DWD: Climate change made flooding more likely

Southern Germany - DWD: Climate change made flooding more likely

The likelihood of such heavy rainfalls as in late May and early June in South Germany is, according to an analysis, already significantly increased in the context of the climate crisis. Instead of occurring roughly every 42 years on average, such rainfalls are now estimated to occur approximately every 30 years in the region, the Regional Climate Office Potsdam of the German Weather Service (DWD) reported.

In a globally two-degree warmer future, comparable events in the region are expected to occur on average every 23 to 25 years. However, the computational uncertainties regarding these figures are quite large.

Heavy rainfalls between May 30 and June 3 led to landslides and floods in South Germany. In Bavaria and Baden-Württemberg, local record rainfall amounts were measured, particularly affected were the drainage areas of the Danube and Neckar, according to the DWD.

Looking back for comparison

The scientists of the meteorological service focused on the drainage areas of the rivers Neckar and Danube, where the strongest rainfalls were measured in their so-called attribution study. The analysis showed that the climate change had increased the likelihood of such or even stronger rainfall events by a factor of approximately 1.4 (uncertainty range of 0.8 to 4.4). Such an event could therefore occur more frequently than in a 1.2-degree cooler climate, as it was around the year 1900. The calculations also suggest that the intensity of such a rainfall event in this region has probably increased by about four percent. "Such an event brings about four millimeters (liters per square meter) more rainfall than in a 1.2-degree cooler climate," it was stated.

Water absorbs more easily in warm air

Rising temperatures could theoretically lead to an intensification of rainfalls, as explained in the study. The water-absorbing capacity of the air for water vapor increases with rising temperature. "This increased water-absorbing capacity, combined with stronger evaporation over warmer sea surface temperatures, leads to more moisture being taken up in the air over the sea." When these air masses then pass over the continents, they could potentially release more water. "The potential for heavy rainfalls therefore increases fundamentally due to climate change."

For an attribution study, meteorological data from the past decades and climate simulations are statistically evaluated. At the beginning of the month, the research consortium Climameter had already presented a similar analysis on the events in South Germany. According to their findings, the rain that caused the floods was up to 10 percent stronger than without human-induced warming.

Even seemingly small amounts of intensified rainfall can have disproportionately large effects, as the consortium explained. For example, the Ahrtal flood of 2021 was intensified by 3 to 19 percent due to climate change.

1. The DWD's Future Climate Scenarios indicate that extreme rainfall events like the one in South Germany might become the new normal in a 2-degree warmer future, occurring approximately every 23 to 25 years.
2. In light of the climate crisis, the likelihood of experiencing such heavy precipitation along the Neckar river, as observed in the past, is projected to occur more frequently, approximating every 30 years.
3. The German government, recognizing the increased probability of floods due to climate change, is investing in flood protection measures in Southern Germany, specifically in areas like Stuttgart and Baden-Württemberg.
4. According to the DWD, the future of the Danube river, which experienced significant flooding due to the heavy rainfall, is under threat due to climate change, as extreme weather events become more common.
5. In an attempt to understand the role of climate change in the heavy rainfalls, scientists at Potsdam's Regional Climate Office are studying the drainage areas of rivers like the Neckar and Danube, using frameworks like Attribution Analysis.
6. A climate scientist in Munich warned that Germany, as a whole, is becoming increasingly vulnerable to extreme weather events, as temperatures rise and precipitation patterns change, exacerbating the climate crisis.
7. Bavaria has taken measures to decrease its carbon footprint, aiming to become climate neutral by 2050, in response to the increasing probability of floods and other extreme weather events related to climate change.
8. In the context of the climate crisis, scientists and policymakers are urging countries to take aggressive action to reduce greenhouse gas emissions and mitigate the impacts of the climate crisis, including extreme weather events like the storm in South Germany.
9. As the effects of climate change become more noticeable, Germany, including its southern regions like Baden-Württemberg and Bavaria, needs to be prepared for an increased frequency and intensity of extreme weather events, such as heavy rainfall and flooding.
10. In the face of the climate crisis, the WMO report on global warming and extreme weather events highlights the need for international cooperation and collective action to avoid the worst-case scenarios, including the risk of severe flooding in regions like the Neckar and Danube valleys.

Read also:

• Tough return to normality in snow and ice
• Steinmeier joined a moment of silence - a legal battle over an AfD protest.
• German national soccer team on their way to participate in the European Championship qualifying matches.
• The flooding has lessened, but the aftermath of mud remains.