For the first time, US climate scientists have quantified the extent to which greenhouse gases from the world’s top fossil fuel companies have contributed to wildfires.
Their study found that carbon dioxide and methane emissions from the so-called “Big 88” firms were responsible for more than a third of the area burned by forest fires in western North America over the past 40 years. These fires are burning more intensely, over longer seasons, covering larger areas and reaching higher elevations.
Up to now, the cost of rebuilding and increasing resilience has largely been footed by the general public, “so we wanted to better understand the role that fossil fuel industry emissions have had in altering the wildfire landscape,” said author Kristina Dahl.
“We really wanted to put a spotlight on their role in that, so that they can be held accountable for their fair share of the cost.”
With the use of climate modeling, the team was able to determine that emissions from the Big 88-which includes ExxonMobil, Chevron and Shell-were responsible for increasing global average temperatures by 0.5 degrees Celsius since the start of the 20th century, or roughly half of the observed warming.
In this study, the authors included all emissions across the life cycle of fossil fuels-from extraction and flaring operations to refinement and use inside a vehicle.
The companies’ contribution to global warming was then used to calculate how much they added to a rise in “vapor pressure deficit” or VPD-a measure of air’s ability to draw water out of plants and soils-within the western North America region.
Since warmer air can hold more water vapor, rising temperatures caused by climate change are causing this measure of atmospheric thirst to increase too.
A higher VPD makes an area more prone to fire, and recent research has shown a clear exponential relationship between increases in the aridity indicator and the area burned by forest fires.
The research team found that emissions from the Big 88 were responsible for 37 percent of the total area destroyed by forest fires in western United States and southwestern Canada between 1986 and 2021.
https://phys.org/news/2023-05-quantifies-link-climate-crisis-wildfires.html