Carbon emissions can be attributed to nearly 40% of land burned by western wildfires.

Nearly 40% of the area of ​​forest burned by wildfires in the western United States and southwestern Canada in the past 40 years can be attributed to the carbon emissions associated with the world’s 88 largest fossil fuel producers and cement manufacturers, according to new research that seeks to retain oil. Gas companies are responsible for their role in climate change.

The results were published Tuesday in the journal Environmental Research LettersThe authors conclude that emissions from the extraction of fossil fuels, as well as the burning of those fuels, have increased the land area burned by wildfires by raising global temperatures and amplifying dry conditions across the West. This increasing aridity, or drought, the researchers say, has caused the atmosphere to become “thirstier” for water, draining moisture from trees and branches and making them more vulnerable to fires.

The study is the latest in a growing body of research known as extreme event attribution, or attribution science, that seeks to quantify the extent to which global warming contributes to events such as heat waves, droughts and wildfires.

“We hope that people in communities affected by wildfires will see this work and consider whether they want to hold these companies accountable,” said study author Christina Dahl, principal climate scientist at the Union of Concerned Scientists.

To estimate the fossil fuel industry’s impact on wildfires, Dahl and her colleagues drew on previous research that showed that carbon emissions traced to the 88 largest fossil fuel producers and cement manufacturers–including ExxonMobil, BP, Chevron and Shell–contributed significantly to average global warming. the earth. (Cement production is responsible for 8% of the carbon dioxide emitted by humans—much less than burning fossil fuels.)

The researchers found that changes in the global mean temperature are positively correlated with changes in the vapor pressure deficit in western North America, a measure of how effectively the air dries up the vegetation and vegetation that eventually becomes fuel for wildfires.

“I actually laughed because I had never had such a strong correlation in my data before,” she said.

The researchers were then able to estimate that emissions from major carbon producers contributed 48% of the increase in vapor pressure deficit observed over the past 120 years. Previous research has shown that this rise is closely related to the increase in burned forest lands in the western United States and southwestern Canada.

From there, the researchers found that emissions were responsible for 37% of the 53 million acres of forest — or 19.8 million acres — that wildfires have burned since 1986.

The findings do not take into account the effects of non-climatic factors, including fire suppression, indigenous burning bans, and increases in human-caused fires associated with more people moving into wilderness areas, which played a role in increasing the size and severity of individual fires. , but did not affect the relationship between climate and burned area.

Asked to comment on the results, a Western State Petroleum Assen spokesman said. He said that “demonization” of the fossil fuel industry will not bring solutions.

“We all want the same thing: affordable, reliable and cleaner energy and fuel,” Kevin Slagle wrote in an email. “A press release from a well-funded activist group with a long history of attacking the energy industries is unhelpful for the serious, realistic discussions of climate and energy policy needed to get us there.”

Until relatively recently, the general position of the climate science community was that no single extreme event could be attributed to global warming, said Noah Divenbaugh, a climate scientist at Stanford University’s Doerr School of Sustainability, who was not involved in the study. That changed in the early 2000s, he said, and attribution of extreme events has since become a strong subfield of climate science.

Although the subfield does not exist to provide data for legal procedures, in some ways it arose from matters of law, he said. Some of its first examinations of the scientific literature, he said, were in law review articles on the need to determine the contribution of historical global warming to individual events for purposes of assigning responsibility.

Since then, attribution research has served as the basis for liability lawsuits against fossil fuel companies.

Last month, in what was seen as a major victory for plaintiffs, the US Supreme Court refused to hear appeals from oil and gas companies that were seeking to bring climate change lawsuits by state and local governments to federal courts. The decision paved the way for dozens of similar lawsuits to be heard in state courts, where it is believed that communities that sue have better chances of winning big damages.

“What this study shows is that, using current peer-reviewed methods, it is possible to accurately track contributions from source emissions to impacts,” Divenbaugh said.

Another scientist who was not involved in the study said the authors’ methodology appeared sound.

Rong Fu, director of the Joint Institute for Regional Earth System Science and Engineering at UCLA, has also studied the link between global warming and increasingly destructive wildfires. If anything, Fu said, the study authors may have underestimated the effects of the companies’ emissions because they included aerosol emissions in their calculations.

She said aerosols — small particles in the air that can come from the combustion of fossil fuels — tend to cool surface temperatures. But these emissions have shorter lifetimes, and tend to decrease as technology improves, she said. As that happens, she said, we’re likely to see even stronger warming.

“This paper really takes it to the next level linking these increases in wildfires to the world’s major emissions,” Fu said.

When looking at the relationship between fossil fuels and extreme events, Dahl said it’s important to recognize that the impacts of climate-induced disasters have not been borne equally.

As wildfires in the western United States have grown in size and intensity, and caused unprecedented levels of damage to communities, the public has been left to cover much of the cost through increased taxes and surcharges on utility bills, she said.

“But at the same time, we know that the fossil fuel industry has known for decades how much their products affect our climate, and that the emissions associated with these companies have dramatically altered our climate,” she said. “We really wanted to highlight the fossil fuel industry’s role in driving the worsening wildfires in the West so they could be held accountable for their share of the costs.”

“I think a lot of us in California are used to thinking of corporate accountability for wildfires as limited to Pacific Gas and Electric and the immediate failure of the utilities that ignited some of the largest and deadliest wildfires in the state,” she added. “But the truth is, there is a much larger group of corporate actors that are not being held accountable at all.”

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