Libya's deadly flash flood in September constituted a climate and environmental catastrophe that requires $1.8 billion in reconstruction and recovery, an international report said on Wednesday. Huge swathes of the city of Derna were destroyed in the flood, after heavy rainfall from Storm Daniel crashed through two aging dams, sweeping entire districts into the Mediterranean. Population growth and development downstream, limited weather forecasting in the region and inadequate early warning systems to ensure evacuation accentuated the disaster, the report said. Climate change had made the rainfall unleashed by Storm Daniel up to 50 times more likely and 50 percent more intense, according to the report. Despite calls by the UN for Libya's ruling factions to put aside their differences to formulate a coordinated response to the Derna disaster, there has been little sign they are willing to do so.