Ten ways climate change can make wildfires much worse
DEADLY wildfires such as those raging in northern and southern California have become more common across the state and elsewhere in the world in recent years. AFP talked to scientists about the ways in which climate change can make them much worse.
Other factors have also fuelled an increase in the frequency and intensity of major fires, including human encroachment on wooded areas, and questionable forest management. “The patient was already sick,” in the words of David Bowman, a professor of environmental change biology at the University of Tasmania and a wildfire expert.
“But climate change is the accelerant.”
Any firefighter can tell you the recipe for “conducive fire weather”: hot, dry and windy.
No surprise, then, that many of the tropical and temperate regions devastated by a surge in forest fires are those predicted in climate models to see higher temperatures and more droughts.
“Besides bringing more dry and hot air, climate change — by elevating evaporation rates and drought prevalence — also creates more flammable ecosystems,” noted Christopher Williams, director of environmental sciences at Clark University in Massachusetts.
In the last 20 years, California and southern Europe have seen several droughts of a magnitude that used to occur only once a century.
Dry weather means more dead trees, shrubs and grass — and more fuel for the fire.
“All those extremely dry years create an enormous amount of desiccated biomass,” said Michel Vennetier, an engineer at France’s National Research
Besides bringing more dry and hot air, climate change — by elevating evaporation rates and drought prevalence — also creates more flammable ecosystems. Christopher Williams, director of environmental sciences at Clark University in Massachusetts
of Science and Technology for Environment and Agriculture ( IRSTEA). “That’s an ideal combustible.” To make matters worse, new species better adapted to semiarid conditions grow in their place.
“Plants that like humidity have disappeared, replaced by more flammable plants that can withstand dry conditions, like rosemary, wild lavender and thyme,” said Vennetier.
“The change happens quite quickly.”
With rising mercury and less rain, water- stressed trees and shrubs send roots deeper into the soil, sucking up every drop of water they can to nourish leaves and needles.
That means the moisture in the earth that might have helped to slow a fire sweeping through a forest or garrigue is no longer there.
In the northern hemisphere’s temperate zone, the fire season was historically short — July and August, in most places.
“Today, the period susceptible to wildfires has extended from June to October,” said IRSTEA scientist Thomas Curt, referring to the Mediterranean basin.
In California, which only recently emerged from a fiveyear drought, some experts say there’s no longer a season at all — fires can happen year-round.
“The warmer it gets, the more lightning you have,” said Mike Flannigan, a professor at the University of Alberta, Canada and director of the Western Partnership for Wildland Fire Science.
“Especially in the northern areas, that translates into more fires.” — AFP