Climate Change Increased Likelihood of Conditions Fueling L.A. Fires by 35%, Scientists Report
A new study finds that warmer temperatures due to global warming have made extreme fire conditions in Los Angeles more frequent and severe.
Climate change played a significant role in amplifying the extreme conditions that allowed the recent fires to ravage the Los Angeles area, according to a report released by an international group of scientists on Tuesday.
The hot, dry, and windy conditions leading up to the fires were approximately 35% more likely due to human-driven global warming, the World Weather Attribution group found in their analysis. The fires, which ignited during a powerful windstorm and followed months of little rainfall in the region, have resulted in at least 29 deaths and destroyed over 16,000 buildings, including homes, schools, and businesses.
“This was a perfect storm of conditions for a fire disaster — the climate made the conditions more extreme, the weather fueled the flames, and the dense urban environment was situated right in the path of the fires,” explained John Abatzoglou, a climatology professor at the University of California, Merced, and a contributor to the report.
The report highlights a critical change in the region’s climate: compared to preindustrial times, Los Angeles now experiences an average of 23 additional days of dry season each year. This shift increases the likelihood that fires will coincide with the seasonal Santa Ana winds, which are known for intensifying fires.
Park Williams, a geography professor at UCLA and co-author of the study, outlined the four key conditions for fires to occur during Southern California’s cooler months: dry grass or brush, abnormally dry conditions, an ignition source, and extreme weather events like windstorms. He likened these elements to switches in a system that must all be flipped for a fire disaster to ignite.
“The warming caused by human activities is making these conditions more intense,” Williams said.
The study used weather and climate models to assess how a warming atmosphere is influencing fire risk. One of the metrics tracked by the researchers was the Fire Weather Index, which factors in temperature, humidity, and wind speeds — all of which contribute to the likelihood of wildfire.
The scientists found that the conditions that sparked the recent fires in Los Angeles are now expected to occur about once every 17 years in today’s climate. Without climate change, these conditions would have occurred once every 23 years, and they would have been less severe, according to the report.
World Weather Attribution, a loose group of scientists who rapidly assess climate change’s role in extreme weather events, produced the report. Although their findings are peer-reviewed, this particular study has not undergone the lengthy academic review process typical of most research. Nevertheless, the group's previous work on heatwaves, wildfires, and hurricanes has stood up to scrutiny and has been published in academic journals.
Wildfires are notoriously complex to analyze, and local factors must be carefully considered. While the report underscores that climate change played a significant role in exacerbating fire conditions, it was not the sole factor at play.
The hills surrounding Los Angeles are filled with brush that naturally burns in certain intervals, and human activity — from cigarette butts and power lines to fireworks and vehicles — often serves as the ignition source. Additionally, suburban development has expanded into wildfire-prone areas, turning homes into fuel for the flames and accelerating the spread of fires.
“Fire in Southern California is a highly complex issue,” said Abatzoglou, emphasizing the interplay between the landscape and human activity. “The region’s large population, frequent ignitions, and land-use issues all contribute to the intensity of these fires.”
The report also examined the role of the Santa Ana winds, one of the key contributors to the fires. While some research suggests that these winds could weaken as the climate warms, other studies indicate that the winds may persist or even intensify during the colder months.
“There’s no clear connection between climate change and the winds yet,” Williams explained. “We don’t know of a direct link, but it's a possibility we’re still exploring.”
This study underscores the growing influence of climate change on extreme weather events and serves as a reminder of the increasing risks posed by global warming.