Could climate change be causing floods?
Torrential downpours and severe flooding have put a stranglehold on the country's southern region, submerging homes, overflowing rivers, and breaking dikes and dams. At least four individuals have lost their lives as a result of these floods. This marks the fourth major flood incident in the past year. Hydrologist Bruno Merz provides insight into why such extreme weather events may occur and the role of climate change during an interview.
ntv.de: Mr. Merz, it seems Germany is experiencing one after another flood disaster. Are instances like these a direct result of climate change?
Bruno Merz: Every individual weather event cannot be definitively connected to climate change. Let's use the analogy of lung cancer in smokers: If a person smokes for 30 years and then develops lung cancer, it cannot be indisputably proven that the cancer resulted from smoking. However, the likelihood of developing lung cancer increases through smoking. It's similar with floods. Because climate change modifies the probability of severe weather events. Scientific evidence supports this occurrence.
Does that imply that heavy rain, floods, and flooding will become more frequent in the future?
There are several types of floods. Floods with a direct connection to climate change are caused by short and intense rain showers, often resulting from thunderstorms. With global warming, local intense rain showers increase in frequency.
How does this occur?
The warmer air can accommodate more water - on average, it holds seven percent more water for each degree of warming. This means there's more water in the atmosphere that can potentially rain down. Additionally, a study demonstrated that in the past several years, there have been about 30 percent more record-breaking rainfall events in comparison to a world without climate change.
But this recent flood in southern Germany seems more related to persistent rain rather than short, intensive rain showers. How does this link to climate change?
The initial conditions play a crucial role. We experienced a very warm and humid May this year, with the average temperature at 2.8 degrees above the 1961-1990 reference period. Additionally, it was the third wettest May on record. The numerous rainfall filled the soil so it could no longer absorb additional water. Another factor is the alteration of large-scale weather patterns.
What do you mean by large-scale weather patterns?
Large-scale weather patterns encompass the dynamics of the atmosphere, such as where highs and lows occur and how long they persist. They also describe the path of a low-pressure system, which brings rain, and how quickly it moves. It's been observed that these large-scale weather patterns now last longer. Low-pressure systems move more slowly, leading to heavy rainfall in one specific location.
What's the current situation along the Rhine and Danube rivers like?
Yes, the drawn-out duration of these major weather systems is one of the factors contributing to the magnitude of the flooding in southern Germany. A low-pressure system emerged from the Mediterranean, bringing moist air with it. This system has been stuck for a while, causing prolonged rainfall.
Have droughts become a thing of the past?
Sadly, no. Reviewing the rainfall record in Germany over the past couple of decades reveals that, on average, rainfall has increased. However, when it does rain, the occurrence is often more intense.
How well can these flood events be predicted?
Actually, quite well. The German Weather Service creates rainfall predictions, which are then applied by the state-run flood forecasting centers to predict water levels at gauges. This technology is more reliable for larger rivers and catchment areas.
Why are floods still so devastating, despite our efforts in flood protection?
Germany has already made significant investments in flood mitigation measures, such as retention basins and dikes. However, climate change plays a significant role in these extreme weather events. Our flood protection methods were not conceived to cope with these situations.
What are the necessary steps to improve flood protection?
We can't entirely halt all the damage. The goal is to prevent repetitions of major incidents like the Ahr Valley flood three years ago. Measures for nursing homes, maintaining critical infrastructure, and keeping the power grid from failing should be emphasized.
In conclusion
As Bruno Merz details, the frequency and intensity of floods can be directly related to climate change. While we have a reasonable understanding of how to predict and anticipate these weather events, we are not prepared for the more extreme cases that could occur. Focusing on improving and enhancing our flood protection systems is crucial in mitigating the disastrous consequences they bring.
Can you feel hopeful that we'll be able to control the detrimental effects of climate change enough to limit intense weather events in the future? Or is it possible that these situations are now the norm and we should accept that fact?
Personally, I'm quite disgruntled with how things have turned out. The Earth has already warmed by approximately 1.5 degrees in large part due to human activities. The negative repercussions of this change are palpable and will persist. I sincerely hope that society makes greater strides towards addressing climate change within the next 10 to 20 years. However, realistically, we need to brace ourselves for the reality that we'll experience more frequent floods, droughts, and similar calamities.
Read also:
- Despite efforts to improve flood protection, climate change has made extreme weather events, such as the recent floods in Baden-Württemberg and Bavaria, more frequent and severe.
- Hydrologist Bruno Merz, who conducted a study on record-breaking rainfall events in the past several years, noted a 30% increase in such events due to climate change.
- As a result of these increased rainfall events and the longer duration of major weather systems, Germany has seen an increase in frequent and intensive floods, like the one that affected the Rhine and Danube rivers.
