At least eleven people died in California due to three major fires that forced the evacuation of over 250,000 people. The balance of victims could increase because many people are still missing. The biggest fire – and the only one that has so far been mortal – is what affects the northern part of the state and that in little more than 24 hours has devastated 28,000 hectares and has devoured much of the municipality of Paradiso, Di 26,000 inhabitants, about 280 kilometers from San Francisco, with 6,700 houses affected. In Los Angeles there are two other fires, one of which started Thursday on the coast and forced to evacuate the entire population of Malibu, known for being the residence of many Hollywood stars: this fire had burned up to 28,000 hectares yesterday and he continued out of control. What happens in California so that the fires are so catastrophic? There are four key factors.
The climate of California, with dry summers, has always caused fires, but with climate change the problem has worsened. "We have temperatures between 3.6 and 5.4 degrees warmer than normal without global warming," says Park Williams, a bioclimatologist at Columbia University. The registration of fires in California dates back to 1932: the ten main fires since then, nine have occurred since 2000, five since 2010 and two in the same year.
Even if the conditions are favorable to fires, there is still someone or something that originates. Sometimes the spark is of the same nature as a thunderbolt, but more often the origin is human. The dead fires in Sonoma County began with the fall of the electric towers. The sparks of the wheel of a truck that had exploded were the cause of Carr's fire this year. Furthermore, people decide to live in areas closer and closer to the forest, which increases the risk.
It is paradoxical, but the extinction of fires in the past has also worsened the current situation. "During the last century we fought the fire, and we did it very well in the western United States," says Dr. Williams. "And every time we fought a fire successfully it meant, in the end, that many things were not burned in. So, in the last hundred years we have had an accumulation of vegetation in many places." In recent years, the United States Forest Service He tried to remedy the situation with the fires under control.
The winds of Santa Ana
Every fall, the strong gusts known as the Santa Ana winds bring dry air from the West Bank to the south of California, adds Fengpeng Sun, a professor at the University of Missouri-Kansas City. He was the coauthor of a 2015 study that suggested that California had two distinct fire seasons. What goes from June to September, driven by a combination of warmer and drier climate, with fires that tend to be more inland, in the forests of higher altitude; and another that goes from October to April, and is driven by the winds of Santa Ana. These fires tend to spread three times faster and burn more close to urban areas, and have been responsible for 80% of economic losses since the 90s. Santa Ana winds not only dry the vegetation, but also wash the fires and spread the fire. If the autumn rains, which usually start in October, do not arrive in time, as the year has passed, the wind increases the drought.