Studies show: After the flood is before the flood
Rain, rain, rain: The situation in the flood areas is critical. And even when the floodwaters have subsided, Germany must prepare for the next floods. Because, as many studies show, these will occur more frequently in the future. Just like another extreme weather event.
According to researchers, floods and droughts will continue to increase. "Many studies, including our own, show that the number and intensity of extreme events such as floods in Germany will increase as global temperatures rise," says Fred Hattermann from the Potsdam Institute for Climate Impact Research (PIK), Hydroclimatic Risks working group.
One reason for the current flooding is probably the high surface temperatures of the western Atlantic for the time of year, which lead to high evaporation and thus a lot of water vapor in the atmosphere, explains Hattermann. These humid air masses were transported to Europe by the prevailing westerly winds in our latitudes, where a chain of low-pressure systems moving quickly across Central Europe resulted in very heavy rainfall in the fall and winter and then flooding. "The soils were saturated with water and then hardly absorb any more water."
The long-term average of precipitation in Germany has hardly changed. "There are no strong trends for Germany, but the variability of precipitation is increasing," says Hattermann. In short: there is more rain, but also longer dry periods.
According to Hattermann, there are two reasons for this. Firstly, climate change is warming the air, which can then absorb more water. "The amount of water per cubic meter of air has increased." This initially means longer dry spells - and when it does rain, more water falls on the ground.
Secondly: "We have more stable large-scale weather patterns over Europe." This is linked to the influence of climate change on the jet stream, an air current over the north polar region, although the individual relationships have not yet been precisely clarified. Such a situation has led, for example, to the long-lasting high-pressure weather conditions such as in 2018 or in spring 2023.
"An area of high pressure rotates clockwise and brings dry air from the Eurasian region to Germany," says Hattermann. "In 2021, we had an area of low pressure where the wind turned anticlockwise and brought moist air from the Mediterranean region to Germany." This led to the masses of water in the Ahr Valley in 2021.
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- In the wake of the devastating floods in Germany, officials are urging preparation for future floods, as numerous studies from institutions like the Potsdam Institute for Climate Impact Research (PIK) suggest that floods and droughts will become more frequent and intense as global temperatures rise.
- Björn Alexander, a researcher from PIK's Hydroclimatic Risks working group, highlights that one factor responsible for the current flooding may be the high surface temperatures in the western Atlantic, leading to increased evaporation and high water vapor content in the atmosphere, which was then transported to Europe by the prevailing westerly winds.
- As Germany grapples with the aftermath of the floods, experts warn that climate change is leading to more unpredictable weather patterns, such as longer dry spells followed by heavier rainfall, a situation that played a role in the recent flooding in Lower Saxony, a state in Germany.
Source: www.ntv.de
