But the scientists noted that climate change alone didn’t create a catastrophe that killed thousands of people.
The massive amount of rainfall overwhelmed two dams, and the study said lives could have been saved had political turmoil not prevented stronger warnings, evacuation orders or other preparations for new weather extremes. The exact death toll is still unknown and estimates conflict, but over 3,000 bodies have been recovered and thousands of people are still missing according to the United Nations.
“This devastating disaster shows how climate-change-fueled extreme weather events are combining with human factors to create even bigger impacts, as more people, assets and infrastructure are exposed and vulnerable to flood risks,” Julie Arrighi, director of the Red Cross Red Crescent Climate Centre, said in a statement.
The study is the latest conducted through a global research partnership, known as the World Weather Attribution project, devoted to understanding climate change’s influences on extreme weather events, including storms, heat waves, cold spells and droughts. Similar studies have found such fingerprints on floods in Nigeria and Pakistan, while another concluded that climate change did not influence a food crisis in Madagascar.
The researchers also found a relationship between climate change and floods that Storm Daniel brought to Greece, Turkey and Bulgaria before it reached Libya, though the connection was not quite as strong. They estimated that in those areas, global warming increased the odds of such intense rainfall by tenfold.
Their analysis involves using climate data and weather model simulations to compare the current climate to that of the late 1800s, when the planet was about 1.2 degrees Celsius (2.2 degrees Fahrenheit) cooler, on average.
Flavio Lehner, an assistant professor at Cornell University who was not involved in the study, said those findings track with a well-established understanding that global warming can increase precipitation potential — and that the effect is most dramatic at the extremes, which can rise by 8 percent with each degree of warming.
“The more extreme the precipitation, the bigger of a relative effect we see from climate change,” Lehner said.
The rainfall over Libya was more intense because it was the product of what is known as a Medicane, or a tropical cyclone-like storm that forms over the Mediterranean. The sea, like vast swaths of the world’s oceans this summer, is significantly warmer than normal for this time of year. Warmer water is more prone to evaporation, and warmer air can hold more moisture.
Friederike Otto, one of the study’s authors, noted that in the months leading up to the floods, the Mediterranean was “a hotspot of climate change-fueled hazards.” In Greece, wildfires stoked by extreme heat were burning even as Storm Daniel bore down on the country.
In Libya, climate change has meant a decline in average annual rainfall, stressing a need to store as much water as possible. But the researchers said that meant a lack of consideration about what could happen if an extreme storm such as Storm Daniel came along.
Meanwhile, years of war and political rivalry have allowed Libya’s state services and infrastructure to wither, leaving the country unprepared to handle a humanitarian crisis.
“Ongoing conflict and state fragility in Libya compounded the effects of the flooding, contributing to a lack of maintenance and deterioration of dam infrastructure over time and increasing people’s risk,” the study authors wrote. “The conflict also limits nation-wide adaptation planning and coordination across a range of climate issues facing the country, such as water scarcity, and extreme weather including heat and floods.”
The Al-Bilad and Abu Mansour dams that failed upstream of Derna were built in the 1970s based on relatively short rainfall records, “and may not have been designed to withstand a 1 in 600 year rainfall event” like Storm Daniel, the researchers said.
They said the disaster in Libya stresses the importance of preparing for the weather extremes of the future, and not the past.
Otto, a senior lecturer in climate science at Imperial College London, said “there is absolutely no doubt that reducing vulnerability and increasing resilience to all types of extreme weather is paramount for saving lives in the future.”
