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Destroyed neighborhood in Derna, Libya, days after the rains

Photo: STR / EPA

Climate change has recently left its mark: human-induced warming has increased the likelihood of heavy rainfall up to ten times in Greece and up to 50 times in Libya. This is shown by a quick analysis of the "World Weather Attribution".

On September 10, storm "Daniel" caused severe flooding in eastern Libya. In the vicinity of the particularly hard-hit city, two dams broke, entire neighborhoods of the city were washed into the sea. Thousands have lost their lives, thousands are missing, exact figures are still missing. The sobering number of researchers for the country: climate change made floods up to 50 times more likely, and they were also accompanied by up to 50 percent more rain during this period. Under the current climatic conditions, the event is likely to occur only about once in 300–600 years.

The sometimes catastrophic extent was therefore favored by construction work in flood-prone areas, by the consequences of the civil war - and the deforestation of forests. The disasters make it clear that infrastructure must also be prepared for the future climate, in Libya, for example, for the long-term decline in average precipitation and at the same time the increase in extreme heavy rainfall events.

However, the researchers provide drastic figures not only for Libya, but also for Greece, Bulgaria and Turkey, where floods had also caused devastation. According to the study, the events became up to ten times more likely due to global warming and came with up to 40 percent more rain. In central Greece, where most of the effects have been recorded, such a weather event can be expected every 80-100 years.

Summer in Greece was marked by fires and heat waves. When »Daniel« moved across the country, it was still burning in places, »which overwhelmed the resources and possibilities for response«. Deforestation and a relatively high level of urbanization have also changed the landscape – and increased the number of people who were now affected by the floods.

In order to find out what quantitative role climate change played in the heavy rainfall events, the scientists used climate data and simulations and compared them with historical data.

However, the researchers also point to uncertainties, as the events would have taken place on relatively small areas – making them difficult for climate models to capture. It cannot be completely ruled out that climate change did not influence the probability and intensity of the events. But, the authors write, there are several reasons "why we can be confident that climate change has made events more likely." These include, for example, studies that show an increase in heavy rainfall due to global warming.

"As with any study on the attribution of events, it comes down to the overall picture, which undoubtedly points to a moderate role of human-induced climate change in exacerbating the event," Karsten Haustein of the University of Leipzig told the Science Media Center. "The research follows the established WWAs principles for rapid attribution, which are based on peer-reviewed methods and data that meet the highest quality standards."