Climate change

Climate change is rapidly becoming one of the most significant risks for World Heritage sites (IUCN). The Wadden Sea World Heritage Property is already affected directly (e.g., by an increase in temperature and sea level rise) and by secondary effects (e.g., by an import of southern warm-water species and changes in the timing of life cycle events). Climate change and enhanced sea level rise may seriously impact the structure, functions, and characteristic biodiversity of the Wadden Sea ecosystem, as well as the safety of the inhabitants of the region. Addressing these impacts as a cross-cutting theme is a main challenge for the Trilateral Wadden Sea Cooperation (TWSC), in particular with given uncertainties in the prediction of climate change effects.

Trilateral activities, addressing the intricate challenges of climate change, date back to 1998, with the establishment of the trilateral Working Group Coastal Protection and Sea Level Rise (CPSL). Comprising experts in coastal and nature protection, as well as spatial planning, this group has played an essential role in providing insights to the Trilateral Governmental Conferences. Building on this foundation, the year 2011 witnessed a significant development of these efforts, with the establishment of the trilateral Task Group Climate (TG-C), since 2019 Expert Group Climate Change Adaptation (EG-C), advancing the responsibilities of its predecessor, the CPSL. This transition underscores a continuous commitment to staying at the forefront of climate-related concerns and adapting strategies to the evolving dynamics of the Wadden Sea region.


Climate Change Adaption Strategy

The trilateral work related to climate change currently focuses on enhancing the resilience of the Wadden Sea ecosystem to the impacts of climate change. TG-C developed a trilateral Climate Change Adaptation Strategy (CCAS) with seven strategic objectives and guiding principles. Adopted at the 12th Wadden Sea Conference 2014 in Tønder, Denmark, the strategy aims to enhance the resilience of the Wadden Sea ecosystem.

Seven CCAS strategic objectives and guiding principles

Natural dynamics

The Wadden Sea ecosystem has adapted to environmental changes for millennia. Allowing and restoring natural dynamics increases the resilience of the Wadden Sea to climate change.


Interconnectivity of habitats allows species and communities to follow shifts of climatic conditions; thereby preventing extinction and securing adaptation of characteristic biodiversity.


Climate change is a cross-cutting theme and requires an integrated approach across borders and disciplines.


To cope with uncertainties of predictions, a flexible approach is required. Adaptive management facilitates timely responses to new information on actual and projected changes.

Long-term approach

Climate change and accelerated sea level rise are gradual processes that need a long-term management approach.

Site specific approach

Challenges and optimal adaptation may differ throughout the Wadden Sea Region, hence cooperation and knowledge exchange on best site-specific solutions are required.


Active involvement of a wide range of stakeholders should lead to awareness for the challenges of climate change and acceptance of adaptation measures.


The strategy’s implementation was evaluated in a CCAS monitoring report in 2017. The seven principles are being applied in a wide range of projects and policies in the trilateral Wadden Sea Area. TG-C recommended that monitoring of the trilateral CCAS be continued and the results embedded in long-term trilateral climate change policies and, furthermore, that trilateral knowledge exchange on best practices for adapting to climate change be stimulated. The current EG-C is supporting these recommendations and is working towards implementation.


Climate Vulnerability Index

The Wadden Sea is a World Heritage site because of its exceptional natural significance, its Outstanding Universal Value (OUV). As such, the permanent protection of this Heritage is of utmost importance to the whole international community. In 2020-2022, the Wadden Sea trialed the Climate Vulnerability Index (CVI) methodology. The CVI is a systematic tool to rapidly assess the risk of climate change to World Heritage.

The three key climate stressors impacting the Wadden Sea OUV identified with this methodology are:

  • Temperature trend (air and/or water);
  • Extreme temperature events; and
  • Sea level rise.

These were consistent across the two timeframes considered (ca. 2050 and ca. 2100) using a ‘business-as-usual’ climate scenario (RCP8.5), which represents the most likely consequence of current international policies linked to greenhouse gas emissions. OUV Vulnerability was assessed as High (the highest category) for both timeframes. Whilst the vulnerability associated with the two temperature-related climate stressors was assessed as High in both timeframes, the vulnerability to impacts from sea level rise escalated from Low in ca. 2050 to High in ca. 2100. Collectively and for both timeframes, there is potential for major loss or substantial alteration of the majority of the attributes that convey the OUV.


Coastal Flood Defense and protection and Nature-based Solutions

Climate change effects in the Wadden Sea are strongly interlinked with coastal protection, and spatial planning, as flooding and coastal erosion due to sea level rise and storm surges pose significant risks of loss of life and damage to the economy in the Wadden Sea area. About 3.5 million inhabitants live in the Wadden Sea region and are dependent on effective and reliable coastal risk management (CPSL, 2010). Management plans and projects must cope with uncertainties regarding the extent of climate change and responses of the highly complex Wadden Sea system. Coastal Flood Defense and protection is also a key topic in the SIMP Integrated Management Plan for ONE Wadden Sea World Heritage.

Traditionally, hard infrastructures such as concrete dams or dikes covered with stone are being used to protect against flooding. With increasing effects of climate change, coastal areas will be increasingly vulnerable to flooding, erosion, biodiversity loss, and higher cost of this grey infrastructure.  The demand for adaptive flood protection and combined coastal risk and nature conservation management is increasing and with it new concepts of eco-engineering are emerging. Nature based Solutions (NbS) is such an emerging complementary concept, in which natural processes are used to protect against coastal erosion and flooding. Both nature and people may benefit from these solutions.

A common transnational evidence base to optimise the effectiveness of NbS was developed in the INTERREG North Sea Region project “Building with Nature” (BwN; 2015-2021). In this North Sea region-wide project, partners from Belgium, Denmark, Germany, the Netherlands, Norway, Scotland, and Sweden worked together with the overall objective of making coasts, estuaries, and catchments more adaptable and resilient to the effects of climate change. The Common Wadden Sea Secretariat (CWSS) was partner in BwN and supported  the evidence base for best practices for Building with Nature activities with a Wadden Sea Climate Change Adaptation Information Platform. This includes trilateral policy and management, best practices, monitoring and assessment, and activities in communication and education (Policy reports, scientific reports, projects etc.) until 2018.

From 2022-2028, a follow-up North Sea Region Interreg Project MAinstreaming NAture-BAsed Solutions through COASTal systems (MANABAS COAST) is setting the stage for widescale application and implementation (mainstreaming) of Nature-based Solutions (NbS) in coastal systems of the North Sea Region while combining Flood and Coastal Erosion Risk Management and Biodiversity goals. Pilot examples reach from Sweden to France and include several cases in the Wadden Sea. As project partner, CWSS is facilitating knowledge exchange with the Trilateral Wadden Sea Cooperation and trilateral Working Groups.