Climate change made LA fires worse, scientists say

A scientific study has confirmed that climate change is a major factor contributing to the hot, dry weather in the Los Angeles area, which in turn has fueled devastating wildfires. Research from the World Weather Attribution group indicates that climate change has increased the likelihood of these weather conditions occurring by approximately 35%. This organization is renowned for its work linking extreme weather events to climate change.

The study authors point out that the wildfire season in Los Angeles is getting longer, while the rainfall that typically helps extinguish fires is decreasing. Scientists emphasize that these wildfires are complex, with multiple factors at play, but they are confident that global warming is making Los Angeles more susceptible to intense fire events.

Dr. Claire Barnes of Imperial College London, the lead author of the study, stated, "Climate change has increased the risk of devastating wildfires in Los Angeles. Dry conditions are extending more frequently into the winter, increasing the likelihood of fires igniting during strong Santa Ana winds, which can turn small fires into deadly infernos." Santa Ana winds are strong gusts of wind that blow from inland California towards the coast.

The rapidly spreading and extremely destructive fires that broke out in early January have resulted in the deaths of approximately 30 people and the destruction of over 10,000 homes. This new study focuses on the so-called "fire-prone conditions" that can lead to dangerous fires. The research was conducted by a team of researchers from the World Weather Attribution (WWA), a global group that publishes rapid analyses of climate-related weather events.

They used climate models to simulate how warming since the mid-19th century has influenced heatwaves, droughts, floods, and fires. Since the Industrial Revolution, the widespread burning of coal, oil, and gas has released billions of tons of planet-warming gases into the atmosphere. These gases act like a blanket, raising temperatures by approximately 1.2 degrees Celsius.

By using climate models and statistical methods, along with real-world observations, the WWA group has been able to show the extent of global warming's impact on extreme events. In the case of the Los Angeles fires, they found that the hot, dry conditions that led to the fires are expected to occur about once every 17 years. This likelihood has increased by approximately 35% compared to a world that has not experienced warming.

Dr. Friederike Otto, head of the World Weather Attribution group, said, "We actually see that what the models show is very consistent with what we observe [in the real world]. So, on this combined index, we have very high confidence in the results... we actually have a signal where we can say we can definitely attribute this, and also attribute this quantitatively."

Researchers also examined other significant variables that could contribute to wildfires, including the length of the fire season. By analyzing meteorological observations, scientists found that the fire season has increased by about 23 days since the world began to warm (around 1850). The team says this means that dry conditions and Santa Ana winds, which are critical for fire spread, are increasingly overlapping.

Another key factor is drought. Dry conditions in the Los Angeles area between October and December are now about 2.4 times more likely than they were before the large-scale human use of fossil fuels. The researchers made it clear that climate change has increased the likelihood of hot, dry weather that leads to fires. However, the authors were more cautious about the link between rising temperatures and longer fire seasons or reduced rainfall, stating that the models did not show a significant connection.

Despite these reservations, the conclusion is that a warmer world increases the likelihood of devastating wildfires – and these probabilities will continue to rise as more fossil fuels continue to be burned. Professor Gabi Hegerl of the University of Edinburgh (who was not part of the research team) stated, "Overall, the paper finds that climate change makes fires more likely in Los Angeles, despite some statistical uncertainties. This is a carefully researched result that should be taken seriously."

This new work builds on research published while the fires were still raging. That study linked the wildfires to the so-called "[climate whiplash](https://www.bbc.co.uk/news/articles/c0ewe4p9128o)." This effect refers to very wet years being followed almost immediately by very dry years, thus increasing fire risk. This is exactly what happened in Los Angeles, with two wet winters followed by an extremely dry fall and winter this year – the wet weather promoted the growth of grasses and shrubs that became fuel for fires that broke out during strong Santa Ana winds.