BERLIN (AP) — Scientists say that global warming makes the kind of extreme rainfall that caused deadly flash flooding in western Europe last month more likely, though it remains unclear exactly how much.
At least 220 people died in Germany and Belgium on July 14-15 when swollen streams turned into raging rivers, sweeping away houses, roads and bridges, and causing billions of euros (dollars) in damage.
A study released Tuesday by the World Weather Attribution group used historical records and computer simulations to examine how temperatures affected rainfall from the late 19th century to the present. While the study hasn’t been assessed by independent scientists yet, its authors use widely accepted methods to conduct rapid assessments of specific weather events such as floods, droughts and heat waves.
It found that across a large strip of western Europe — stretching from the Netherlands to Switzerland — the amount of rainfall in a single day increased by 3% to 19% over the period, during which global temperatures increased by 1.2 degrees Celsius (2.2 degrees Fahrenheit).
Experts say that for every 1 degree Celsius (1.8 F) the planet warms, the air can absorb 7% more water. When that water is released, it causes more extreme rainfall.
The study, conducted by almost 40 researchers from six European countries and the United States, calculated that downpours of the kind that caused last month’s floods are now 1.2 to 9 times more likely — and this will increase further if the planet continues to heat up.