Effects chain – Example ‘coastal and marine protection’ | Umweltbundesamt

Climate changes relevant to the action field

State: Air and seawater warming

Some of the ways in which climate change makes itself felt are – rising air temperatures and a changing precipitation regime. With an increase by 1.7 °C between 1881 and 2022, the temperature rise in Germany was 0.6 °C greater than the global mean (cf. Fig. 1) including the marine regions which are not subject to fast warming. As air temperature rises, sea temperature rises too. Approximately 90 % of the additional heat quantity induced by climate change is absorbed by the oceans. As a result, the oceans cumulatively become a ‘reservoir’ of gigantic quantities of heat.

Impacts of climate change

Impact: KM-I-2 Sea levels

The warming of oceans leads to an increase in the volume of seawater. Apart from the melting of glaciers and polar ice shields, this expansion of the seas is considered a crucial cause of global sea level rise. The sea levels on North Sea and Baltic Sea coasts are rising too. In this context, the rates of increase (adjusted for land uplift and land subsidence respectively) for the 20th century are between 1.4 and 2.1 mm annually thus equating to the same scale as the increase in global sea levels. According to the current progress report (AR6) issued by the Intergovernmental Panel on Climate Change (IPCC), the scenario entitled ‘Der fossile Weg’ (The fossil pathway, SSP5-8.5) predicts a probable increase of sea levels by 0.63 to 1.01 metres by the end of this century. The ice-shield processes – so far inadequately understood – in the Antarctic might contribute an additional metre to the increase in sea levels.

Impact: KM-I-3 Height of storm surges

For coastal regions, in particular estuaries and coastal lowlands, rising sea levels signify an increasing risk of exposure to storm surges and inundations. At the moment, trends are not indicating the imminence of more frequent or more intensive storm surges. However, it is inevitable that the higher baseline values in terms of sea level rise will result in higher absolute water levels at times of storm surges. In addition, the hazard potential is augmented by the increasing utilisation pressure on coastal areas.

Adaptations – activities and results

Response: KM-R-2 Land protection dykes without safety deficit

In order to protect infrastructures, buildings and human life in endangered coastal regions, the coastal Länder implement coastal protection measures. In Schleswig-Holstein land protection dykes protect the adjacent coastal lowlands from inundation for a total length of 433 kilometres. To make dykes strong enough to withstand future loads, unsafe dykes (that fall short of valid protection standards), are reinforced in line with the concept entitled ‘Klimadeich’ in order to be able to withstand 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 %.