Extreme rainfall such as the floods in Limburg, Belgium and Germany this summer is now more common as a result of climate change. The amount of precipitation during this type of heavy rainfall has also increased by 3 to 19 percent due to the changing climate. This is evident from a international research, in which Dutch climate scientists have also contributed.
Parts of western Europe were hit by severe flooding from July 12-15, following heavy rains. In one day, for example, more than 90 millimeters of rain fell around the Ahr and Erft rivers in Germany, much more than previous records. It led to considerable damage in Limburg, at least 220 people were killed in Belgium and Germany.
During and after the floods, the question was often asked: is this due to climate change? And will we see this more often in the future?
Sjoukje Philip of the KNMI participated in the study: “We looked at the precipitation that led to these floods and see that it has indeed become more intense due to a changing climate and that this precipitation also occurs more often due to climate change.”
1.2 to 9 times more often
How much more often cannot be said exactly; there is a considerable margin of uncertainty. The researchers compared the current situation, in a world that has warmed on average 1.2 degrees, with the time before greenhouse gas emissions started, in the mid-19th century. “The likelihood of such an event occurring now has increased by a factor of between 1.2 and 9 in this region,” the report said.
A few factors came together in the July floods. The area was already soaked with water from previous showers and could therefore absorb less new rainwater. In addition, warmer air can hold more water vapor. Moreover, that air stayed in the same place for a very long time. All this resulted in very high rainfall in one region.
The researchers think that in the area between the Alps and the Netherlands, such a confluence of circumstances can occur once every 400 years. But that doesn’t mean, they emphasize, that it will now be hundreds of years before it happens again. That chance is the same every year.
Wake-upcall
Climate scientists are increasingly able to determine whether there is a link between incidental weather extremes and global warming. Previously, there were studies into the extreme hitte in Canada of this summer, and the bushfires in Australia last year. Although a clear link with climate change is not always found, this was the case in these two examples.
What does that mean and how much extra heat can we tolerate on Earth? NOS op 3 figured it out:
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