The flooding that has hit southern Germany over recent days can be attributed to a low pressure zone over the northern Mediterranean, experts at the Munich Re reinsurer said on Monday.
Damage caused by cyclones known as Genoa lows or Vb cyclones are on the rise, according to data collected by the reinsurer, the world's largest.
"They suck up water over the Mediterranean Sea and then move from northern Italy in the direction of the Balkans," Munich Re head climatologist Ernst Rauch said.
"Then the exceptional nature of these Vb weather conditions is revealed. The extremely moist cloud vortex turns away to the north, comes back and is squeezed against the Alps," Rauch said. "We then experience this pressing out of the clouds over a period of several days."
The difference between this phenomenon and flash flooding as occurred further north in Germany along the Ahr Valley in 2021 is the extent over a wide area and the duration of the rainfall over several days.
These Vb weather conditions occur only in spring and summer, according to Rauch. Data from the German Meteorological Service (DWD) show that the number of Vb events has increased over recent years. Record falls have also been recorded in certain areas.
"Record precipitation is probably linked to climate change, as warmer air can hold more moisture – per degree around 6% or 7% more moisture," the climatologist said. A link to climate change was plausible, even if scientific proof was not possible, he added.
"Our data show that damage from severe weather is rising, and this statistic makes a link with climate change likely," Rauch said. He called for action to find a response to increasing damage and extreme events. "The central answer is prevention," he said.
