result, active cliffs recede faster, and coastal sections that were stable so far can begin to recede. This is indicated by a case study carried out in Mecklenburg-Western Pomerania, based on data from a representative segment of cliffscape on the peninsula of Fischland in the Baltic Sea (cf. Indicator KM-I-4). Owing to erosion, the cliffscape in this area has been shifted further inland by 20 to 40 centimetres every year. . Especially in years with frequent and major storm surges combined with considerable hydrodynamic loads (high swells and strong currents), the amount of erosion along the coastline can be distinctly greater.

In coastal lowlands, climate-change related greater precipitation can lead to more frequent flooding. Winter precipitation consists predominantly of rain while in summer there is a greater risk of heavy-rain events. As a means of preventing damage, and in particular for the sake of maintaining the continuity of agricultural production in the lowlands, there is an increasing requirement for artificial drainage by means of pumping stations in coastal areas. More frequent flood scenarios require higher performance from pumping stations, thus resulting in rising electricity consumption (cf. Indicator KM-I-6).

Based on the findings of the 2021 Climate Impact and Risk Analysis the highest risks in respect of sea temperatures and ice cover are expected to occur – with major certainty – with regard to the action field ‘Coastal and marine protection’. High climate risks also exist in respect of seawater quality and groundwater salination, height of sea level, changes to natural features along coastlines and overload conditions in drainage systems in areas at risk of flooding. The certainty of estimating such climate change impacts is between medium and high.

In addition, a high risk of damage to, or destruction of, coastal settlements and infrastructures is expected to set in by the end of this century. The probability of hydrodynamic climate change impacts such as increased water levels in connection with storm surges or changes in the current and tidal dynamics is estimated as medium. The same applies to the consequential increase in loads on, or the failure of, coastal protection structures. Nevertheless, the risk assessment for such climate change impacts is subject to low certainty.

The coastal and marine areas associated with the North Sea and Baltic Sea differ in terms of their morphological and hydrodynamic properties. Steep and shallow sections alternate along the coastline, and they react differently to the impacts of climate change. Furthermore, the North Sea is influenced by strong tides, whereas the tidal activity in the Baltic Sea is much less pronounced. For the purpose of monitoring, this requires that the indicators be developed and interpreted in a differentiated way for North Sea and Baltic Sea respectively. At the same time, the nationwide design of DAS Monitoring imposes restrictions on making statements regarding state-specific or even region-specific statements. This made it necessary for the 2023 Monitoring Report to work with case studies, in order to address important themes such as coastal erosion or the increasing challenges involved in the drainage of coastal lowlands (cf. Indicators KM-I-4 and KM-I-6). Case studies, of course, do not allow drawing any generic inferences regarding German coastal regions overall. For example, the case study on changes in the cliffscape on Fischland/Baltic Sea does not permit any statements on the coastal erosion experienced along other types of coastlines. Likewise, it would be out of the question to make any direct comparisons between the drainage conditions prevailing in the area covered by the case study carried out by the Eider-Treene-Schöpfwerksverband (Pumping Station Association) – illustrated in the indicator KM-I-6 – and other pumping station associations. As far as these themes are concerned, it is important not just to explore additional data sources, but also to develop advanced conceptual ideas of how to arrive at generalising statements that take into account any prevailing heterogeneous conditions.

Likewise, there are substantial methodical, partly also data-technical, challenges regarding the description of phenomena such as the displacement of the brackish-water zone within estuarine areas or even far inland, the salination of coastal groundwater resources or even the impacts of storm surges on flood protection in inland areas. The subgroup entitled Klimaindikatoren (climate Indicators), launched by LAWA for the purpose of developing joint indicators relating to water issues, has discussed these and other themes. Nevertheless, there are further scientific debates required in order to facilitate the development of meaningful indicators. A particular problem is that especially the coastal areas, including the estuaries of watercourses, are in several parts of their course strongly influenced by anthropogenic activities, thus producing a multi-layered complex of influences. Given this background, it is to some extent simply not possible to tease out the direct effects of climate change.

Given that in Germany, investments in coastal protection are financed predominantly from GAK funding, these investments can be illustrated in the nationwide GAK Reporting system (cf. Indicator KM-R-2). However, damage caused to coastal protection systems is not covered by a central database. The situation is similar with regard to any damage to settlements and infrastructures in the hinterland. It is not possible either to assess insurance data specifically for these regions. It is conceivable, however, that the ongoing work by BMUV and UBA in setting up a nationwide climate-damage register will produce further insights.

Potential negative effects on the coasts, resulting from utilisation for tourism purposes, are covered under themes in the DAS action fields entitled ‘Tourism industry’ (cf. Indicators TOU-I-1 and TOU-I-3) as well as ‘Human health’ (cf. Indicator GE-I-7). However, so far it has not been possible to carry out a comprehensive and systematic consideration process. This is true also, and particularly, with regard to adaptation measures and activities. In this respect, too, there are – in addition to data gaps – conceptual challenges that remain to be dealt with.

Generally speaking, the links between marine protection and the adaptation to climate change have been illustrated only marginally in DAS Monitoring, while marine ecosystems have to date hardly been focused on. As before, there are still knowledge and data gaps regarding these themes whilst there is genuine concern that climate change is fast becoming the predominant driver of the extinction of marine species. There is need for an in-depth discussion on potential indicators for themes such as acidification and the loss of oxygen (also the increase in death zones without oxygen) and associated impacts on species composition.

Effective adaptation to climate change is indispensable with regard to coastal protection. As a result of climate change, the existing technical and protective facilities have to withstand increased hydrological loads. At the same time the intensity of utilisation and the damage potential in coastal regions continue to increase. The dimensioning of coastal protection structures is therefore subject to regular inspection and adaptation of input parameters. An example of comprehensive consideration of the increasing danger from heightened storm surge water levels is the adaptation of land protection dykes in Schleswig-
Holstein (cf. Indicator KM-R-2). With a view to the expected rise in sea levels, unsafe dykes have been reinforced since 2001 with a safety margin of 0.5 metres. It is possible to offset a sea level rise of up to 1.0 metre by broadening the dyke crest and constructing a more gradual outer slope; this mode of construction has been implemented in dyke reinforcements since 2009. In 2018 the concept entitled ‘Klimadeich’ (climate dyke) was introduced, and incorporated in the general coastal protection plan (GKP) in 2022. This plan envisions increasíng the height of land protection dykes by means of several construction phases, with the purpose of offsetting a sea level rise by up to 2.0 metres. Recently, the proportion of land protection dykes without a safety deficit increased to 81.7 %.

The implementation of coastal protection measures is costly. The protective measures cover stabilising, extending or increasing the height of structures, but also the building of new protective structures, and increasingly, beach nourishment. Their purpose is to prevent the increasing coastal erosion and to offset the erosion of beaches. In Germany technical measures for coastal protection are financed predominantly by the GAK (cf. Indicator KM-R-2). For the purpose of adjusting to climate change, the Federal government has granted an additional 25 million Euros to the coastal Länder – via an GAK special framework plan covering the period of 2009 to 2025 – for coastal protection measures. The funding for the modified special framework plan covering the period of 2023 to 2026 has been increased substantially with effect from 2023. Furthermore, the funding from Federal government sources for measures to be taken in the run-up to 2040 has been secured already.

The national strategy for an Integrated Coastal Zone Management (IKZM) – relevant to the development of Germany’s coastal zones – was adopted by Federal government in 2006. Its objective is to develop and maintain the country’s coastal areas as ecologically intact and economically flourishing habitats. This constitutes an informal approach to coordination, participation and the exchange of experience. Although climate change is considered in the IKZM process, the process does not incorporate a specific adaptation strategy.

As far as marine protection is concerned, there have been no DAS Monitoring Indicators developed so far. It remains difficult to state any concrete adaptation measures. Ultimately, the issue must be to achieve a distinct reduction in pressure from anthropogenic utilisation, to provide more protective periods or to designate protective zones.

As far as research is concerned, core research objectives for marine, coastal and polar research were defined within the Federal government’s framework of the research strategy ‘Research for Sustainability’ (FONA); this definition is embedded in the inter-departmental specialised programme entitled MARE:N. MARE:N consists of the three pillars of coastal, marine and polar research and is conceived as an action framework for future funding measures. The MARE:N concept papers entitled ‘Küste im Wandel’ (coasts undergoing change) and ‘Blauer Ozean’ (blue ocean) (2018) as well as ‘Polarregionen im Wandel’ (polar regions undergoing change) (2021) paved the way for future research funding by the Federal Ministry of Education and Research (BMBF) in respect of coastal, marine and polar research. There are extensive research activities in progress under the two first-named programmes with focus on climate and coastal dynamics, ecosystem-related coastal protection and changes in biodiversity and material flows.