Study shows the correlation between wildfires and the climate crisis

First, US climate scientists determined the extent to which greenhouse gases from the world’s largest fossil fuel companies contribute to wildfires.

Their analysis, published Tuesday in the Environmental Research Lettersfound that carbon dioxide and methane emissions from the so-called “Big 88” were responsible for more than a third of the area burned by wildfires in western North America over the past 40 years.

Wildfires in the western US and southwestern Canada have been worsening for decades: they burn more intensely, over longer seasons, cover larger areas and reach higher altitudes, senior author Christina Dahl of the Union of Concerned Scientists (UCS) told AFP.

So far, the cost of rebuilding and increasing resilience is largely borne by the general public, “so we wanted to better understand the role the fossil fuel industry’s emissions have played in changing the wildfire landscape,” she says.

“We really wanted to highlight their role in this, so they can be held responsible for their fair share of the cost.”

Thirst in the atmosphere

Using climate modeling, the team determined that emissions from the Big 88 — which includes ExxonMobil, BP, Chevron and Shell — were responsible for increasing average global temperatures by 0.9 degrees Fahrenheit (0.5 degrees Celsius) since the start of the 20th century, or roughly half the warming. notable.

For the purposes of this study, the authors included all emissions across a fossil fuel’s life cycle—from extraction and combustion to refining and in-vehicle use, for example.

The companies’ contribution to planet-wide warming was then used to calculate how much they added to the increase in the “vapor pressure deficit,” or VPD—a measure of the air’s ability to draw water from plants and soil—within western North America.

Since warmer air can hold more water vapor, rising temperatures caused by climate change are also causing this much thirstier atmosphere.

Higher VPD makes the region more vulnerable to fires, and recent research has demonstrated a clear exponential relationship between increases in this aridity index and area burned due to wildfires.

Integrating all of these elements, Dahl’s research team found that emissions from the Big 88 were responsible for 37 percent of the total area destroyed by wildfires in the western United States and southwestern Canada between 1986, when reliable fire area data became available, and 2021.

That’s 19.8 million acres (8 million hectares) – an area roughly the size of the Czech Republic.

The study also found that emissions from the same companies were responsible for nearly half of the observed increase in VPD since 1901.

Other factors that have increased fire hazard conditions over the past century include aggressive fire suppression that has resulted in a large buildup of vegetation that would normally have been burned in smaller, regularly occurring fires, often run by indigenous communities.

Accidental ignitions also increased as humans moved into fire-prone areas.

A growing field of research

The research builds on a backlog of climate “attribution” studies, which have calculated how much greenhouse gas emissions from burning fossil fuels have contributed to global temperature rise, sea level rise, and ocean acidification.

Such work, Dahl said, paved the way for affected communities to seek redress through lawsuits, and helps shift the conversation about addressing climate change away from individual responsibility.

“Reducing our individual carbon footprints is a narrative that has been pushed very hard by the fossil fuel industry,” she said.

“While individuals need to make the best possible choices, we also need to acknowledge that we live in a reality shaped by these corporations and that our choices have been constrained by them.”

UCS is pushing government investigations into past and ongoing disinformation campaigns by industry with the goal of denying climate science predicted by internal corporate modeling.

© 2023 AFP