At least 228 people lost their lives in severe floods that pummelled swaths of Germany and Belgium last month
Climate change made the deadly floods that devastated parts of Germany and Belgium last month up to nine times more likely, according to an international study published on Tuesday.
At least 190 people lost their lives in severe floods that pummelled western Germany in mid-July, and at least 38 people perished after extreme rainfall in Belgium's southern Wallonia region.
Using the growing speciality of attribution science, climate experts are increasingly able to link manmade climate change to specific extreme weather events.
To calculate the role of climate change on the rainfall that led to the floods, scientists analysed weather records and computer simulations to compare the climate today -- which is around 1.2°C warmer due to manmade emissions -- with the climate of the past.
They focused on one- and two-day rainfall levels, and found that two particularly hard hit areas saw unprecedented precipitation last month.
In the Ahr and Erft regions of Germany, 93 millimetres of rain fell in a single day at the height of the crisis. The Belgium region of Meuse saw a record-breaking 106 mm of rain over a two-day period.
They calculated that the floods were between 1.2 and nine times more likely to happen in today's warmed climate, compared to a scenario where no heating had occurred since the pre-industrial era.
Such downpours over Germany and the Benelux region are now between 3-19% heavier because of human-induced warming, according to the study, organized by World Weather Attribution.
"Climate change increased the likelihood (of the floods), but climate change also increased the intensity," said Frank Kreienkamp, from the German weather service.
Friederike Otto, associate director of the University of Oxford's Environmental Change Institute, said that the floods showed that "even developed countries are not safe from severe impacts of extreme weather that we have seen and known to get worse with climate change."
By analysing local rainfall patterns across Western Europe, the authors of the study were able to estimate the likelihood of an event similar to last month's floods occurring again.
They found that similar events could be expected to hit any given area about once in 400 years at current warming levels.
This means several events on the scale of the German and Belgian floods are likely across Western Europe within that timeframe, they said.
The scientists said that they focused on rainfall in this study as river level data was missing after several measurement stations were washed away in the floods.