Wildfires, peat fires and controlled burns on farmlands kill 339,000 people worldwide each year, said a study released on Saturday that is the first to estimate a death toll for landscape fires.
Most of those deaths are concentrated in sub-Saharan Africa, where an estimated 157,000 people die as a result of being exposed to such fires annually, with southeast Asia ranking second with 110,000 deaths.
“I was surprised at our estimate being so high when you consider that the exposure to fire smoke is quite intermittent for most people,” said lead author Fay Johnston, of the University of Tasmania.
“Even in southeast Asia and Africa, [fire] is a seasonal phenomenon. It is not year round,” Johnston said at the American Association for the Advancement of Science annual meeting in Vancouver where she presented her research.
The study, which Johnston said was the first of its kind to attempt to estimate a death toll from wildfires and landscape burns, was published on Saturday in the journal Environmental Health Perspectives.
Researchers looked at the number of deaths from all causes in areas that were exposed to heavy smoke and landscape fires between 1997 and 2006.
They used satellite data and chemical transport models to assess the health impacts of particulate matter smaller than 2.5 micrometers, a major byproduct of landscape fire smoke.
The number of deaths from wildfires came in far below the previously estimated global tolls for indoor air pollution at 2 million people a year and urban air pollution at 800,000.
However, the study authors said their findings indicated that “fire emissions are an important contributor to global mortality.”
The research also suggested a significant link between climate and fire mortality.
About twice as many people died during El Nino years when the surface ocean temperature rises in the tropical eastern Pacific Ocean (averaging 532,000 deaths) as during cooler La Nina years (averaging 262,000 deaths).
Deaths could be reduced if people stopped burning tropical rainforests in order to harvest palm oil and other products, Johnston said.
However, fires will only get more severe in the future, according to Mike Flannigan, a professor at the University of Alberta and a government scientist with Natural Resources Canada, who has conducted research to model how severe fires will be by the years 2081 to 2090.
Using a variable he called “cumulative daily severity rating,” Flannigan’s projections show that fire activity is “increasing over most of the globe, particularly the northern hemisphere, by a factor of two to three.”
That means “significant increases” in fire activity should be expected by the end of this century as the globe gets warmer, he said.
“It is the extreme weather that drives fire activity and if we expect more extremes in the future, which we do, then it is only going to get worse,” Flannigan told reporters. “It is getting to the point where it is beyond our control.”
Already, between 350 million to 450 million hectares are burned every year in wildfires, covering an area about the size of India and costing billions of dollars to fight and contain.
“The risk to life and infrastructure is only going to increase under climate change because of a warming climate,” Flannigan said.
Firefighting methods such as aerial suppression may have to be abandoned because they will not work against hotter, more intense fires, he said.