The heavy rainfall that caused deadly flooding across Germany, the Netherlands, and Belgium in July was made more likely by the climate crisis. The floods in Europe, which killed at least 220 people as towns were swamped, were up to nine times more likely because of global warming, a group of researchers found.
In July, heavy rainfall led to severe flooding particularly in the German states North Rhine-Westphalia and Rhineland-Palatinate, as well as in Luxembourg, and along the river Meuse and some of its tributaries in Belgium and the Netherlands. The flooding resulted in 184 deaths in Germany and 38 in Belgium, as well as infrastructure damage.
Scientists from the World Weather Attribution (WVA) group compared the frequency of the rainfall seen in Europe in today’s heated climate with the frequency expected in a world with no human-caused climate change. They used meteorological measurements, high-resolution computer models, and peer-reviewed research methods.
"We combined the knowledge of specialists from several fields of study to understand the influence of climate change on the terrible flooding last month, and to make clear what we can and cannot analyze in this event," Sjoukje Philip, a climate researcher at the Royal Dutch Meteorological Institute and part of the WWA team, told BBC.
A climate crisis
While it’s difficult to assess the climate influence on heavy rainfall at local levels, the researchers could show that increasing greenhouse gas emissions have made events like the one seen in Europe more likely. In the current climate, for any location in Western Europe, a rainfall event like the one just seen is expected once every 400 years.
The researchers found that climate change made the extreme rainfall in Europe between 1.2 and nine times more likely to happen and that such downpours in the region are now 3% to 19% more intense. The hotter air resulting from global warming can hold up to 7% more water vapor for every 1ºC rise, according to the study’s findings.
The researchers focused on two areas that were particularly affected by the rainfall: the German districts near the Ahr and Erft rivers, where 93 millimeters of rain fell in a day, and the Belgian Meuse region, where 106 millimeters fell over two days. River levels couldn’t be analyzed mainly because measurement stations were destroyed by the floods.
“These floods have shown us that even developed countries are not safe from the severe impacts of extreme weather that we have seen and that are known to get worse with climate change,” Friederike Otto from Oxford University told BBC. “This is an urgent global challenge and we need to step up to it. The science is clear.”
In a previous study, the same group of researchers had previously found that the heatwave seen in July in North America would have been “virtually impossible” without climate change. Before the industrial era, this type of heatwave just wouldn’t have happened. Even in today’s warming world, the heat was a once-in-a-millennium event.
The heatwaves and the floods reinforce the findings of the recent landmark report by the Intergovernmental Panel on Climate Change (IPCC), which said there’s “unequivocal” evidence that emissions from human activities are the main cause of global warming. Still, the report said the worst consequences can be avoided by ambitious climate action.
The full study can be accessed here.