Thursday , September 29 2022

How does climate change make wild fires worse?


Dying wild fires, such as those that have been defeated in north and south California, have become more common in the US state and elsewhere in the world in recent years. AFP talked to scientists about the ways in which climate change can make them worse.

Other factors have also led to an increase in the number of large fires, including human frequency on wooded areas, and the management of suspicious forests. "The patient was already ill," in the words of David Bowman, a professor of environmental change biology at Tasmania University and wild wildlife expert.

"But climate change is the accelerator."

Severe weather for fire

Any firefighter can tell you the recipe for "auxiliary fire weather": hot, dry and windy.

It is not surprising, therefore, that many tropical and terminal regions are damaged by surge in forest fires that are predicted in climate models to see higher temperatures and more drought.

There are heavy smoke devices in the forest where Firewood burns heavy near Paradise, California, on November 11, 2018.

There are heavy smoke devices in the forest where Firewood burns heavy near Paradise, California, on November 11, 2018.


"As well as bringing more dry and heavy air, climate change – by raising evaporation rates and the prevalence of drought – also creates more flammable ecosystems," said Christopher Williams, director of environmental sciences at the University of Clark in Massachusetts.

In the past 20 years, California and southern Europe have seen many drought of the size that occurred only once a century.

More fuel

Dry weather means more trees, shrubs and dead grass – and more fuel for the fire.

"All of these extremely dry years create a great deal of biomass after disasters," said Michel Vennetier, engineer at the National Research and Science of Science and Technology for the Environment and Agriculture (IRSTEA).

"That's a fierce ideal."

Change scenes

In order to make things worse, new species that are better adapted to barrage conditions grow in place.

"Plants that like moisture have disappeared, replacing more flammable plants that can resist dry conditions, such as rosemary, wild lavender," said Vennetier.

"The change takes place quite quickly."

Thirsty plants

With the increase in mercury and less rainfall, trees and shrubs under pressure send roots deeper into the soil, sucking every drop of water that they can eat to leaves and needles.

That means that the moisture in the ground that could have helped to slow down a fire sweep a forest or garriga no longer there.

Longer term

In the temperate atmosphere of the north hemisphere, the fire season was historically short – July and August, in most places.

"Today, the period that is susceptible to wild fires has extended from June to October," said IRSTEA scientist, Thomas Curt, referring to the Mediterranean basin.

In California, which has emerged from a recent drought of five years, some experts say that there is no longer any term – fires can occur during the year.

Small lightning

"The warmer you get, the lightning you have," said Mike Flannigan, a professor at the University of Alberta, Canada and director of the Western Wildland Fire Science Partnership.

The wild fires spread across California have claimed up to now nine lives and forced tens of thousands to flee.

The wild fires spread across California have claimed up to now nine lives and forced tens of thousands to flee.


"Especially in the northern areas, which corresponds to more fires."

At the same time, he noted that 95 per cent of wild fires worldwide were started by people.

Nant jet has weakened

Normal weather patterns for North America and Eurosia depend on the high-high, high-air airflows generated by the contrast between polar and comic temperatures – known as jet numbers.

But global warming has arisen temperatures in the Arctic twice as fast as the global average, weakening that current.

"We see more extreme weather due to what we call blockbacks, which is a high pressure system where sinking air is warmer and drier along the way," said the Flannic .

"Firefighters have known for decades that these are favorable to fire activity."

Unstable control

Climate change not only increases the likelihood of wild fires, but their intensity as well.

"If the fire is too intense" as in California at present, and Greece last summer – "there is no direct measure that you can take to stop," said the Flannic.

"It's like throwing on a campsite."

Beetle fittings

With increasing temperatures, beetles have moved to the north to the Canadian morning forests, causing damage – and killing trees – along the way.

"Bark beet peak raids increase forest flammability temporarily by increasing the amount of dead material, such as needles," said Williams.

Positive feedback

Globally, forests hold about 45 per cent of Earth's carbon after landfill and heat a quarter of human greenhouse gas emissions.

But as forests die and burn, some of the carbon is released back to the atmosphere, contributing to climate change in a vicious link scientists call "positive feedback."

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