Facts: This is how the analysis has been done
World Weather Attribution is an international research network that analyzes the possible impact of climate change on extreme weather events.
To quantify the effect of climate change on the heavy rain, climate data and climate model simulations were analyzed to compare today’s global warming of around 1.2 degrees with past conditions.
The researchers divided the study into three geographical areas:
Libya, with a focus on the northeast, where most of the precipitation fell.
Greece, Bulgaria and Turkey, where the analysis looked at the maximum rainfall over four consecutive days.
Spain where most of the rain fell in just a few hours.
The analysis has been done in a short time and has not been reviewed by other researchers. But the methods used are scientifically recognized, according to the authors who, however, point out that there were mathematical uncertainties because climate models are not so good at precipitation in smaller areas.
The researchers therefore cannot completely rule out that climate change has not affected the probability of the downpours, but highlight several aspects that make them “convinced” that it has played a role, including that increased temperatures generally lead to heavier precipitation and that data from measuring stations in the area shows a trend of more intense rains.
Terrible scenes unfolded in Darnah as extreme downpours caused two dams on the outskirts of the Libyan city to burst. River waves rushed through the streets, buildings were washed into the sea, and entire families perished in an instant.
Storm Daniel, which formed in the eastern Mediterranean at the beginning of September, brought large amounts of rain over ten days to several countries, including Spain, Greece, Bulgaria, Turkey and Libya.
It led to massive flooding and deaths have been reported from Bulgaria, Spain, Turkey and Greece – and from Libya where around 4,000 people have been confirmed dead and many are still missing.
Climate change made the heavy downpour in northeastern Libya up to 50 times more likely, with 50 percent more rain during the period, according to a rapid analysis by the research network World Weather Attribution. But the event is still extremely rare and in the current climate can be expected once every 300-600 years.
In Greece, Bulgaria and Turkey, climate change has made heavy rain up to ten times more likely, with up to 40 percent more rain. That type of precipitation can be expected in the area as a whole approximately every ten years, according to the researchers.
But in central Greece, which was hit hard by the floods, that type of rain is considered less likely and is expected to occur once in 80-100 years.
Satellite images show the devastation in the village of Palamas in central Greece after the floods earlier in September.Cascading effects
The researchers also point out that devastating effects in certain parts of the investigated area can be linked to weaknesses in the ability to deal with the advance of the storm. In Greece, the worst affected cities and communities are located in flood-prone areas. And in Libya, long-term conflict, political instability, construction deficiencies and poor dam maintenance contributed to the magnitude of the disaster.
“Climate change made the rain more intense,” says Friederike Otto, climate scientist at Imperial College of London and one of the authors of the study, at a press conference.
— But the combination of disasters, such as Greece’s forest fires and Libya’s long-term conflict, has played a role in terms of vulnerability and people’s exposure.