Germany’s vulnerability to climate change: heavy rain in focus

Extreme weather events will continue to increase in Germany. How vulnerable we are depends on a variety of factors, and vulnerability assessments help to explore these factors. Urban areas, for example, are especially affected by heavy rainfall. In new research, adelphi research examines the current state of heavy rain preparedness in Germany and formulates recommendations for adaptation strategies – strategies relevant to individual citizens as well as the public and private sectors.

The effects of climate change are already noticeable in Germany. Last year, for example, was the hottest and driest year since records began in 1881. In the late spring of 2018, a number of severe thunderstorms, often combined with hail and torrential rain, affected the south and west of Germany. Extreme weather events of this kind are continuing to appear this year as well. As climate change progresses, we must continually update our understanding of Germany’s vulnerability in order to develop effective adaptation strategies.

The dimensions of vulnerability

How vulnerable we are depends on a variety of factors. These are often divided into three aspects:

• The impact of changing climatic parameters like precipitation or temperature on a region or state (‘climatic influence’ and ‘spatial exposure’);
• How sensitive a region or state is to such changes (‘sensitivity’); and
• The potential of a region or state to counteract the negative impact or take advantage of potential positive effects (‘adaptive capacity’).

Vulnerability assessments enable the systematic analysis of these factors and the development of effective adaptation strategies. In this way, our municipalities, cities, states and companies can plan for a sustainable future.

adelphi research – expert in vulnerability assessments in Germany

The German Strategy for Adaptation to Climate Change, adopted by the federal government in 2008, calls for the assessment of German vulnerability every five to seven years. adelphi research published one vulnerability assessment on behalf of the Federal Environment Agency back in 2015, and has been commissioned to lead the Climate Impact and Vulnerability Assessment for the years 2018 to 2021, which was published in June 2021. In addition, adelphi research developed a guideline for climate impact and vulnerability assessments aimed at federal and state authorities. The guideline is, among other things, a collection of existing conceptual and methodological approaches to enable independent assessments at the regional and national level.

Currently in focus: Heavy rain and its impact in Germany

Now adelphi research has applied this expertise to the study of Germany’s vulnerability to heavy rain. ‘Heavy’ rainfall refers to exceptionally high levels of precipitation in a short period of time. The consequences of extreme rain include floods, infrastructure damage, sewer overflow, soil erosion and landslides. Against this background, the report ‘Precautions for heavy rain events and measures for water-sensitive urban development’ and a discussion paper on climate-resistant urban development assess the current state of heavy rain preparedness in Germany and develop recommendations for adaptation strategies.

eavy rain is difficult to predict and causes extensive damage

Heavy rainfall has already caused a great deal of property damage. According to the German Insurance Association, total damages from storms with heavy rains increased tenfold in 2016 compared to the previous year. Danger zones are not geographically restricted to river or coastal regions. Urban areas in particular are affected by the high degree of sealing, concentrated infrastructure and elevated population density. At the same time, heavy rainfall events are difficult to predict and often small in geographical scale – summer thunderstorms, for example. Moreover, it is hard to anticipate where heavy rainfall events will occur, as past downpours are not an indicator.

Future requirements for heavy rain preparedness

In light of all this, vulnerability assessments for specific sites and the communication of risks related to heavy rainful are especially important. Heavy rain risk maps, which depict areas that could be affected by flooding, are considered a vital tool in this context. While some municipalities have created their own maps, a lack of uniform guidelines and minimum standards remains. Such standards and recommendations would improve risk management, as maps could be made available to citizens and stakeholders from diverse disciplines – civil engineering, for example, or public administrations related to water management or green space planning.
Risk maps could serve another important purpose, for example raising awareness about heavy rain among citizens. The population’s capacity for self-help and self-provision are among the most important identified adaptation measures when it comes to heavy rain. However, there is still a lack of suitable strategies for the broad communication of Germany’s vulnerability in this regard – information that would stimulate critical self-provision.

Reduce Germany’s vulnerability by increasing adaptive capacities

adelphi research’s reports demonstrate that it is possible to influence Germany’s vulnerability to extreme weather events like heavy rain. In addition to climate-resistant urban development, heavy rain risk management is decisive here, and the standardisation of heavy rain risk maps must play as central a role as the communication strategies aimed at awareness and self-provision. This could increase Germany’s adaptive capacity and reduce its vulnerability.