Every year, forest fires sweep the US state of California, causing dozens of deaths, but what secret makes this western state vulnerable to fires every year?
In the latest forest fire disaster, California forest fires have so far killed at least 25 people, officials said.
According to The New York Times, there are four main reasons for California's "burning" year after year:
Climate change
The first reason is climate in California, they are like many areas in the western United States, suffer from vegetation damage in the summer, due to lack of rainfall and high temperatures.
With global climate change due to environmental pollution and carbon dioxide emissions, temperatures are rising annually, drying out already dry vegetation, making it vulnerable to drought-prone fires.
Humans
Even if the conditions are appropriate for the outbreak of the fire, there must be something or a person to trigger the first spark, and in most cases, the beginning is a "human error".
"California has a lot of people and a dry and long season," said environmental scientist Park Williams. "Humans always make fire sparks in fires."
In California, the proportion of people who decide to live in areas close to forests is rising, and new residential areas near the forests have been built after cities are saturated, increasing the proportion of forest fires caused by humans.
American History
The history of the United States "suppressed" forest fires in the last century, caused by the generation of "surplus" fires in the present era.
"Over the last century, we have fought the fire, and we have had great success across the western United States, which means that a range of things that could have burned did not burn," Dr. Williams said.
In recent years, the United States Forestry Commission has attempted to correct past practices through "deliberate" fires that are deliberately fabricated and controlled.
The winds of Santa Ana
A strong storm known as Santa Ana winds brings dry air from the Great Basin area of the west to southern California, said Vingping Sun, a professor at the Department of Earth Sciences at the University of Missouri-Kansas City.
Sun made a study confirming that California has two distinct seasons. The first runs from June to September, and is led by a combination of warmer and drier weather, is the season of western fires, and tends to be internal, in high forests.
The second fire season runs from October to April and is driven by the winds of Santa Ana. These fires spread three times faster than usual, attacking residential areas, accounting for 80 per cent of economic losses over two decades.
