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How does climate change make fires worse?

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.”

Good weather for a fire
A firefighter can tell the recipe for “promotional fire”: hot, dry and windy.
It is no surprise that many of the tropical and temperate regions destroyed by an increase in forest fires are those predicted in climate models to see higher temperatures and more drought.
“In addition to increasing dry and hot air, climate change &#821

1; by increasing evaporation and the presence of drought – also creates more flammable ecosystems,” notes Christopher Williams, environmental science director at Clark University, Massachusetts.
In the last 20 years, California and southern Europe have seen several droughts of a magnitude that used to occur once in the century.

More fuel
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.”

Changing the landscape
To make matters worse, new species grow better suited to semi-dried conditions.
“Plants that have disappeared as moisture, replaced by more fla mmable plants that withstand dry conditions, such as rosemary, wild lavender and thyme,” says Vennetier.
“Increasing mercury and less rain sends water-laden trees and bushes root deeper into the soil and sucks each drop of water as they can to nourish leaves and leaves. needles.
This means that the moisture in the soil that may have helped to brake a fire sweeping through a forest or branch is no longer there.

Longer Season
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.

More flash
“The hotter it gets the more flash you have,” says Mike Flannigan, Professor at Alberta University, Canada and director of the Western Partnership for Wildland Fire Science.
“Especially in the northern areas, it means more fires”.
At the same time, he noted that 95 percent of wildlife around the world is started by humans.

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.”

Reinforced intensity
Climate change does not increase probability
“If the fire becomes too intensive” as in California right now and in Greece last summer – “There is no direct action you can take to stop it,” says Flannigan.
“It’s like spying on a campfire.”

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.

Positive Feedback
Globally, forests hold about 45 percent of the earth’s locked coal and quit a quarter of people’s greenhouse gas emissions.
But when forests die and burn, some of the coal is released back into the atmosphere and contributes to climate change in a bad loop, as researchers call positive feedback.

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