Cascadia Burning: The historic, but not historically unprecedented, 2020 wildfires in the Pacific Northwest,<scp>USA</scp>

Reilly, Matthew J.; Zuspan, Aaron; Halofsky, Joshua S.; Raymond, Crystal L.; McEvoy, Andy; Dye, Alex; Donato, Daniel C.; Kim, John B.; Potter, Brian E.; Walker, Nathan; Davis, Raymond J.; Dunn, Christopher J.; Bell, David M.; Gregory, Matthew J.; Johnston, James D.; Harvey, Brian; Halofsky, Jessica E.; Kerns, Becky K.

doi:10.1002/ecs2.4070

Cited by 49 publications

(43 citation statements)

References 107 publications

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“…20-38 • C. Historic Westside fire occurrence has been closely linked to periods of short-term drought in late summer and fall [52]. Particularly disastrous Westside fires appear to be the result of drought, synoptic east winds, and ignition location [53].…”

Section: Historical Wildfire Datamentioning

confidence: 99%

Hazards of Risk: Identifying Plausible Community Wildfire Disasters in Low-Frequency Fire Regimes

McEvoy

Kerns

Kim³

2021

Forests

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Optimized wildfire risk reduction strategies are generally not resilient in the event of unanticipated, or very rare events, presenting a hazard in risk assessments which otherwise rely on actuarial, mean-based statistics to characterize risk. This hazard of actuarial approaches to wildfire risk is perhaps particularly evident for infrequent fire regimes such as those in the temperate forests west of the Cascade Range crest in Oregon and Washington, USA (“Westside”), where fire return intervals often exceed 200 years but where fires can be extremely intense and devastating. In this study, we used wildfire simulations and building location data to evaluate community wildfire exposure and identify plausible disasters that are not based on typical mean-based statistical approaches. We compared the location and magnitude of simulated disasters to historical disasters (1984–2020) in order to characterize plausible surprises which could inform future wildfire risk reduction planning. Results indicate that nearly half of communities are vulnerable to a future disaster, that the magnitude of plausible disasters exceeds any recent historical events, and that ignitions on private land are most likely to result in very high community exposure. Our methods, in combination with more typical actuarial characterizations, provide a way to support investment in and communication with communities exposed to low-probability, high-consequence wildfires.

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Section: Historical Wildfire Datamentioning

confidence: 99%

Hazards of Risk: Identifying Plausible Community Wildfire Disasters in Low-Frequency Fire Regimes

McEvoy

Kerns

Kim³

2021

Forests

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“…One of the strongest and driest easterly winds recorded since 1948, combined with vegetation that desiccated over the unusually hot and dry preceding weeks, drove the rapid growth of the fires (Abatzoglou et al 2021c, Mass et al 2021, Evers et al 2022. The fire weather, as measured by a combination of heat, aridity, and wind that is consistent with expansion of wildfire, was more extreme over large areas of western Oregon than recorded since 1979 (Hawkins et al 2022), although probably similar to fire weather during other major wildfires in western Oregon before and since European colonization (Abatzoglou et al 2021c, Reilly et al 2022.…”

Section: David Rupp and Andrés Holzmentioning

confidence: 74%

“…Those wildfires eventually burned nearly 4,000 km 2 (~1,500 mi 2 ), mostly forested, including more than 11 percent of the Oregon Cascade Range. The area burned in the western Cascade Range in 2020 equaled or surpassed that in any other year for which records are reliable (Abatzoglou et al 2021c, Reilly et al 2022. One of the strongest and driest easterly winds recorded since 1948, combined with vegetation that desiccated over the unusually hot and dry preceding weeks, drove the rapid growth of the fires (Abatzoglou et al 2021c, Mass et al 2021, Evers et al 2022.…”

Section: David Rupp and Andrés Holzmentioning

confidence: 97%

“…In late summer and autumn and prior to the onset of the autumn rains, particularly strong and dry easterly winds, known colloquially as east winds, promote the rapid spread of wildfire. East winds were key drivers of the largest wildfires on record in western Oregon, including the 2020 Labor Days fires , Mass et al 2021, Reilly et al 2022. Recent research incorporating regional climate models that accounted for the effects of the Cascade Range shed light on the potential human influence on east winds.…”

Section: Projected Changes In Wind Speedsmentioning

confidence: 99%

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Sixth Oregon climate assessment

Fleishman¹

2023

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Consistent with its charge under Oregon House Bill 3543, the Oregon Climate Change Research Institute (OCCRI) conducts a biennial assessment of the state of climate change science, including biological, physical, and social science, as it relates to Oregon and the likely effects of climate change on Oregon. This sixth Oregon Climate Assessment builds on the previous assessments by continuing to evaluate past and projected future changes in Oregon’s climate and water supply. Like the fifth assessment, it is structured with the goal of supporting the state’s mitigation planning for natural hazards and implementation of the 2021 Oregon Climate Change Adaptation Framework.

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“…Higher ERC values are related to greater potential fire intensity. Both EDDI and ERC have strong demonstrated relationships with many wildfire characteristics, including spread rate, intensity and severity (McEvoy et al, 2019; Reilly et al, 2022).…”

Section: Methodsmentioning

confidence: 99%

Spatial interactions among short‐interval fires reshape forest landscapes

Harvey

Buonanduci

Turner

2023

Global Ecol Biogeogr

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Aim Ecological disturbances are increasing as climate warms, and how multiple disturbances interact spatially to drive landscape change is poorly understood. We quantified burn severity across fire regimes in reburned forest landscapes to ask how spatial patterns of high‐severity fire differ between sequential overlapping fires and how landscape heterogeneity is shaped by cumulative disturbance patterns. We also characterized the amount and configuration of an emerging phenomenon: areas burned as high‐severity fire twice in successive fires. Location Northwest USA. Time period 1984–2020. Major taxa studied Forests of western continental USA. Methods We used a field‐calibrated atlas of satellite‐measured burn severity across diverse fire regimes (more than three decades, >200 short‐interval fires) to quantify landscape metrics of high‐severity (>75% tree mortality) fire in sequential overlapping short‐interval fires. We used generalized linear models to test differences in individual and cumulative landscape patterns of burn severity following the first and second fires. Results The amount of severe wildfire and patch size/configuration were generally similar between successive overlapping fires and across fire regimes. However, overlapping individual fires produced cumulative landscape patterns of recent high‐severity fire that were consistently more homogeneous after two fires, with greater distances to remaining mature forest. Additionally, 19–25% of landscapes affected by short‐interval fires burned at high severity in both fires, highlighting the spatial extent of repeatedly and severely disturbed forests. Main conclusions When two individually heterogeneous fires overlap, burn mosaics can fit together like puzzle pieces, whereby twice‐burned landscapes are composed of large and simple‐shaped patches of cumulative recent high‐severity fire interspersed with small patches of mature/old forest. These cumulative spatial outcomes of interacting disturbances can be mechanisms of shifting ecosystem dynamics as global change unfolds and reburns continue.

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Cascadia Burning: The historic, but not historically unprecedented, 2020 wildfires in the Pacific Northwest,USA

Cited by 49 publications

References 107 publications

Hazards of Risk: Identifying Plausible Community Wildfire Disasters in Low-Frequency Fire Regimes

Hazards of Risk: Identifying Plausible Community Wildfire Disasters in Low-Frequency Fire Regimes

Sixth Oregon climate assessment

Spatial interactions among short‐interval fires reshape forest landscapes

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