It has never rained so much in Colombia. "Over the past 10 months we have registered five or six times more rainfall than usual," says weather specialist Ricardo Lozano. Torrential rain and flooding have affected more than three-quarters of the country. The most recent Red Cross bulletin reports 425 fatalities and 3 million disaster victims.

With 12,000 homes destroyed and 356,000 damaged, thousands of people have had to move out, taking refuge in temporary shelters. More than 1m hectares of land are underwater. "But the disaster prevention system worked," Lozano adds, saving between 5,000 and 10,000 lives.

Colombia is known for its heavy rain and apparent lack of seasons, but this year the downpour has been almost continuous. The mountains are sodden, so runoff flows down the slopes to fill rivers, which flood the plains and coastal areas. Mudslides have damaged the precarious road system. At 2,500 metres above sea level even the vast Sabana plain, on which the capital Bogotá is built, is partly flooded. Food prices are going up and the drainage system is completely saturated, with the risk of a dengue epidemic.

This is mainly the fault of La Niña, a cyclical weather system. "It used to occur once every five to six years, but it is increasingly frequent and severe due to global warming," says Lozano. The current spell of bad weather is expected to last another two months.

The authorities are also culprits. "They have allowed corrupt politicians, cattle breeders, mining companies, logging firms, drug traffickers and property developers to destroy woods and wetlands, and wreck river basins," says the economist Roberto Arango. "They have tolerated rampant social inequality, so the poorest people must live in hazardous areas."

This story originally appeared in Le Monde