U.S. fires became larger, more frequent, and more widespread in the 2000s

Iglesias, Virginia; Balch, Jennifer K.; Travis, William R.

doi:10.1126/sciadv.abc0020

Cited by 111 publications

(72 citation statements)

References 55 publications

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“… 2020 , Norman et al. 2021 , Iglesias 2022 ). In addition, the fact that such extremes were so widely distributed across the globe and touched not only seasonally dry but also moist ecoregions underscores the human significance of these events (Covington and Pyne 2020 ).…”

Section: Contemporary Fire As An Extreme Eventmentioning

confidence: 99%

Systems in Flames: Dynamic Coproduction of Social–Ecological Processes

2022

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Ecologists who study human-dominated places have adopted a social–ecological systems framework to recognize the coproduced links between ecological and social processes. However, many social scientists are wary of the way ecologists use the systems concept to represent such links. This wariness is sometimes due to a misunderstanding of the contemporary use of the systems concept in ecology. We aim to overcome this misunderstanding by discussing the contemporary systems concept using refinements from biophysical ecology. These refinements allow the systems concept to be used as a bridge rather than a barrier to social–ecological interaction. We then use recent examples of extraordinary fire to illustrate the usefulness and flexibility of the concept for understanding the dynamism of fire as a social–ecological interaction. The systems idea is a useful interdisciplinary abstraction that can be contextualized to account for societally important problems and dynamics.

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Section: Contemporary Fire As An Extreme Eventmentioning

confidence: 99%

Systems in Flames: Dynamic Coproduction of Social–Ecological Processes

2022

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“…As a result of fire suppression and climate change, wildfires in the western US are becoming larger and more frequent, leading to deteriorating air quality (Westerling et al, 2006;Dennison et al, 2014;McClure and Jaffe, 2018;Iglesias et al, 2022). While CO and CO 2 dominate biomass burning (BB) emissions, organic compounds are more important in the context of air quality (Andreae and Merlet, 2001;Fine et al, 2004;Permar et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

Emissions of organic compounds from western US wildfires and their near-fire transformations

et al. 2022

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Abstract. The size and frequency of wildfires in the western United States have been increasing, and this trend is projected to continue, with increasing adverse consequences for human health. Gas- and particle-phase organic compounds are the main components of wildfire emissions. Some of the directly emitted compounds are hazardous air pollutants, while others can react with oxidants to form secondary air pollutants such as ozone and secondary organic aerosol (SOA). Further, compounds emitted in the particle phase can volatize during smoke transport and can then serve as precursors for SOA. The extent of pollutant formation from wildfire emissions is dependent in part on the speciation of organic compounds. The most detailed speciation of organic compounds has been achieved in laboratory studies, though recent field campaigns are leading to an increase in such measurements in the field. In this study, we identified and quantified hundreds of gas- and particle-phase organic compounds emitted from conifer-dominated wildfires in the western US, using two two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GC × GC ToF-MS) instruments. Observed emission factors (EFs) and emission ratios are reported for four wildfires. As has been demonstrated previously, modified combustion efficiency (MCE) was a good predictor of particle-phase EFs (e.g., R2=0.78 and 0.84 for sugars and terpenoids, respectively), except for elemental carbon. Higher emissions of diterpenoids, resin acids, and monoterpenes were observed in the field relative to laboratory studies, likely due to distillation from unburned heated vegetation, which may be underrepresented in laboratory studies. These diterpenoids and resin acids accounted for up to 45 % of total quantified organic aerosol, higher than the contribution from sugar and sugar derivatives. The low volatility of resin acids makes them ideal markers for conifer fire smoke. The speciated measurements also show that evaporation of semi-volatile organic compounds took place in smoke plumes, which suggests that the evaporated primary organic aerosol can be a precursor of SOAs in wildfire smoke plumes.

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“…Shifting fire regimes in the western US present escalating management challenges. Though a century of aggressive fire suppression has resulted in an overall deficit of fire (Marlon et al 2012), the annual area burned and incidence of large wildfires (>405 ha) have risen in recent decades (Dennison et al 2014, Westerling 2016, Iglesias et al 2022). Humans have increased ignitions (Balch et al 2017), altered fuel characteristics (Noss et al 2006, Balch et al 2013, Fusco et al 2019), and otherwise modified fire regimes of many western ecosystems, with impacts including permanent vegetation state transitions (D’Antonio and Vitousek 1992, Coop et al 2020) and degradation or loss of habitat for sensitive species (Rockweit et al 2017, O’Neil et al 2020).…”

Section: Introductionmentioning

confidence: 99%

Where there’s smoke, there’s fuel: dynamic vegetation data improve predictions of wildfire hazard in the Great Basin

Smith

et al. 2021

Preprint

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Wildfires are a growing management concern in western US rangelands, where invasive annual grasses have altered fire regimes and contributed to an increased incidence of catastrophic large wildfires. Fire activity in arid, non-forested regions is thought to be largely controlled by interannual variation in fuel amount, which in turn is controlled by antecedent weather. Thus, long-range forecasting of fire activity in rangelands should be feasible given annual estimates of fuel quantity. Using a 32 yr time series of spatial data, we employ machine learning algorithms to predict the relative probability of large (>400 ha) wildfire in the Great Basin based on fine-scale annual and 16-day estimates of cover and production of vegetation functional groups, weather, and multitemporal scale drought indices. We evaluate the predictive utility of these models with a leave-one-year-out cross-validation, building spatial forecasts of fire probability for each year that we compare against actual maps of large wildfires. Herbaceous vegetation aboveground biomass production, bare ground cover, and long-term drought indices were the most important predictors of fire probability. Across 32 fire seasons, >80% of the area burned in large wildfires coincided with predicted fire probabilities ≥0.5. At the scale of the Great Basin, several metrics of fire season severity were moderately to strongly correlated with average fire probability, including total area burned in large wildfires, number of large wildfires, and average and maximum fire size. Our findings show that recent years of exceptional fire activity in the Great Basin were predictable based on antecedent weather and biomass of fine fuels, and reveal a significant increasing trend in fire probability over the last three decades driven by widespread changes in fine fuel characteristics.

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U.S. fires became larger, more frequent, and more widespread in the 2000s

Cited by 111 publications

References 55 publications

Systems in Flames: Dynamic Coproduction of Social–Ecological Processes

Systems in Flames: Dynamic Coproduction of Social–Ecological Processes

Emissions of organic compounds from western US wildfires and their near-fire transformations

Where there’s smoke, there’s fuel: dynamic vegetation data improve predictions of wildfire hazard in the Great Basin

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