By Stephanie Odiase
Heavy rainfall, which caused devastation in large parts of the Mediterranean in early September, was made more likely to happen by climate change resulting from greenhouse gas emissions, according to rapid analysis by an international team of climate scientists from the World Weather Attribution (WWA) group.
The study also found that the destruction caused by the heavy rain was much greater due to factors that included construction in flood-prone areas, deforestation, and the consequences of the conflict in Libya.
In early September, a cut-off low which affected Spain and a low-pressure system named Storm Daniel, which formed in the Eastern Mediterranean, brought large amounts of rain over a 10-day period to several countries, including Spain, Greece, Bulgaria, Türkiye and Libya. The heavy rain led to massive floods across the region, killing four people in Bulgaria, five in Spain, seven in Türkiye, and 17 in Greece, the study noted.
However, the greatest disaster occurred in Libya, where the floods caused the collapse of two dams. While the exact number of casualties is still not clear. There are currently 3,958 confirmed deaths in Derna alone and 170 people elsewhere in Libya, with over 10,000 people still missing.
To quantify the effect of climate change on the heavy rain in the region, scientists analysed climate data and computer model simulations to compare the climate as it is today, after about 1.2°C of global warming since the late 1800s, with the climate of the past, following peer-reviewed methods.
The scientists divided their analysis in three regions: Libya, where the analysis focused on the northeast part of the country, where most of the rainfall fell; Greece, Bulgaria and Türkiye, where the analysis looked at maximum rainfall over four consecutive days; and Spain, where most of the rain fell in just a few hours.
For Libya, the scientists found that human-caused climate change made the event up to 50 times more likely to happen, with up to 50% more rain during the period, as a result of human-caused greenhouse gas emissions. The event is still extremely unusual, and can only be expected to occur around once in 300-600 years, in the current climate, the study disclosed further
For Greece, Bulgaria and Türkiye, the analysis showed that climate change made the heavy rain up to 10 times more likely to happen, with up to 40% more rain, as a result of human activities that have warmed the planet.
“For this large region, which encompasses parts of the three countries, the event is now reasonably common, and can be expected about once every 10 years, meaning it has a 10% chance of happening each year. For central Greece, where most of the impacts took place, the event is less probable and only expected to happen once every 80-100 years, equivalent to a 1-1.25% chance of happening each year”, the study showed.
Meanwhile, in Spain, where most of the rain fell in just a few hours, the scientists estimated that such heavy rainfall is expected once every 40 years, but could not conduct a full attribution analysis as the available climate models poorly represent heavy rainfall on timescales shorter than a day.
A key finding of the study is that the very large impacts observed in some of the regions were caused by a combination of high vulnerability of the population and their exposure to the event. In the affected area in Central Greece, most of the cities and communities and a large part of the infrastructure are located in flood-prone areas.
Similarly, in Libya, a combination of several factors including long-lasting armed conflict, political instability, potential design flaws and poor maintenance of dams all contributed to the disaster. The interaction of these factors, and the very heavy rain that was worsened by climate change, created the extreme destruction, the study, conducted by 13 researchers as part of the World Weather Attribution group, concluded.