The rising threats of wildland-urban interface fires in the era of climate change: The Los Angeles 2025 fires
The Los Angeles metropolitan area, home to over 18 million residents, has been surrounded by multiple fast-growing fires since January 7, 2025. As of January 23, these fires are estimated to have burned over 50,000 acres of land and destroyed at least 16,000 structures. Over 180,000 people have been ordered to evacuate, and at least 27 people are reported to have died in these fires. Preliminary estimates suggest that the economic loss of the Los Angeles 2025 fires could exceed 250 billion US dollars. Figure 1 shows the main areas affected by the current wildfires, a comparison with previous major wildfires, and their impacts on air quality.
These fires are only the latest examples of record-breaking fires in the western US and fire-prone regions worldwide. What sets the 2025 Los Angeles fires apart, however, is their proximity to densely populated urban areas. These fires are occurring in areas extremely close to where people live—areas that are also known as the wildland-urban interface (WUI). Because of the fire point locations, these WUI fires are particularly damaging to nearby property and communities, making it difficult for people to evacuate effectively. As of January 23, the Los Angeles fires are already ranked as some of the most destructive fires in terms of the number of structures destroyed in California’s history, despite its smaller burned area compared to past fires (Figures 1C and 1D).
WUI fires are increasing throughout the US, mainly driven by two reasons. First, the WUI is expanding as land-use planning has pushed houses closer to forested areas. The number of houses within wildfire boundaries in the US has doubled since the 1990s.1 In California alone, the number of WUI houses increased by 244,000 in 2020 compared to 2010. Both Pacific Palisades and Altadena—two of the most heavily impacted communities during the 2025 Los Angeles fires—are located in the WUI, according to the US Forest Service. WUI expansions have also increased fire ignition risks from human activities. Second, the warming climate has significantly increased fuel aridity and fire weather risks, which in turn have increased the likelihood of fires in the western US. The 2025 Los Angeles fires are fueled by extreme wind conditions, with wind speeds exceeding 100 miles per hour in certain areas. These strong and dry winds, known as Santa Ana Winds in Southern California, originate from inland areas and often occur in autumn and winter. While these wind patterns are a natural phenomenon in Southern California, they increasingly overlap with hot and dry weather conditions due to climate change, and this dangerous combination creates the perfect conditions for wildfires to spread.2
Wildfires also create substantial damage beyond the immediate fire perimeters. Smoke generated by fires can travel far distances and negatively influence physical and mental health outcomes (Figures 1B and 1E). WUI fires might be particularly damaging to human health, as combustions of building materials release large quantities of smoke with high amounts of toxic elements (e.g., heavy metals) to population centers downwind. Beyond the direct effects on air quality, health, and economic losses, wildfires also release large quantities of greenhouse gases, which further amplify the existing climate feedback, accelerate global warming, and lead to more frequent extreme weather events in the future.
Southern California is not the only place in the world that is experiencing rising threats from WUI fires. In the summer of 2024 alone, two devastating fires also occurred in Portugal and Greece. The Greece wildfires occurred only 22 miles from its capital city, Athens. Global landscape fires (which include wildfires, agricultural fires, and prescribed burning) are estimated to lead to over 1.5 million deaths each year and are projected to continue to rise in future climate.3 While the global mortality estimates associated with WUI fires remain unclear, the health impacts of WUI fires have emerged as an important concern given the rapid increase in burned areas of WUI fires despite a decline in total fire-burned areas.4
Mitigating the threats of WUI fires (and wildfires in general) requires ambitious, innovative, and comprehensive changes in a variety of public policies related to infrastructure, air quality, public health, land management, public awareness, and insurance markets. However, existing policies either do not account for the changing wildfire risks or were designed under outdated fire regimes. For example, air pollution from wildfires is often exempted from air quality regulations under the Clean Air Act, as these events are viewed as beyond the control of local jurisdictions. However, with the increasing contributions of wildfires to ambient air pollution, air quality regulations that consider wildfire pollution impacts and measures to protect public health during wildfire episodes may become necessary. Leading climate change impact assessment tools, such as those models that are used to calculate the monetary benefits of carbon emissions reductions, rarely account for the damages from climate-induced wildfires, despite a recent study finding that this damage is likely among the most costly consequences of a warming climate in the US.5 Energy infrastructures are also widely unprepared for the rising wildfire risks—utility companies in California have already spent billions of dollars to upgrade the energy infrastructure due to the increasing wildfire risks, with the cost inequitably distributed across consumers.
These challenges highlight the urgency of global climate actions to reduce greenhouse gas emissions to limit future warming levels and ultimately control wildfire risks. At the same time, policymakers should prioritize designing and implementing adaptation strategies to increase the community’s resilience to WUI fires and better protect property and human health. These strategies may include expanding fuel treatment measures (such as mechanical thinning and prescribed fires) in WUI, mitigating potential fire risk factors (such as aged power infrastructure), building defensible spaces, house hardening, and improving indoor filtration to protect health when fire and smoke do occur.
