Deadly wild fires like those raging in northern and southern California have become more common in the United States and…
Deadly wild fires like those raging in northern and southern California have become more common in the United States and other world in recent years. AFP talked with researchers about how climate change could make them worse.
Other factors have also resulted in an increase in the frequency and intensity of major fires, including human forest counting and doubtful forest management. “The patient was already ill,” according to David Bowman, a professor of environmental change biology at the University of Tasmania and a fire brigade expert.
“But climate change is the accelerant.”
Dry weather means more dead trees, bushes and grass – and more fuel for
“All these extremely dry years create a huge amount of dried biomass,” says Michel Vennetier, engineer of France’s national research for Science and Technology for Environment and Agriculture (IRSTEA).
“It is an ideal combustible.”
In the northern hemisphere’s temperate zone, the season was historically short – July and August in most places
“Today, the period for receiving fires has increased from June to October,” said IRSTEA researcher Thomas Curt, with reference to the Mediterranean Basin.
In California, just recently emerging from a five-year drought, experts say that there is no season anymore – fires can happen all year long.
Weakened jet stream
Normal weather patterns across North America and Eurasia depend strongly on the powerful high-altitude air currents – produced by contrast between polar and equatorial temperatures – known as the jet current.
But global warming has increased the temperature of the Arctic twice as fast as the global average, which weakens these currents.
“We see more extreme weather because of what we call blocked ridges, which is a high pressure system in which air falls, gets hotter and drier under the way,” says Flannigan.
“Firemen have known for decades that these contribute to fire activity.”
With rising temperatures, beers have moved north to Canada’s boreal forests, causing chaos – and killing trees – along the way.
“Bark beetle outbreaks temporarily increase the ability of wood flame by increasing the amount of dead material, such as needles,” Williams said.