Research Database
Displaying 1 - 20 of 62
Influence of Time‐Averaging of Climate Data on Estimates of Atmospheric Vapor Pressure Deficit and Inferred Relationships With Wildfire Area in the Western United States
Year: 2025
Vapor pressure deficit (VPD) is a driver of evaporative demand and correlates strongly with wildfire extent in the western United States (WUS). Vapor pressure deficit is the difference between saturation vapor pressure (es) and actual vapor pressure (ea). Because es increases nonlinearly with temperature, calculations of time‐averaged VPD vary depending on the frequency of temperature measurements and how ea is calculated, potentially limiting our understanding of fire‐climate relationships. We calculate eight versions of monthly VPD across the WUS and assess their differences. Monthly VPDs…
Publication Type: Journal Article
A Quantitative Analysis of Firefighter Availability and Prescribed Burning in the Okanogan–Wenatchee National Forest
Year: 2025
Wildfire activity in the western United States has been on the rise since the mid-1980s, with longer, higher-risk fire seasons projected for the future. Prescribed burning mitigates the risk of extreme wildfire events, but such treatments are currently underutilized. Fire managers have cited lack of firefighter availability as a key barrier to prescribed burning. We use both principal component analysis (PCA) and logistic regression modeling methodologies to investigate whether or not (and if yes, under what conditions) personnel shortages on a given day are associated with lower odds of a…
Publication Type: Journal Article
Increasing Hydroclimatic Whiplash Can Amplify Wildfire Risk in a Warming Climate
Year: 2025
On January 7 and 8, 2025, a series of wind-driven wildfires occurred in Los Angeles County in Southern California. Two of these fires ignited in dense woody chaparral shrubland and immediately burned into adjacent populated areas–the Palisades Fire on the coastal slopes of the Santa Monica Mountains and the Eaton fire in the foothills of the San Gabriel Mountains. Both fires ultimately eclipsed the traditionally-defined “wildland-urban interface” boundaries by burning structure-to-structure as an urban conflagration. The scope of the devastation is staggering; at the time of writing, the…
Publication Type: Report
Shaping Land Use Patterns in the Wildland-Urban Interface: The Role of State and Local Governments in Reducing Exposure to Wildfire Risks
Year: 2025
Development in the wildland-urban interface is increasing exposure to wildfire risks in the western United States. Yet, among the components of risk—hazard, vulnerability, and exposure—mitigating exposure has arguably been most difficult. In this report, we describe the set of interconnected state and local policies that affect development and risk exposure, including local land use planning and zoning, state policies governing insurance, building codes, and infrastructure spending, as well as the role of states as intermediaries between the federal government and localities. We discuss…
Publication Type: Report
Decreasing frequency of low and moderate fire weather days may be contributing to large wildfire occurrence in the northern Sierra Nevada
Year: 2025
Previous analyses identified large-scale climatic patterns contributing to greater fuel aridity as drivers of recent dramatic increases in wildfire activity throughout California. This study revisits an approach to investigate more local fire weather patterns in the northern Sierra Nevada; a region within California that has experienced exceptionally high wildfire activity recently. The annual percentages of fire season days above 90th and 95th percentile Energy Release Component (ERC) values were very low prior to 1994 (Fig. 3). Since 1994, years with noticeable percentages of exceedances (…
Publication Type: Journal Article
Farming and ranching through wildfire: Producers’ critical role in fire risk management and emergency response
Year: 2025
Wildfires increasingly threaten California’s agricultural sector, posing serious risks to farming, ranching, and food systems. We conducted a survey of 505 California farmers and ranchers affected by wildfires between 2017 and 2023. Main findings show that wildfires’ impacts on producers are extensive and range from mild to catastrophic, with both short and long-term repercussions, regardless of their exposure level. Producers play a central role in community emergency wildfire risk response and management by reducing fuel loads, creating defensible space, and leveraging their fire management…
Publication Type: Journal Article
Mobile radar provides insights into hydrologic responses in burn areas
Year: 2025
Background. Wildfires often occur in mountainous terrain, regions that pose substantial challenges to operational meteorological and hydrologic observing networks. Aims. A mobile, postfire hydrometeorological observatory comprising remote-sensing and in situ instrumentation was developed and deployed in a burnt area to provide unique insights into rainfall-induced post-fire hazards. Methods. Mobile radar-based rainfall estimates were produced throughout the burn area at 75-m resolution and compared with rain gauge accumulations and basin response variables. Key results. The mobile radar was…
Publication Type: Journal Article
Lightning ignition efficiency in Canadian forests
Year: 2025
Background: Lightning-caused fires have a driving influence on Canadian forests, being responsible for approximately half of all wildfires and 90% of the area burned. We created a climatology (2000–2020) of daily lightning efficiency (i.e., the ratio of cloud-to-ground lightning flashes to lightning-caused wildfires that occurred) over the meteorological summer for four ecozones and a subset of British Columbia (BC) ecoprovinces. We estimated lightning efficiency using data from the Canadian Lightning Detection Network and the Canadian National Fire Database. We used the ERA5…
Publication Type: Journal Article
The 2023 wildfires in British Columbia, Canada: impacts, drivers, and transformations to coexist with wildfire
Year: 2025
In 2023, all regions of British Columbia (BC) experienced record-breaking fire weather and wildfires, with extreme behavior and social-ecological effects. In total, 2245 wildfires burned 2840 545 hectares. Contemporary wildfires are the culmination of a century of altered human–forest–wildfire relationships, exacerbated by climate change. Transformative change is urgently needed for the ecosystems and communities to be resilient to wildfire. We present six interrelated strategies needed to amplify the pace and scale of change in response to recent wildfire extremes: (1) Immediately diversify…
Publication Type: Journal Article
Trends in prescribed fire weather windows from 2000 to 2022 in California
Year: 2024
As increasing wildfire activity puts pressure on wildland fire suppression resources both nationally and within the state of California, further development of programs and infrastructure that emphasize preventative fuels treatments, e.g. prescribed burning, is critical for mitigating the impacts of wildfire at large spatial scales. Among many factors that limit the use of prescribed fire, weather and fuel moisture conditions are among the most critical. We analyzed a 2-km gridded hourly surface weather dataset over a 23-yr period to explore the relationship between climatological trends and…
Publication Type: Journal Article
Managed burning of forests: Balancing economic incentives, risks, and liability
Year: 2024
Managed burning of forests can provide benefits to society including mitigated wildfire risk, improved habitat, and more. However, adverse outcomes of escaped fire or smoke pose risks. I reviewed the evolution of the law regulating forest management burns, explored the current legal architecture, and analyzed the economic incentives for involved actors, in order to identify policy options. Liability standards through most of the twentieth century increasingly placed risk burden on landowners and burners, but increased recognition of the benefits of burns led many States to reverse this trend…
Publication Type: Journal Article
Canada Under Fire – Drivers and Impacts of the Record-Breaking 2023 Wildfire Season
Year: 2024
The 2023 wildfire season in Canada was unprecedented in its scale and intensity. Spanning from late April to early November and extending across much of the forested regions of Canada, the season resulted in a record-breaking total area burned of approximately 15 million hectares, over seven times the historic national annual average. The impacts were profound with more than 200 communities evacuated (approximately 232,000 people), periods of dense smoke that caused significant public health concerns, and unprecedented demands on fire-fighting resources. The exceptional area burned can be…
Publication Type: Journal Article
Probabilistic Forecasting of Lightning Strikes over the Continental USA and Alaska: Model Development and Verification
Year: 2024
Lightning is responsible for the most area annually burned by wildfires in the extratropical region of the Northern Hemisphere. Hence, predicting the occurrence of wildfires requires reliable forecasting of the chance of cloud-to-ground lightning strikes during storms. Here, we describe the development and verification of a probabilistic lightning-strike algorithm running on a uniform 20 km grid over the continental USA and Alaska. This is the first and only high-resolution lightning forecasting model for North America derived from 29-year-long data records. The algorithm consists of a large…
Publication Type: Journal Article
Realignment of federal environmental policies to recognize fire’s role
Year: 2024
BackgroundEnactment of the Clean Air Act (CAA), Endangered Species Act (ESA), and National Environmental Policy Act (NEPA), three of the primary federal environmental laws, all coincided with the height of fire suppression and exclusion in the United States. These laws fail to acknowledge or account for the importance of fire in many fire-adapted and fire-dependent ecosystems, particularly in the American west, or the imperative for fire restoration to improve resiliency and reduce wildfire risk as identified by western science and Indigenous knowledge. We review the statutory and regulatory…
Publication Type: Journal Article
Future fire events are likely to be worse than climate projections indicate – these are some of the reasons why
Year: 2024
BackgroundClimate projections signal longer fire seasons and an increase in the number of dangerous fire weather days for much of the world including Australia.AimsHere we argue that heatwaves, dynamic fire–atmosphere interactions and increased fuel availability caused by drought will amplify potential fire behaviour well beyond projections based on calculations of afternoon forest fire danger derived from climate models.MethodsWe review meteorological dynamics contributing to enhanced fire behaviour during heatwaves, drawing on examples of…
Publication Type: Journal Article
The influence of wildfire risk reduction programs and practices on recreation visitation
Year: 2024
Background: The increasing extent and severity of uncharacteristic wildfire has prompted numerous policies and programs promoting landscape-scale fuels reduction. Aims: We used novel data sources to measure how recreation was influenced by fuels reduction efforts under the US Forest Service Collaborative Forest Landscape Restoration (CFLR) Program. Methods: We used posts to four social media platforms to estimate the number of social media user-days within CFLR landscapes and asked: (1) did visitation within CFLR Program landscapes between…
Publication Type: Journal Article
Drought triggers and sustains overnight fires in North America
Year: 2024
Overnight fires are emerging in North America with previously unknown drivers and implications. This notable phenomenon challenges the traditional understanding of the ‘active day, quiet night’ model of the diurnal fire cycle1,2,3 and current fire management practices4,…
Publication Type: Journal Article
Hydrometeorology-wildfire relationship analysis based on a wildfire bivariate probabilistic framework in different ecoregions of the continental United States
Year: 2024
Wildfires are a natural part of the ecosystem in the U.S.. It is vital to classify wildfires using a comprehensive approach that simultaneously considers wildfire activity (the number of wildfires) and burned area. On this basis, the influence of hydrometeorological variables on wildfires can be further analyzed. Therefore, this study first classified wildfire types using a wildfire bivariate probability framework. Then, by considering six hydrometeorological variables, the dominant hydrometeorological variables for different wildfire types in 17 ecoregions of the United States were…
Publication Type: Journal Article
From flexibility to feasibility: identifying the policy conditions that support the management of wildfire for objectives other than full suppression
Year: 2024
Background. Intentional management of naturally ignited wildfires has emerged as a valuable tool for addressing the social and ecological consequences of a century of fire exclusion in policy and practice. Policy in the United States now allows wildfires to be managed for suppression and other than full suppression (OTFS) objectives simultaneously, giving flexibility to local decision makers. Aims. To extend existing research on the history of wildfire management, investigate how wildfire professionals interpret current policy with respect to OTFS management, and better understand how they…
Publication Type: Journal Article
Comparing ground-based lightning detection networks near wildfire points-of-origin
Year: 2024
Lightning detection and attribution to wildfire ignitions is a critical component of fire management worldwide to both reduce hazards of wildfire to values-at-risk and to enhance the potential for wildland fire to provide resource benefits in fire-adapted ecosystems. We compared two operational ground-based lightning detection networks used by fire managers to identify cloud-to-ground strokes within operationally-relevant distances (1.6 km) of the origins of 4408 western United States lightning-ignited wildfires spanning May–September 2020. Applying two sets of constraints–varying…
Publication Type: Journal Article