Research and Publications
View article.
Protection of human life and property is an accepted priority of wildfire management, yet there has been little consideration of how fire management strategies balance these two objectives. International comparisons present an important opportunity to explore differences in how human life or property are impacted by contrasting wildfire regimes and management responses. We analyse public data (1999–2020) on fatalities and property losses in Australia and the USA, two countries heavily affected by socially disastrous wildfires. The annual ratio between house losses and fatalities differs markedly between the two countries, with the USA experiencing a 2.5-fold higher rate of house loss per fatality than Australia. This difference potentially reflects contrasting wildfire adaptation strategies between these two countries: the USA approach relies on mass evacuations and fire suppression, whereas the Australian approach is centred on building design and reducing wildland fuel loads. Further international comparative research is required to understand how biophysical and management regimes influence the impacts of wildfire on human life and property.
View brief.
It’s no secret that wildland fires kill trees, but are more trees killed by fire when they are already stressed from drought? New research from the U.S. Department of Agriculture, Forest Service indicates that prefire drought can increase tree mortality after fire, even with the same level of tree damage.
View article.
We analyzed fire statistics (1910–2021) alongside climate and weather data, stratifying the state by 10 ecoregions. Northern forests had the strongest correlation with the proximate factor fuel aridity, ultimately due to climate. Fire rotation intervals exceeded 100 years, implicating woody fuel accumulation as an additional factor. Lightning ignitions occurred in decadal bursts, with dense strike events potentially overwhelming fire-fighting resources. Lower elevation/latitude foothill ecoregions experienced highest fire activity following wet winters and springs, implicating control by herbaceous fuel loads and a negative effect of global warming on future fires. Human ignitions dominate in these ecoregions, and population growth contributes to expansion of powerlines, a major ignition source. While climate change may increase fire activity in forested ecoregions, its role is less pronounced in non-forested ecoregions, where human ignition sources are the dominant factor.
View article.
While species diversity and cover of lifeforms did not differ on and off fuel breaks, species composition and regeneration strategy of dominant shrubs differed significantly. Sites in fuel breaks were dominated by fast-growing subshrubs that regenerate from seeds and are more readily dispersed into sites—species that are typical indicators of the coastal sage scrub community. Sites off fuel breaks were characterized by a mix of resprouting and seeding shrubs typically associated with the chaparral community. Fuel breaks established by bulldozers during wildland firefighting have impacts on chaparral composition because the actions of the dozer remove soil seed banks and damage resprout “banks” (lignotubers). The permanence of these changes is likely to be related to the frequency and severity of fire suppression actions.
View article.
The escalating frequency and damage of catastrophic WU fires are accelerating faster than social systems can adapt, presenting disruptive and systemic risks. Among the most pressing: the destabilization of the insurance industry. This crisis stems from a failure to accurately capture and model risk in the built environment, including fire spread into development and the structure-to-structure nature of WU fire loss. To effectively translate wildfire hazard into a quantifiable built environment risk, policymakers and researchers need a comprehensive and collaborative systems approach that prioritizes advanced risk modeling, mandates changes to the built environment through stricter codes, and coordinates efforts across all levels of government and industry. How did we get here? A long-standing desire to reduce perceived threats and increase the value of residential development in fire-prone landscapes perpetuated a cycle of fire exclusion. Aggressively suppressing fire in the western United States has allowed excess flammable vegetation to accumulate, exacerbating hazard. Climate change made things worse by increasing fire activity and fire season duration. Landscapes loaded with highly combustible fuels, including the homes themselves, represent a debt that has become due.
View article.
We evaluated the causes and predictability of four extreme wildfire episodes from the 2024–2025 fire season, including in Northeast Amazonia (January–March 2024), the Pantanal–Chiquitano border regions of Brazil and Bolivia (August–September 2024), Southern California (January 2025), and the Congo Basin (July–August 2024). Anomalous weather created conditions for these regional extremes, while fuel availability and human ignitions shaped spatial patterns and temporal fire dynamics. In the three tropical regions, prolonged drought was the dominant fire enabler, whereas in California, extreme heat, wind, and antecedent fuel build-up were compounding enablers. Our attribution analyses show that climate change made extreme fire weather in Northeast Amazonia 30–70 times more likely, increasing BA roughly 4-fold compared to a scenario without climate change. In the Pantanal–Chiquitano, fire weather was 4–5 times more likely, with 35-fold increases in BA. Meanwhile, our analyses suggest that BA was 25 times higher in Southern California due to climate change. The Congo Basin’s fire weather was 3–8 times more likely with climate change, with a 2.7-fold increase in BA. Socioeconomic changes since the pre-industrial period, including land-use change, also likely increased BA in Northeast Amazonia. Our models project that events on the scale of 2024–2025 will become up to 57 %, 34 %, and 50 % more frequent than in the modern era in Northeast Amazonia, the Pantanal–Chiquitano, and the Congo Basin, respectively, under a medium–high scenario (SSP370) by 2100. Climate action can limit the added risk, with frequency increases held to below 15 % in all three regions under a strong mitigation scenario (SSP126). In Southern California, the future trajectory of extreme fire likelihood remains highly uncertain due to poorly constrained climate–vegetation–fire interactions influencing fuel moisture, though our models suggest that risk may decline in future. This annual report from the State of Wildfires project integrates and advances cutting-edge fire observations and modelling with regional expertise to track changing global wildfire hazard, guiding policy and practice towards improved preparedness, mitigation, adaptation, and societal benefit.
View article.
Climate change is impacting wildfires in the contiguous United States; thus, projections of fire danger under climate change have the potential to inform responses to changing wildfire risks. We calculate fire indices for 13 dynamically downscaled regional climate models, then count days exceeding relevant fire danger thresholds, and compare future changes for mid- and late-twenty-first century relative to a historical reference period. We then compare the responses of the fire indices to highlight areas of agreement and disagreement on the sign and magnitude of future change in fire danger days. Many regions in the domain experience increases in the number of days exceeding fire danger thresholds by the midcentury. The regions which exhibit agreement across the simulation ensemble on the sign of change, and the magnitude of that change, vary greatly between indices. The timing and frequency of fire danger days (defined as days exceeding fire danger thresholds) throughout the year change, both in the shoulder season and during existing peaks in fire danger. By the end of the century, most of the domain experiences statistically significant increases in the number of fire danger days. Complex interactions between input variables, and the sensitivities to inputs, affect the response of fire indices under climate change. The projected increase in fire weather risk could place greater demands upon fire management resources, pose elevated hazards for populations exposed to fire, and potentially disrupt landscapes and infrastructure more frequently.
View article.
Wildfire suppression is shaped by a complex interplay of environmental conditions, resource allocation and management strategies. Examining the containment of the 2021 Schneider Springs Fire in the Eastern Cascades of Washington State, USA, we emphasize critical roles of variable selection, representative sampling and suppression-specific factors. Using descriptive, predictive and causal models, we assessed the influence of weather conditions, terrain features, personnel availability, tree canopy cover, fire containment lines, and previously identified ‘best available’ containment features. High vapor pressure deficit and strong winds were consistently associated with declining containment success. Terrain features such as valleys and ridges facilitated suppression operations, while steep slopes posed challenges. Additional personnel improved containment outcomes, though with diminishing returns in descriptive and predictive models. Tree canopy cover breaks enhanced suppression effectiveness, but with declining utility during windy conditions. Containment lines played a pivotal role, whereas the role of pre-identified containment features was context-dependent, likely influenced by broader strategic decisions. Wildfire containment was influenced by multiple variables, and suppression strategies were situationally determined. Causal models provided valuable insights by isolating total effects of primary variables. Findings underscore adaptive fire management strategies that incorporate context-specific information. Future research should integrate fine-scale weather metrics and additional fire behavior drivers that guide effective decision-making during dynamic operations.
View factsheet.
Across all treatment types, forests that underwent fuel treatments had significantly lower fire severity in three of five metrics (crown scorch percent, crown torch percent, and torch height) and 3x more surviving trees.
View review.
As the use of risk products has grown, so has confusion and controversy about how they work, their strengths and limitations, and the distinction between wildfire risk and wildfire hazard. Wildfire risk products vary widely in their design, purpose, and technical details. They may use different definitions of risk, values, data sources, fire metrics and models. This diversity means that risk assessments for the same location can vary by design. This variability does not necessarily indicate that the products are flawed or inaccurate. Rather, it reflects that wildfire risk analysis is a diverse field with evolving techniques that serve different users and applications. As this comparative review shows, there is no universal formula for assessing wildfire risk. For potential users of wildfire risk products, the strength in understanding diverse approaches lies not in direct comparison but in recognizing the unique contributions each makes. It also means that users need to invest time into selecting the right risk product(s) for their specific application.