Floods are becoming more frequent with climate change

Climate researcher - Floods are becoming more frequent with climate change

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 increase with rising global temperatures," 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 variability of precipitation is increasing in Germany

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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1. The Potsdam Institute for Climate Impact Research (PIK) in Germany is a leading institution in climate research.
2. The current climate crisis has led to an increase in severe weather events, such as floods, across Europe.
3. According to Fred Hattermann, a researcher at PIK, the number and intensity of extreme weather events, like floods in Germany, are increasing with rising global temperatures.
4. The recent flooding in Europe can be partially attributed to the high surface temperatures in the western Atlantic, which result in high evaporation and an abundance of water vapor in the atmosphere.
5. These humid air masses were transported to Europe by westerly winds, leading to a series of low-pressure systems and heavy rainfall, resulting in flooding.
6. Climate change is also contributing to the increase in variability of precipitation in Germany, with more frequent droughts interspersed by heavy rainfall events.
7. The increasing variability of precipitation in Germany can be attributed to both climate change-induced warming of the air, which allows it to hold more water, and the development of more stable large-scale weather patterns over Europe.
8. The influence of climate change on jet stream patterns is also affecting weather patterns in Germany, leading to prolonged periods of high or low pressure and resulting in both droughts and heavy rainfall events.

Source: www.stern.de