Los Angeles Will Get Drier And More Flammable With Continued Use Of Fossil Fuel

PICTURE COURTESY : LOS ANGELES TIMES

LA will get drier and more flammable with continued fossil fuel burning, scientists warn Human-caused climate change worsened the ferocious Los Angeles wildfires by reducing rainfall, drying out vegetation, and increasing the overlap between flammable drought conditions and strong Santa Ana winds, a rapid analysis has found.

The study was carried out by 32 researchers, including leading wildfire scientists from the US and Europe as part of World Weather Attribution (WWA), which has studied the influence of climate change on more than 90 extreme events around the world. The analysis found:

● The hot, dry and windy conditions that drove the fires were about 35% more likely due to warming caused primarily by the burning of oil, gas and coal

● These fire-prone conditions will become a further 35% more likely if warming reaches 2.6°C, which is expected by 2100

● Low rainfall from October-December is now about 2.4 times more likely compared to the preindustrial climate

● Fire-prone conditions have extended by about 23 extra days each year, increasing the chance a fire will start during peak Santa Ana winds

● Water infrastructure, not designed to fight a rapidly expanding wildfire, was unable to keep up with scale and extreme needs during the Eaton and Palisades wildfires

The researchers note that while the individual results of these analyses show some degree of uncertainty, they point in the same direction, indicating that climate change increased the likelihood of the fires.

Dr Clair Barnes, World Weather Attribution (WWA) Researcher at the Centre for Environmental Policy, Imperial College London, said: “Climate change increased the risk of the devastating LA wildfires. “Drought conditions are more frequently pushing into winter, increasing the chance a fire will break out during strong Santa Ana winds that can turn small ignitions into deadly infernos. “Without a faster transition away from planet-heating fossil fuels, California will continue to get hotter, drier, and more flammable.”

Extreme fires broke out around LA on January 7. Fanned by powerful Santa Ana mountain winds and burning through tinder-dry vegetation, the fires rapidly spread into urban areas. At least 28 people have been killed, more than 10,000 homes have been destroyed, and millions have been affected by toxic smoke. The fires are the most destructive in LA’s history and potentially the costliest in US history. The study found that the hot, dry and windy conditions that drove the LA fires were about 35% (1.35 times) more likely due to climate change. These fire-prone conditions will intensify if countries keep burning fossil fuels. At 2.6°C of warming, which is expected by 2100 under current scenarios, similar fire-weather in January will become a further 35% more likely, making similar extremes about 80% (1.8 times) more likely compared to the 1.3°C cooler pre industrial climate.

The researchers also found the LA wildfire season is becoming longer and more dangerous as fossil fuel emissions heats the climate. Highly flammable drought conditions now last about 23 more days each year on average than in the preindustrial climate, an analysis of historical weather data found. Due to highly variable rainfall, drought conditions can last much longer in some years, the scientists say. October-December rainfall has historically brought an end to the wildfire season. But in recent decades, these rains have decreased. Today, low rainfall across the three months is about 2.4 times more likely in neutral El Niño conditions, and a further 1.8 times more likely in La Niña conditions compared to the preindustrial climate, an analysis of historical weather data found. Hotter air temperatures are also evaporating more moisture from plants, making them easier to burn. Drier, flammable conditions persisting later in the year increases the chance a wildfire will break out during the peak of the Santa Ana winds in December and January, the scientists say. To determine if climate change has helped promote the low October-December rainfall, lengthened fire season, and fire-prone weather, the researchers combined weather data with climate models.

However, the models did not perform well, in part due to the small, mountainous study area and the scattered, sparse rainfall. While the models indicated a climate change influence on the hot, dry, and windy conditions, they did not show a significant impact on rainfall or the fire season’s end date. Despite this, the scientists are confident that climate change is an important driver of the changes, based on existing scientific studies and the real-world weather data analysed, which show an increased likelihood of LA fires. Southern California is well accustomed to wildfires. However, the simultaneous occurrence of two major fires, driven by hurricane-force Santa Ana winds into urban areas, created chaotic and unpredictable conditions that overwhelmed more than 300 pre deployed firefighters, the study highlights. Improving the water system’s ability to support large-scale firefighting efforts and making sure homes in high-risk zones adhere to defensible space buffer zone requirements will help to reduce the risk of repeat disasters, the researchers say. They also emphasise the importance of early warning and evacuation systems as 17 of the 28 deaths occurred in West Altadena, a neighborhood where warnings were delayed compared to other affected areas.

The study was conducted by 32 researchers as part of the World Weather Attribution group, including scientists from universities and meteorological agencies in Brazil, Portugal, the United States, Sweden, the Netherlands, France and the United Kingdom. Prof John Abatzoglou, Professor of Climatology at the University of California Merced, said: “This was a perfect storm of climate enabled and weather driven fires impacting the built environment.

“While Southern California is no stranger to high impact wildfires, the impact of these fires and the timing of these fires in the core of what should be the wet season differentiate this event as an extreme outlier.” Prof Park Williams, Professor of Geography at the University of California, said: “All the pieces were in place for a wildfire disaster – low rainfall, a build-up of tinder-dry vegetation, and strong winds. “All else equal, warmer temperatures from climate change should cause many fuels to be drier than they would have been otherwise, and this is especially true for larger fuels such as those found in houses and yards. “However, the real reason they become disasters is that homes have been built in areas where fast-moving, high-intensity fires are inevitable.

“Communities can’t build back the same because it will only be a matter of years before these burned areas are vegetated again and a high potential for fast-moving fire returns to these landscapes.” Roop Singh, Head of Urban and Attribution at the Red Cross Red Crescent Climate Centre, said: “A deadly combination of factors came together to turn this wildfire into a disaster. “Climate change set the stage, helping turn the hills around LA tinder-dry. However, hurricane-force Santa Ana winds, the rapid spread of fires into urban zones, and a strained water system all made the blazes extremely difficult to contain. “These fires have highlighted just how vulnerable California is to winter wildfires, underscoring the need for better preparation for a more dangerous future.” Theo Keeping, Wildfire Researcher at the Leverhulme Centre for Wildfires, Imperial College London “Using several methods and lines of evidence, this study confirms that climate change made the catastrophic LA wildfires more likely.” “With every fraction of a degree of warming, the chance of extremely dry, easier-to-burn conditions around the city of LA gets higher and higher. “Very wet years with lush vegetation growth are increasingly likely to be followed by drought, so dry fuel for wildfires can become more abundant as the climate warms.”

Dr Friederike Otto, co-lead of World Weather Attribution and Senior Lecturer in Climate Science at Imperial College London, said: “Climate change is continuing to destroy lives and livelihoods in the US. “From violent hurricanes in the east, to nightmarish wildfires in the west, Americans are experiencing the devastating consequences of fossil fuel warming. “In 2025, the choices facing world leaders remain the same – to drill and continue to burn oil, gas and coal and experience ever more dangerous weather, or transition to renewable energy for a safer and fairer world.”

Scientists globally agree that climate change is increasing the risk of wildfires starting and spreading as persistent heat dries out soils and vegetation, creating more flammable conditions. To quantify the effect of climate change on the LA wildfires, the scientists analysed weather data and climate models using peer-reviewed methods to compare how these types of events have changed between today’s climate, with approximately 1.3°C of global warming, and the cooler pre-industrial climate. The study focused on a region of Southern California around LA and included several different analyses to investigate the different ways that human-caused warming may have influenced the fires.

The scientists first analysed the one-day maximum of the Fire Weather Index, a metric that considers the hot, dry and windy conditions that drive wildfires. They then analysed total October-December rainfall, which normally marks the end of the wildfire season in the region. Finally, to investigate how the length of the wildfire season is changing, the scientists analysed when drought conditions end each year using the Drought Code. Santa Ana winds The link between climate change and Santa Ana winds is not well understood. Most studies predict a reduction in these dry mountain winds with climate change. However some suggest hot Santa Ana wind events and years with very strong Santa Ana winds will persist as the climate warms. Scientists also analysed historical records to understand if the weather patterns associated with the extreme Santa Ana winds on January 8 have changed as the climate warms. This analog analysis found that cut-off-lows, which often lead to strong wind events, have increased in winter. The finding supports a number of studies suggesting that some of the most extreme Santa Ana winter winds may continue or intensify.

However, the scientists note that further research is needed to understand how these winds will behave in the long term. Pre-fire conditions and weather whiplash Wildfires are common in Southern California during the summer, but rarer in rainier winter months. This year’s fires followed two wet winters in 2022-23 and 2023-24, which promoted the growth of grass and brush. However, almost no rain this winter caused the plants to remain dry and highly flammable. The extreme swings between very wet or dry conditions, like what occurred in California, are increasing around the world, likely because of climate change, a recent study found.

These ‘weather whiplash’ events are driven by a warmer atmosphere that can absorb and release more moisture. The severe floods in East Africa from October-December 2023, that came after three years of devastating drought in the region are another example of weather whiplash. Both events were intensified by climate change, studies by World Weather Attribution found. World Weather Attribution World Weather Attribution is an international scientific collaboration that analyses and communicates the possible influence of climate change on extreme weather events, such as storms, extreme rainfall, heatwaves, and droughts. The group has completed more than 90 studies around the world using peer-reviewed methods. The Intergovernmental Panel on Climate Change included research by World Weather Attribution to provide evidence that human-caused climate change is already intensifying weather extremes in every region of the world in its Sixth Assessment Report published in March 2023.

The writer of this article is Dr. Seema Javed, an environmentalist & a communications professional in the field of climate and energy