The world’s largest producers of fossil fuels are responsible for more than a third of the areas burned by forest fires in western North America over the past 40 years, according to a study published Thursday in the scientific journal Environmental Research Letters.
The fires ravaging the western United States and southwestern Canada have been worsening for several decades, the study’s lead author, Kristina Dahl, of the Union of Concerned Scientists, told AFP. They spread with more intensity, destroy larger areas, reach higher altitudes and last for several seasons.
So far, the public has borne the cost of rebuilding and protecting against the new normal that fire hazard has become, “so we wanted to better understand the role played by big business emissions in the fossil fuels” in this evolution, she continued.
“We wanted to highlight their role so that they assume their share of responsibility in the cost” of the fires and their repercussions, added Kristina Dahl.
The researchers combined observed data and climate models to determine the extent to which emissions of carbon dioxide (CO2) and methane (CH4) of the 88 largest fossil fuel producers, such as ExxonMobil, BP, Chevron and Shell, had contributed to atmospheric drought.
Plant warming and drying
They concluded that these emissions were responsible for an average rise in global temperatures since the beginning of the 20e century of 0.5°C, half of the observed warming.
This rise in temperature worsened the water vapor pressure deficit in the western United States atmosphere by 11%.
A high water vapor pressure deficit means that the ambient air absorbs more of the water droplets emitted by plants and soils during photosynthesis, which dries them out and makes vegetation more vulnerable to fires.
Recent research shows that as the water vapor deficit increases, the areas ravaged by fires expand.
According to the Union of Concerned Scientists study, the destruction of 8 million hectares by forest fires in the western United States and southwestern Canada — the size of the Czech Republic — is thus due to the largest producers of fossil fuels and cement.
This represents 37% of the area totally destroyed by wildfires in western North America between 1986 and 2021.
The year 1986 was chosen as the reference point because it was from that year that the data on the area burned by forest fires became reliable.
Among other factors responsible for the multiplication and worsening of the fires, the study notes the abandonment of the ancestral practice of regulating forests by deliberate but limited fires, which has resulted in thicker and more dense undergrowth. likely to catch fire.
Urbanization in wooded areas is also a factor cited by the researchers, as it increases the risk of accidental fire starting.