Overnight floods have wreaked havoc in parts of Western Europe, claiming dozens of lives. Scientists say climate change has played a role.
On Thursday, 46 people were reported dead and dozens missing in Germany, Belgium, Switzerland and the Netherlands. Storms and overnight rains caused rivers and reservoirs to overflow, and flash floods turned roads into raging torrents that swept cars and destroyed buildings.
In recent weeks, Germany has experienced a rollercoaster ride of high, dry temperatures followed by widespread rainfall.
This was interrupted on Wednesday and Thursday by catastrophic flooding in several parts of western Germany and neighboring countries. Experts say such extreme weather events have occurred once in a generation but are likely to become more frequent – and more intense – in the future, suggesting that climate change is having an impact on our lives.
Is this normal weather for Germany?
“Normally, we only see weather like this in winter,” said Bernd Mehlig, environmental officer for the state of North Rhine-Westphalia (NRW) in western Germany, “where the region is most affected by precipitation.” Something like this, in this intensity, is completely unusual in summer.
In an interview with WDR on Thursday, a spokeswoman for Hagen’s crisis management team predicted that water levels would reach levels that occur four times in a century, with parts of the city reportedly inaccessible and isolated because of the high water levels.
“This is the new normal,” says Johannes Quaas, a meteorologist at Leipzig University.” Climate change is also changing the definition of normal weather. We are gradually approaching a new normal that includes different rainfall patterns.
Is climate change making floods worse?
Rising temperatures make extreme weather events more intense. When air warms, it contains more moisture, a phenomenon scientists discovered as early as the 19th century. A one degree Celsius rise in temperature increases the air’s ability to hold moisture by 7%. Rising global temperatures also lead to faster evaporation of water on land and in the sea, which in turn leads to more extreme precipitation and more storms.
“The rainfall we have seen across Europe in recent days has been extreme and its intensity has been exacerbated by climate change and will continue to intensify with further warming,” says Friederike Otto of the Environmental Change Institute at Oxford University.
When factors such as soils and drainage systems cannot absorb water quickly enough, or urban development prevents the drainage of rainfall, surface runoff can become flash floods that can cause significant damage.
Predicting extreme weather events is not difficult, but it remains almost impossible to accurately predict where a storm will dump huge amounts of rain and which areas will be most affected, says Quas, adding that this makes it difficult for communities to prepare for disasters and mitigate damage.
In addition, many natural floodplains have disappeared as changes in temperature and weather patterns have led to the destruction of some vegetation and other land barriers.