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Concept Paper

Defining Extreme Wildfire Events: Difficulties, Challenges, and Impacts

1
Centre for Studies in Geography and Spatial Planning, CEGOT, Geography Department, Faculty of Arts, University of Porto, Porto 4150-564, Portugal
2
Engineering Health Science & Environment, Charles Darwin University, Darwin, Northern Territory 0909, Australia
3
Department of Crop Systems, Forestry and Environmental Sciences, Faculty of Agriculture, University of Basilicata, Potenza 85100, Italy
4
Centre for Research and Technology of Agro-Environment and Biological Sciences, CITAB, University of Trás-os-Montes and Alto Douro, Vila Real 5001-801, Portugal
5
National Research Institute of Science and Technology for Environment and Agriculture, IRSTEA, RECOVER Research Unit, Aix-en-Provence 13100, France
6
Department of Anthropology, University of Georgia, Athens, GA 30602, USA
7
Regional Forest Corps of Sardinia, Cagliari 09131, Italy
8
USDA Forest Service Rocky Mountain Research Station, Fort Collins CO 80526-2098, USA
9
Faculty of Science, University of Alberta, Edmonton, AB T6G 2E9, Canada
10
IDL, Faculty of Sciences, University of Lisbon, Lisbon 1749-016, Portugal
11
Centre for Forest Fire Research (CEIF), ADAI–LAETA, University of Coimbra, Coimbra 3030-289, Portugal
12
Institute of Mediterranean Forest Ecosystems, Hellenic Agricultural Organization "Demeter", Athens 11528, Greece
*
Author to whom correspondence should be addressed.
Retired
Submission received: 15 January 2018 / Revised: 10 February 2018 / Accepted: 14 February 2018 / Published: 25 February 2018

Abstract

:
Every year worldwide some extraordinary wildfires occur, overwhelming suppression capabilities, causing substantial damages, and often resulting in fatalities. Given their increasing frequency, there is a debate about how to address these wildfires with significant social impacts, but there is no agreement upon terminology to describe them. The concept of extreme wildfire event (EWE) has emerged to bring some coherence on this kind of events. It is increasingly used, often as a synonym of other terms related to wildfires of high intensity and size, but its definition remains elusive. The goal of this paper is to go beyond drawing on distinct disciplinary perspectives to develop a holistic view of EWE as a social-ecological phenomenon. Based on literature review and using a transdisciplinary approach, this paper proposes a definition of EWE as a process and an outcome. Considering the lack of a consistent “scale of gravity” to leverage extreme wildfire events such as in natural hazards (e.g., tornados, hurricanes and earthquakes) we present a proposal of wildfire classification with seven categories based on measurable fire spread and behavior parameters and suppression difficulty. The categories 5 to 7 are labeled as EWE.

1. Introduction

1.1. Extraordinary Wildfire Events

Most of the two million wildfire events [1] registered every year worldwide are small in terms of burnt area. However, some become very large incidents that have significant ecological and socio-economic impacts. Examples of the latter include events in China 1987; Portugal 2003 and 2005; Greece, Italy, and the US 2007; Australia 2009; the US 2013; Canada and Chile 2016; and Portugal and the US 2017. These extraordinary wildfires tend to overwhelm suppression capabilities, cause substantial damages, and often result in civilian and firefighter fatalities [1,2,3,4,5]. A significant, recent example is the Pedrógão Grande catastrophic wildfire which occurred in June 2017, in Portugal, with 65 fatalities, more than 200 injured people, and 458 structures completely destroyed from which 41 were first residences and 50 secondary homes [6,7]. This extraordinary event burned 45,328 ha [6], with fireline intensities (FLI) from 20,000 to 60,000 kWm−1 and a rate of spread (ROS) of 65 m/min [7]. Its extreme behavior and impacts resulted from the complex interplay among macro processes (e.g., atmosphere and fire interaction) and local processes and conditions (e.g., poor initial attack, inadequate risk perception, very strong and variable winds, rough topography, low fuel moisture content, fuel load, fuel continuity, landscape connectivity, poor preparedness, and vulnerable communities).
Some argue that such extraordinary wildfires can be seen as the “new normal” since they are increasing in frequency, magnitude and geographic range [8,9] creating a disproportionate impact on the environment and on communities and effecting an array of societal, economic and political concerns [10,11,12]. As discussion has grown around how to respond to these fires, so too has the array of terms used to describe such events. However, no agreement upon terminology and methodology to describe such occurrences has arisen and a clear and commonly accepted definition remains elusive [13]. Some authors use terms reflecting narrow disciplinary approaches that fail to capture the diverse and multifaceted complexity and characteristics of such events; some authors adopt a term without defining it; and some define a term by using too specific geographic quantitative metrics. Despite the different terminology used, the authors are referring to the same type of event. This lack of consistency in terminology and conceptualization creates problems in several areas including difficulties with comparing findings and coordinating research, and communication barriers between operational agencies, policy-makers, and the research community. Developing a clear definition based on non-ambiguous language and objective measurable parameters for these extraordinary wildfire events is needed to build a more robust foundation for research, policy, and operational efforts to identify the most effective approaches and strategies (whether prevention, mitigation, or suppression) to reduce the risk from such outlier fires. The perceived nature of the problem and the precision of its definition can influence the level of decisions and the solutions to be considered [14,15,16]. In an era in which climate change processes are likely to favor the incidence of these extraordinary fires, it becomes even more important to develop a comprehensive definition that follows a transdisciplinary approach.

1.2. The Purpose of the Paper

In the long list of terms used, we believe that extreme wildfire event (hereafter EWE), can best capture the complexity and diversity of the phenomenon, the uncertainty of behavior, and relevant physical, ecological, and social dimensions of extraordinary wildfires. As there is a need to address “how fire really exists, not how select sciences can handle it” ([17]; p. 271), this paper proposes a definition of EWE as a process and an outcome.
This paper will first present a review of the terms used to label extraordinary wildfires and a detailed analysis and discussion of the existing terminology. It then proceeds to explain why EWE is proposed as the best term to designate those events. Next, as extreme is a rather frequent term in scientific literature and operational manuals, the advantages and disadvantages of its use are also explored and we develop a definition of EWE, accompanied by a proposal of a quantitative classification. Finally, we discuss the need to distinguish extreme wildfire event as a physical process from a wildfire disaster, which is defined by socio-economic impacts.

1.3. The Originality and Value of the Paper

Although historically wildfire research “orbited around a physical paradigm of fire” ([17]; p. 271), the originality of this paper lies with its seeking to develop a transdisciplinary analysis of EWE as a complex phenomenon which arises from the interplay between natural and social conditions, processes and factors in all the wildfire temporal phases (i.e., prevention and mitigation, ignition, spread, suppression, impacts, recovery and restoration), as illustrated in Figure 1. It highlights the presence of social aspects in all the phases, even in those that are traditionally considered as merely biophysical ones.
This paper captures the nature of EWE in different cultural and environmental contexts, involving diverse areas of expertise (geography, forestry, engineering, psychology, anthropology, fire sciences, remote sensing, spatial planning, and emergency management), and experience in fire research and firefighting in different parts of the world. The goal is to go beyond drawing on diverse disciplinary perspectives to develop a holistic view [18], ensuring that social and behavioral science perspectives are integrated with those from biophysical sciences (e.g., ecology, forestry, meteorology, climatology), and also involving non-scientific actors. An important outcome of this approach is the appreciation of the collective influence of diverse perspectives in all aspects of fire management.

2. Terminological Review of Extraordinary Wildfires

The plethora of terms used to label extraordinary wildfires made necessary a detailed examination of how they have been used and defined, and the strengths and weaknesses of each one. Terms were identified through the knowledge/expertise of the authors and grouped in four categories: (i) large, very large, and extremely large fire; (ii) megafires; (iii) extreme wildfire event; and (iv) others, composed of a number of disparate terms. An extensive review of the available literature was thus conducted, using as pre-identified keywords such categories. The review considered peer-reviewed, editorial-reviewed literature and permitted to identify a number of publications where the fire categories are described also in terms of measurable variables. Publications that use one of the terms only once and without any clarification of its meaning were excluded from the analysis.

2.1. Large, Very Large and Extremely Large Fires

The terms large wildfire (e.g., [19,20,21]), very large wildfire (e.g., [21,22,23]) or extremely large fire (e.g., [24]) tend to focus on fire size, although the threshold used by the different authors are rarely congruent; for instance, one paper defines extremely large fires (ELFs) using a threshold which is smaller than the one adopted for very large fires (VLFs) in another paper.
The size threshold definitions for large fires (LFs) are subjective and geographically dependent. Some authors prefer to use relative burnt area (BA) thresholds [25,26,27,28] but most of the definitions are based on absolute quantitative thresholds which can change in the course of time, as well as with the geographic area of reference [28,29]. In Europe, thresholds for LFs that have been proposed range from ≥ 100 ha (e.g., [30,31,32,33,34,35,36,37]) to ≥ 1000 ha [38]. In other regions in the world, the threshold ranges from the minimum values of ≥ 20 ha in Arizona (U.S.) [39], to 1000 ha in Australia [40], to 4950 ha in Boreal Shield ecozone of Ontario [41] and to 40,000 ha in the Western United States [42]. The highest thresholds found for a LF were for Eastern Australia with > 41,020 ha [29], for North Australia with > 100,000 ha [43]; for Australia values of 106 ha were considered by Gill and Allan [27].
The size threshold for classifying fires as VLFs is similarly variable from > 1000 ha [44] to > 20,234 ha [23], or ranging from 500 ha to 20,000 ha [45,46].
Extremely Large Fire (ELF) is not a common term. Fernandes et al. [24] consider a minimum threshold of 2500 ha, equivalent to the 99.9th percentile of fire size in Portugal, to be an ELF. Meyn et al. [47] prefer the term large infrequent fires to label the events that are exceptional in their large spatial size, if compared with the fires that usually affect the ecosystems. Schmoldt et al. [48] use the term extensive fire to describe very large wildfires, without reference to specific fire features.
Less frequent definitions use as criterion fire behavior (related to intensity, ROS, and long-distance spotting, which can lead to accelerated fire growth) and its relationship with the complexity of operations and the capacity of suppression [19,21,49].
A final classification approach is based on the stages and complexity of suppression operations [50,51]. Here, both LFs and VLFs require the management and oversight of an organized Incident Management Team (IMT); VLFs are extremely difficult to suppress and would be very likely to do extensive damage to any assets they impact [21].

2.2. Megafires

The term megafire originally appeared to describe the outbreak of large fires in the Western US [17,52,53,54] and, by extension, in other regions of the world [38,55,56]. Megafires has been used to describe fires in forested ecosystems, rangelands [4] and in the wildland or rural urban interface [57] and are commonly understood to be explosive [53], very large, intense, and uncontrollable fires [23].
Megafire, along with the less common terms megablaze [58] and megaburning [17], tends to focus on fire size [59] but, in every country the perception of megafires reflects local conditions. So far, a commonly accepted threshold of size for megafires has not yet been defined, but some values have been proposed. In the US, the National Interagency Fire Center proposes 100,000 acres (40,469 ha) of BA (http://wildfiretoday.com/tag/megafire/), which is the same value for LF by the same organization (https://www.nifc.gov/fireInfo/fireInfo_statistics.html), which may lead to confusion. The EU MEGAFIREs project (ENV4960256, funded under FP4-ENV 2C) proposed a threshold of 500 ha [60] which corresponds to the official limit of LF adopted in Spain [37] and by EFFIS, the European Forest Fire Information System. In Italy, the same value is also proposed [34]. Therefore, it is evident that the fire size threshold to define megafire is very different around the world.
Williams and Hyde [4] and a number of other authors argue that the amount of BA alone does not qualify a wildfire as a megafire, and thus other fire behavior characteristics are required. For instance, the Italian wildfires in summer 2017 were relatively small in size (not exceeding 5000 ha), but because they lasted for more than 10 days instead of being put out quickly, they were perceived by the public and firefighting organizations as megafires. Adams [61] proposes the double criterion of size (>105 ha) and high intensity, without mentioning any intensity threshold. Other authors do not mention size and instead characterize megafires in relation to big intensity, big impacts, and big relief efforts [62].
From the perspective of wildfire control, a megafire is beyond suppression capabilities and efforts, and defeats protection objectives until a major change in weather or fuels occurs [4,5,63].
From the perspective of consequences, megafires transform ecosystems and habitats, have relevant long-lasting social and economic impacts to human society (e.g., loss of livelihood, break-up of communities, loss of amenity and aesthetic value), and have high suppression costs, making them a disaster rather than a larger incident [5,53,64,65]. Megafires have local impacts but can create cascading regional, or even global environmental and human consequences [5].
The disagreement over the parameters used to define megafire makes this term a problematic one. The criteria used to classify megafires are similar to the ones used for the LF group, for example, fire size, behavior, its relationship with operational complexity, and the difficulty of suppression. Thus, megafires, LF, VLFs and ELFs can overlap in their meaning, creating potential for confusion in events description and operational use. The only criterion distinguishing megafire from the others is its impacts (social, economic, and environmental).

2.3. Extreme Wildfire Events

The terms extreme wildfire events (EWEs), extreme wildfire, extreme bushfire event, extreme fire event, and extreme fire are gaining popularity. However, they are not present in FireWords Glossary [66] and other advanced glossaries and their meaning remains ambiguous, hindering clear definition. Sometimes the terms are used without any explanation [67].
In some papers a range of metrics have been used to define extreme wildfire events (EWE) [1,20,21,54,56,68,69]. None of the metrics are present in more than one paper, with the exception of fire size and windy weather (Table 1). The threshold proposed by Oliveri et al. [69] for Alpine Europe is quite low (BA ≥ 105 ha). Lannom et al. [56] propose the adoption of 90th, 95th and 99th percentile of the burned area as the threshold for an EWE. This procedure is not related to a specific value but to a relative context and thus could be accepted worldwide. The majority of authors recognize the complexity of the phenomena and use more than one descriptor to characterize an EWE [1,20,21,54,56].
Some approaches consider EWEs either as individual fires or the coalescence of several fires [1,56], a concept similar to firestorm referred to below. Most of the metrics that have been used to classify a wildfire event as extreme are related to fire behavior and fire environment. McRae [20] recalls fire-atmosphere interactions, and associates extreme fires with a higher level of energy, chaos, and nonlinearity. Bowman et al. [1] adopt fire radiative power. In both situations, the metrics refer to the “during the fire” phase [70]. Other approaches are more focused on EWE as an outcome, classified by its size [69] or impact [1,13,56].
Yet again we find no agreement on the definition of EWE, as the authors do not agree on either the descriptors or their use in absolute or relative terms.

2.4. Other Terms

In this section, the terms were organized in two groups, respectively considering: (i) exceptional fire behavior characteristics such as flares, rapid increase in ROS, anomalous behavior of flames, spotting; and (ii) the consequences of these events.
In the first group terms related with fire behavior characteristics were gathered. A blow-up fire [71,72], is characterized by a sudden change of spread and energy release rates [73]. It has been described as a “rapid transition from a surface fire exhibiting relatively low intensity, to a fire burning in the whole vegetation complex, surface to canopy, and demonstrating dramatically larger flame heights, higher energy release rates, and faster rates of spread” ([74]; p. 67). The Generalized Blaze Flash (GBF), i.e., the instantaneous ignition of a forest area in the whole vegetation, from surface to canopy [75], is categorized as a blow-up fire.
Eruptive fire defines a condition of extreme acceleration of a blow-up fire [28,73] in a limited space and time. In these cases, nearly exponential accelerations may be observed [20,76,77]. Due to their extremely high ROS and intensity, eruptive fires can overwhelm any suppression capacity.
The term conflagration [78], has been used since 1625, mainly for urban fires, as “a raging and destructive fire” ([79]; p. 3) which causes substantial loss of life and property. It can be “any large fire with storm characteristics” ([72]; p. 4) or a fast and large fire exhibiting many of the features associated with extreme fire behavior (EFB) [80]. McRae and Sharples [2] associate conflagrations with violent pyroconvective events in the atmosphere, that produce fire thunderstorms or pyrocumulonimbus (pyroCb).
The terms firestorm, mass fires or area fires have been used for situations occurring when wide areas with high fuel load are burning simultaneously [81]. A firestorm is formed by the coalescence of different individual fires [78,82]. Multiple ignitions caused by lightning or spotting may induce mass fires, which release large amounts of energy [28].
In the second group we considered terms that emphasize the consequences of events more than their size, and behavior. This group includes: catastrophic fires [12,83,84,85,86]; disasters [1,12,86,87,88,89], disaster-fire [28], disastrous fires [90], socially disastrous fires or social disaster [91]; and, socially and ecologically ‘disastrous’ [92]. Frequently, these terms are used without defining them, implicitly considering that the meaning is well known and accepted. Some authors consider just environmental consequences [85] and ecosystem degradation (e.g., irreversible soil losses, losses of dominant or keystone species, loss of biodiversity) [87,88] while others focus on impacts to social systems [86,91]. A few papers focus on the consequences of high-intensity fire behavior both on environmental impacts and on deleterious effects to life and assets [12,84,92]. This second group of terms is the only one that focuses primarily on social factors in their definition.
Overall the terms described in this Section 2.4 use criteria similar to those for defining LF and megafires (erratic fire behavior, difficulty of suppression, severity, and social and economic impacts), so making it hard to distinguish between them.

2.5. Why Select the Term Extreme Wildfire Event?

In examining the list of terms, we argue that extreme wildfire event best captures the nature of outlier wildfires. In part, we argue that, the adjective extreme is most suitable because it describes a threshold situation near the upper ends of the range of observed and expected reality, and also the production of high impacts [93].
The adjective extreme is commonly used in wildfire sciences and management communities to point out, among others, fire danger, fire risk, fire behavior, fire regime, and severity. In Table A2, a non-exhaustive list of examples is reported. For each term a definition (or a description, if the former is missing) and its purpose are given.
While some definitions of extreme are predictive, others refer to a post fire condition, and none of them is inclusive of conditions during and after the event. They are also specific to the particular disciplinary perspectives or organization cultures.
In essence, extreme refers to the top value of a range of categories, and in most cases, it represents values at the extreme tail of a right skewed distribution. When unrelated to a scale of values of a variable, extreme is commonly used as an accretive to emphasize the deviance from the normal range of variability of a phenomenon (e.g., extreme fire phenomena, extreme fire landscape). The term extreme more accurately represents a deviance from the normal and the upper end of a distribution.

3. Conceptualization of Extreme Wildfire Event

3.1. The Constraints of Fire Size

Geographical or cultural criteria should be avoided to establish a definition of EWE that can be used worldwide. Thus, we do not propose wildfire size as a criterion to define EWE for several reasons: (i) it is place-dependent, reflecting landscape characteristics, so it is not possible to establish a commonly accepted and absolute threshold, that accommodates the variety of situations; (ii) size and severity do not have a direct correlation, because the latter depends on the landscape characteristics and fire behavior; (iii) size tells us little about losses and damages which depend on the affected area characteristics, on fire magnitude, and, mainly, on the vulnerability of the exposed population and assets; and (iv) size can also be the result of wildland fire use, which is an accepted fire management practice in areas where naturally caused wildfires are not a threat to assets, homes or people. The definition should be a statement that attributes a distinctive identity and precise meaning to avoid confusion.

3.2. Extreme Wildfire Event as a Process and an Outcome

A standard definition of EWE should not be just focused on categorizing a fire after its occurrence but should be used to anticipate and provide information to better cope with it, emphasizing the importance of forecasting, preventing, and mitigating. Labeling a wildfire event as extreme, using its post fire characteristics, limits its use to research and ex post reconstruction of events, but gives no contribution to operational activities. For this, the definition must also contain the criteria to distinguish and identify the event as extreme as early as possible after its inception, and during the active phase.

3.3. The Definition of Extreme Wildfire Event as a Process and an Outcome

Wildfires are not all the same, and their threat to environment and society increases with the growing magnitude of the physical process that hinders fire control and makes it difficult or impossible, increasing the likelihood of adverse social and environmental impacts. Although consideration of social implications and outcomes of an EWE are a key reason for the need for a consistent definition, there are similar challenges to that of fire size in incorporating social items directly into the definition as social causes and outcomes are too context dependent. Our definition therefore focuses on physical factors of fire behavior that influence capacity to control given that: (i) the greatest likelihood of adverse social impacts is when response abilities are overwhelmed; (ii) suppression abilities are a social variable that can, to a large degree, be assessed consistently across context; and (iii) the physical dynamics that influence fire behavior are the same around the world. (Table 2).
Fire behavior characteristics with potential to have major impacts on people and assets are fireline intensity (FLI), ROS, spotting, and the sudden change of fire behavior. FLI is the pivotal fire behavior parameter as it determines the capacity of control; it can be evaluated from measurements or observations of ROS and fuel consumption [94] or alternatively can be estimated with an acceptable degree of precision from flame length (FL) [95]. FLI can be also approached through the Fire Radiative Power (FRP), although the associated uncertainty is quite high [96]. FLI estimates from FRP can be obtained for ongoing monitored wildfires by remote sensing imagery. Advantages of FRP include: (i) global, daily FRP observations dating to 2001 (MODIS sensor), which could be used to establish an EWE baseline; (ii) FRP is strongly correlated with FLI [96,97] and radiative FLI derived from MODIS thermal data; and (iii) methods for using FRP to quantify intensity differences between fires/regions have been successfully prototyped [98]. A classification system based on FRP observations is far from perfect, but could improve the classification of EWE at the global scale. The values of FLI can be rather deceptive when applied to different fuel types as their structures imply differences in the relationship between flaming front characteristics and FLI [99,100].
A high intensity fire, occurring in heavy fuel and characterized by long and deep flames, generates heat, moisture, gases and particles, under the form of a plume with an upward movement. Smoke, toxic fumes and haze create poor visibility and, consequently hinder evacuation and the use of firefighting aircraft. They are also responsible for short and long-term health problems (e.g., [101,102,103]) and even loss of lives which can occur not only during but also in the aftermath of an event. The upward convective motion of the plume is powered by the amount of energy released by the combustion, integrated by the latent heat released when vapor condensation occurs [104,105,106,107]. The convective activity contributes to changes in the wind speed and wind direction in the immediate vicinity of the fire, caused by the modifications of local winds and creation of inflow into the fire. In addition, it injects steam, smoke, combustion gases and combustion particles into the stratosphere, and launches firebrands into the atmosphere [108], so significantly contributing to extensive spotting. If the amount of energy is enough, the buoyancy of the plume permits its upward convection to the vapor condensation level, with the development of cumuliform cloud tops. In particular conditions of air instability, cloud tops have the shape of pyrocumulus (pyroCu), fire-aided or caused convective clouds, which are rather common, and not a cause of concern [109]. Very rarely pyroCu can evolve to pyroCb [110,111] characterized by considerable vertical development, able to reach heights up to 14 km [6,112] and generating precipitation, downdrafts, and lightning. PyroCu and pyroCb affect smoke lofting and transport [109]. When the vertical upward motion ceases, convective updrafts can reverse and become downdrafts, which hit the ground and spread out, in all directions, so inducing changeable wind direction, and becoming responsible for the strong fire-induced winds often observed at the fire front which may drive erratic fire spread [110], with implications for firefighters’ safety. Rarely, a pyroCb produces downbursts, which are gusty, erratic and intense winds causing unpredictable changes in FLI, FL, ROS, direction of fire spread, and ember spotting [113].
ROS is very dependent on the type of fuel, topography, and weather conditions (especially wind velocity) and influences the fire perimeter extent. An increasing perimeter length requires more human and technological resources to control the fire and can affect the response capacity of suppression crews, which can be rapidly overwhelmed [114]. ROS can reach values of about 333 m/min [115] or even 450 m/min [116] and is considered extreme when it is ≥ 50 m/min [117]. ROS can also have major impacts on the safety of the evacuation process.
Spotting refers to the ignition of new fires, due to downwind ignition of brands, firebrands of bark, or larger embers launched from a primary fire [108,118]. It is strongly dependent on the convective column (induced by fire intensity), and on wind velocity and direction. Short-range spotting can reach up to several tens of meters, intermediate-range spotting can reach up to a few kilometers, while long-range spotting can reach distances of tens of kilometers ahead of the main fire [119]. Spotting distances of up to 25 km from the primary fire were recorded in 1983 in Australia [108] reaching a maximum recorded distance of 33 km in the 2009 Black Saturday bushfires in Victoria (Australia) [84]. Massive spotting activity increases the ROS and thus the area of intervention, requiring more fire suppression resources. It makes fire breaching possible across an extended obstacle to local spread. Massive spotting and high ROS overwhelm displacement capacity. Spotting-dominated cases increase the threatened area and potential losses and damages. [108]. Multiple ignitions from spotting can overwhelm firefighting resources [49] and increase the risk of entrapment for both firefighters and residents (learningcenter.firewise.org/Firefighter-Safety/1-11.php). Control tactics and strategies to anticipate fire behavior, instead of simply following the flames, that might work on large fires (e.g., pre-existing fuel breaks, use of extended attack resources, burning out) are impeded by long-distance spotting, severe turbulence and extremely high ROS [4].
Sudden changes of fire behavior consist of unpredictable variations of fire intensity, erratic ROS and direction, spotting, and occurrence of fire-caused winds. Sudden changes of fire behavior are a significant safety danger to firefighters [120,121] and to population and assets, and can overwhelm suppression efforts.
Another criterion to define EWE is the capacity of control. It is strongly dependent on fire behavior and on place-based technological knowledge and limits (e.g., [19]), particularly the capacity to identify potential spread and intensity of wildfires, and the ability to develop both tactics and strategies (implying identification of objectives and priorities in firefighting, and consequently, tactics and maneuvers). This is more an expression of local levels of organization, resources, and training for firefighters. In the current technological conditions, the accepted limit of capacity to control a fire is 10,000 kWm−1 [122,123,124,125,126]. Beyond 10,000 kWm−1, it is well accepted that even heavy water bombers are ineffective [127], and fire control is not possible with current day technology and technical resources [128]. Long flames also make fires increasingly difficult to control and represent a threat for firefighters who must operate approaching to fire front, but respecting their “safety zone” [74]. With an increasing FLI, the quantity of water to be eventually used as an extinguishing agent to contain flames grows. When FLI is close to the 10,000 kWm−1 threshold, the water amount needed to contain flames is evaluated in 25 to 30 liters every 30 seconds per meter of front [129].
It is important to distinguish cases where it is realistically impossible to cope with a fire, from those where control can theoretically be achieved but lack of needed resources inhibits the ability to do so. In these cases, rather than recognizing the shortfall of the system, the failure of suppression activities may be, inappropriately, justified by labeling them as extreme fires. Such arguments are problematic as they can hide wildfire management weaknesses and failures, thereby decreasing the likelihood of addressing the issue. Failure to suppress a fire due to inadequacy of local fighting crews or lack of training can produce a disaster, even with fires that are not necessarily extreme, such as when wildfires occur in rough territory not well known by suppression crews coming from outside the area. Other failures can result from lack of compliance with safety rules such as LACES protocol (Lookouts; Anchor point or Awareness; Communications; Escape Routes; Safety Zones; [130,131,132]. EWEs, due in large part to their inherent control challenges, can pose more risk for population, assets, and infrastructures, and can provoke entrapments and fire overruns with fatalities.
Hence, EWE is defined as:
a pyro-convective phenomenon overwhelming capacity of control (fireline intensity currently assumed ≥ 10,000 kWm−1; rate of spread >50 m/min), exhibiting spotting distance > 1 km, and erratic and unpredictable fire behavior and spread. It represents a heightened threat to crews, population, assets, and natural values, and likely causes relevant negative socio-economic and environmental impacts.

4. A Preliminary Proposal of Extreme Wildfire Event Classification

Table 3 is a first attempt to build a scale of gravity for wildfires similar to that used for tornados (Fujita scale), and hurricanes (Saffir-Simpson scale). In this wildfire classification, the first four categories are labeled as normal fires (i.e., events within the general capacity of suppression as dictated by technological and physical constraints) ([28]; p. 23), while the other three exceed that threshold and are classified as EWEs, integrating the descriptions of recent extreme wildfire events [84,118] with consolidated literature [125]. The necessity of a scale for wildfires is considered “a worthwhile endeavor” ([21]; p. 50).
The criteria used to establish this classification were real time fire behavior measurable parameters, and real time observable manifestations of EFB. In the former the parameters selected were FLI and ROS and for each category of wildfire quantitative thresholds are considered. In the latter, pyroCb, downdrafts, spotting activity and distance, and flame length (FL) were considered with quantitative and qualitative values. FL is sufficiently easy to assess at the practical operational level [133] and provides a quick assessment of FLI, because of the interdependence of the two parameters [95].
In the proposed EWE classification there is no mention of impacts (environmental, social and economic) because they are highly influenced by the geographic characteristics of the affected area (e.g., WUI, rural space) and its vulnerability to wildfires. The vulnerability concept has been used with different meanings in wildfire literature [134]; it is here defined as the intrinsic characteristics and conditions of population and assets that create the likelihood for negative impacts. It results from the exposure, susceptibility, and capacity to respond to the specific situations. Distinctive degrees of vulnerability create different levels of damages and losses in similar conditions of exposure to wildfires of the same magnitude [135]. This suggests that there is a complex and nonlinear relation between the magnitude of fire and its impacts on society and environment.
Similarly, the use of biophysical parameters to classify EWEs should not be interpreted as a dismissal of the long term and complex social-ecological interactions that cause EWEs and contribute to their outcomes. In many cases, the ultimate causes of EWEs may be almost entirely anthropogenic, from the timing and placement of ignitions to the types and spatial patterning of the fuels, to the climate factors responsible for the conditions of fuels [136,137,138]. However, a scale of gravity for describing wildfire events need not distinguish between the degree of biophysical versus human causes.

5. Extreme Wildfire Event and Wildfire Disaster

Social elements are a fundamental reason for consideration of an EWE definition: if it were not for the potential adverse social impacts of an EWE there likely would be little need to develop a consistent definition. In this respect, we feel it is important to overtly discuss distinctions between an EWE and their potential social impacts. Bowman et al. [1] distinguish between an EWE and a wildfire disaster, where the former is assessed by using a physical measure of fire behavior (i.e., radiative power, FRP in MW/pixel) and the latter by measurable socio-economic impacts (i.e., firefighters or civilian casualties and damage to property and infrastructures) and with reference to institutional procedure (i.e., the official declaration of a disaster by a national government). We agree that EWEs should be operationally differentiated from disasters, because an EWE does not necessarily become a disaster. A wildfire disaster can be the consequence of an EWE, but it can also be the consequence of a controllable phenomenon (a normal wildfire event) because of inadequate management of control actions (e.g., lack of resources, lack of coordination between emergency teams, wrong instructions, wrong evaluation of situations), lack of preparedness by concerned communities, poor land management that has not adequately modified fuel continuity (Figure 2). Conversely, individual large fires simultaneously burning that compete for resources, decrease the likelihood of early fire control and thus increase the chances that any given event will become an EWE or even a disaster [49].
A major consideration in this distinction is the degree to which people and what they value, and rely on for everyday functioning, is significantly affected by an EWE. Whether an EWE becomes a disaster is influenced by what societies and citizens do, individually and collectively, to anticipate sources of risk, act to reduce and manage the risk prior to events occurring, and develop the knowledge, resources, skills and relationships to facilitate their ability to cope with, adapt to and learn from wildfire events. Therefore, the purpose of wildfire management, situated at the interface between society and environment, is to take the necessary steps to avoid the occurrence of EWEs because they are not necessarily an ecological inevitability. In the case of their occurrence, management must ensure that the territory and population are prepared to face them, respond and recover from them. It is thus argued here that an EWEs can turn into a disaster if it directly effects and exceeds the coping and resource capacity of people and communities. This can include the following conditions:
(i) Social impacts. A serious disruption of the functioning of a community or a society at any scale, due to wildfires interacting with conditions of exposure, vulnerability and capacity to cope, leading to human, material, economic and environmental losses and impacts [89,139]. Mayner and Arbon [140] found the most consistent definition of a disaster to be the widespread disruption and damage to a community that exceeds its ability to cope and overwhelms it resources. The affected communities or societies must receive external support to reestablish normal life. The goal is not necessarily to “bounce-back”. In an era of ever-increasing risk, the goal is more about adaptation (e.g., to the social, natural and built environment settings, changed economic conditions, climate change) to emergent realities and transformation (to develop more appropriate approaches to coexistence with fire). It is also important to recognize that disasters can cause direct and indirect impacts, and have both short- and long- term implications.
(ii) Psychological impacts. Disasters are potentially traumatic events that are collectively experienced, and often have an acute onset [141]. Even though a wildfire is a time-delimited event, its effects can be long lasting, and measured over months or years. While enduring trauma, acute stress and post-traumatic stress disorder (PTSD) are fortunately only experienced by a minority of people, stress and traumatic stress are characteristic of all disasters.
Stress and its consequences for wellbeing in people, families and social networks can occur over time, and not just during the period of event impact. Stress reactions are greater if events are perceived to be caused by human agency, especially acts of omission (e.g., failure to plan for a controlled burn that gets out of control) or commission (e.g., arson). Reactions are affected by threats to control beliefs and attributions of responsibility. These reactions can be found in the absence of fatalities and can affect those not present (i.e., those who could have been there, those who used to live in another area). In the case of an EWE occurrence, people do not necessarily die, but their livelihoods and sources of income can be severely disrupted. It is also important to accommodate the fact that the experience of challenging hazard events can transition into posttraumatic growth [142]. Stress triggered when dealing with recovery agencies (response generated demands), organizations, and government departments is greater than that experienced in the immediate aftermath of the event [143,144,145].
The importance of recognizing the direct linkages between the EWE definition and social factors, existing social conditions and potential negative impacts, is needed given the inherent social-ecological nature of wildfire [146,147]. These include the lack of governance systems and planning to cater for events that create large-scale destruction with significant and enduring social and economic disruption [145]. In addition, wildfire disasters create numerous social needs such as:
(i)
need for temporary relocation (which can be measured in months or years while people await rebuilding efforts and this can create conflict from differences in how recovery is managed) or permanent relocation (this removes factors such as sense of community and place attachment, and can generate conflict if people are moved to other settlements);
(ii)
loss of social network connections, so loss of sense of community, and social support;
(iii)
loss of heritage, and community symbols, that threatens, or destroys place attachment and identity.
These demands are more likely with EWEs and so need to be accommodated in how EWEs are conceptualized and how policy and plans are developed and enacted.

6. Conclusion

EWEs are complex social-ecological phenomena requiring a transdisciplinary approach to understand what they really represent. Agreement on a common term and definition to label extraordinary fires is not a minor concern if the scientific community wants to effectively transfer knowledge to enhance wildfire management policies and practice. From the fire management point of view an agreed-on definition can more quickly help to identify fires that will exceed the current capacity of control, where suppression is impossible as long as fuel and weather conditions do not change. From a disaster risk reduction perspective, defining the social and ecological contributions to EWEs is fundamental to developing realistic and comprehensive estimates of risk and how risk can be reduced.
Finally, a clear definition of EWE highlights the fact that not all fires are the same and that some events are beyond the capacity of even well-resourced organizations to control. EWEs are very challenging and costly phenomena but they do not inevitably lead to disasters. Adequate and timely prevention measures can decrease the likelihood of EWEs occurrence, and mitigation activities and preparedness can increase safety and decrease potential losses and damages.
The EWE definition and wildfire classification proposed in this paper can facilitate communication not only within organizations concerned with wildfire management but also with the general public. In particular, the EWE definition allows for more overt recognition of the limits of suppression activities and clarifies key factors that contribute to extreme conditions. This knowledge can help both managers and members of the public identify actions that could best reduce the fire risk for both normal and extreme wildfire events.
This paper addresses the social-ecological topic (or the coupled human natural system topic) in a more appropriate way than many existing efforts. Developing a definition of EWE that incorporated more social elements would not only likely be artificially forcing non-comparable factors together (not dissimilar to categorical vs. ordinal) but also would be unproductive as the definition would be unlikely to be relevant in many contexts and/or have to remain so general that it would have minimal value. Instead, by clearly distinguishing how an EWE can be consistently defined in a way that is socially meaningful (e.g., ability to control) and then drawing out how an EWE can be linked with the broader social aspects defined in the context of disaster, we bring together the social and ecological in a meaningful and appropriate way.

Acknowledgments

This work was prepared in the frame of project FIREXTR- Prevent and prepare society for extreme fire events: the challenge of seeing the “forest” and not just the “trees" (FCT Ref: PTDC/ATPGEO/0462/2014), of which the first author is team leader, co-financed by the European Regional Development Fund (ERDF) through the COMPETE 2020 - Operational Program Competitiveness and Internationalization (POCI Ref: 16702) and national funds by FCT-Foundation for Science and Technology, Portugal. The authors would like to thank the associate editor and the two anonymous reviewers for their constructive comments, which helped us to improve the manuscript. The first author wants to thank Antonio Tedim Pedrosa and Ana P. Tedim for their precious collaboration in preparing figures and tables and technical assistance.

Conflicts of Interest

The authors declare no conflict of interest.

Appendix A

Table A1. Wildfire as a social-ecological process: stages. This table is a more detailed but not exhaustive list of processes, conditions and factors depicted in Figure 1.
Table A1. Wildfire as a social-ecological process: stages. This table is a more detailed but not exhaustive list of processes, conditions and factors depicted in Figure 1.
Dimensions and CategoriesPrevention and MitigationIgnitionSpread and Behavior
HumanProcessesLand management
Forest and fuel management (e.g., controlled burning, defensible space)
Disaster risk reduction (DRR): (i) Vulnerability assessment & reduction; (ii) Risk assessment and communication; localizing knowledge, beliefs and actions; (iii) Enhancing forest resilience; (iv) Enhancing individual, household, and communities’ resilience; and (v) Planning to co-exist with a hazardous environment
Public education & awareness
Training
Preparedness including business continuity planning
Law enforcement
Deforestation
Afforestation
Industrial tree plantation
Allocation of forest to alternative land use
Urban sprawl
Land conversion to crops
Increasing demands for agricultural land
Land clearing for cattle ranching and conversion to pastures
Land abandonment
Slash and burn agriculture
Slash and burn forest removal
Scorched-earth policy (political fires)
Burning of fields and houses as measure to expel occupants
Land use and natural resources conflictuality
Simulation and analysis of fire spread
Operational orders
ConditionsLand use
Land ownership and conflicts
Wildland Urban Interface (WUI)
Rural Urban Interface (RUI)
Prevention infrastructures
Relationship between community and fire management agencies
Personal characteristics and beliefs (e.g., fatalism, outcome expectancy)
Awareness
Knowledge of causes
Early alert
Abandonment of landscape
Landscape connectivity
Prevention infrastructures
Accessibility
Mobility conditions
Defensible space
Multiple contemporary fire occurrence
Firefighting crews’ availability
Operational capacity
FactorsBehavioral, demographic, economic, organizational, political, and sociocultural.
Legacy
Anthropogenic causes (Negligent, intentional, and accidental)
Behavioral, demographic, economic, organizational, political, and sociocultural.
Behavioral, demographic, economic, organizational, political, and sociocultural.
Physical and EcologicalProcessesSecondary successionVegetation curing, shrinkage and wilting
Moisture content of dead and live fuels (FMC & LFMC)
Fire behavior
FMC & LFMC
Vegetation curing, shrinkage and wilting
ConditionsFuel load and continuityDead fine fuel load
Climate and Weather (C&W)
Fuel characteristics (Continuity, size packing, density, moisture content, mineral content, vegetation stage)
C&W
Topography
Fire behavior
FactorsNatural successionNatural causes (Lightning, volcanism, self-combustion, meteorite fall) C&W
Topography
Dimensions and CategoriesSuppressionImpactsRecovery and Restoration
HumanProcessesDefense plans
Organization of resources and means (Incident Command System)
Strategies and tactics
Mopping-up
Communication system
Emergency response
Casualties and injured people
Damages of assets
Community response
Psychological aid
Governance
Livelihoods disruption
Resilience
Reporting damages protocol
Burned area emergency response (BAER): assessment and action
Land management
Planning to co-exist with a hazardous environment
Post fire erosion mitigation
Salvage logging
Rebuilding assets
Livelihoods and businesses continuity
Governance
ConditionsLand use mosaic
Accessibility
Mobility level of knowledge and information
Operational capacity
Communication system
Operational capacity
WUI/RUI
Vulnerability of people and assets
Awareness
Government behavior
Laws and regulations
Financial resources availability
Insurance
Build Fire Smart Territory (FST)
FactorsBehavioral, economic, organizational, political, and sociocultural.Behavioral, demographic, economic, organizational, political, and sociocultural.Behavioral, demographic, economic, organizational, political, and sociocultural.
Physical and Ecological ProcessesChange of fire behaviorSeverity
Biomass consumption
Soil erosion
Surface runoff
Natural regeneration
Resilience
ConditionsAtmosphere instability
Fuel continuity (incl. natural vegetation gaps, e.g., the sea)
Vegetal cover mosaic (including that created by past fires)
Degree of vegetation curing
Vegetation species
Wildfire duration
Evolutionary stage of vegetal cover
Hydrophobicity
Extent and duration of wildfire season
Fire regime
Past -fires
Fire history
FactorsWeather
Topography
C&W
Topography
Soil properties
C&W
Disturbing factors (e.g., animals; short return time of fires)
Table A2. The use of extreme in wildfire literature.
Table A2. The use of extreme in wildfire literature.
FireTermDefinition or Description Scope
Danger and weatherExtreme fire dangerFire danger rating usually includes an Extreme class. In the McArthur Forest Fire Danger Index (FFDI) “Extreme” has been redefined after Black Saturday as being between 75 and 100 [148]. In Europe (EFFIS) the Extreme class threshold for Fire Weather Index is 50 (Canadian FWI System).Informs that conditions are favorable to fast spreading, high-intensity fire of erratic behavior, with the potential to become uncontrollable. Firefighters entrapments and fatalities can result. As a consequence, maximum preparedness (from fire prevention to fire suppression to civil protection) is planned for and implemented.
Extreme fire weather Extreme fire weather days
Extreme weather conditions
Fire weather conditions corresponding to Extreme fire danger or leading up to Extreme fire behavior, usually defined by the tail end of the fire weather distribution, e.g., FFWI (Fosberg Fire Weather Index) exceeding the 90th percentile [149]; days that have a fire danger rating of 50 or greater for at least one of the three-hourly observations [150]; days with air temperature ≥20ºC at 850hPa [35].
Extreme fire days
(red flag days)
The onset, or possible onset, of critical weather and dry fuel conditions leading to rapid or dramatic increases in wildfire activity [151,152].Extreme fire behavior expected for the next 12 to 72 hours, imposing a red flag warning.
Extreme wildfire burning conditionsConditions leading to flame and lofted burning ember (firebrand) exposures, home ignition, and unsuccessful firefighting efforts [153].Defines conditions of extreme fire behavior in order to declare ban of high risk activities, preventing human-caused wildfires and structure fires, protecting the natural environment and ensuring public safety.
BehaviorExtreme fire behaviorComprises one or more of the following: high ROS, prolific crowning and/or spotting, presence of fire whirls, deep pyro-convection. Predictability is difficult because such fires often exercise some degree of influence on their environment and behave erratically, sometimes dangerously” [72,74,82,154,155,156].Fire with intensity >4000 kWm−1 [157].Defines conditions and fire characteristics that preclude methods of direct, or even indirect, fire control.
Extreme fire event
Extreme wildfire event
Extreme bushfire
Conflagrations associated with violent pyroconvective events. These extreme wildfires can produce pyroCb, thus a fire-caused thunderstorm [2,21].
Extreme bushfire: a fire that exhibits deep or widespread flaming in an atmospheric environment conducive to the development of violent pyroconvection, which manifests as towering pyroCu or pyroCb storms [13,20,82,156].)
Definition of extreme wildfire based on local fire-atmosphere interactions.
Extreme fire-induced windsWinds generated by low-pressure regions at the flame front. In case of large fires, with the formation of special clouds called pyro-cumulonimbus (pyro CB) [113,158]. Atmospheric instability descriptors define increased danger in firefighting in relation to continuously changing headfire conditions; unexpected, intense fire behavior on the flanks and back of the fire.
Extreme rates of spreadValue considered extreme: 33 ft /min [159]; 150 ch/h [117] (respectively 10 and 50 m/min. A component of wildfire hazard based on ROS, FL and suppression effectiveness. Allows evaluating whether a fire can be suppressed and which types (and amount) of resources will be effective.
Extreme fire phenomenaA poorly defined term [160,161].NA
Extreme landscape fireA form of natural disaster [12,68,91,162,163,164].NA
Extreme fire (burn) severityFire severity is the overall immediate effect of fire resulting from the downwards and upwards components of heat release [165] and can refer to the loss or decomposition of organic matter [166], and in general to the impacts of fire on vegetation and soil. Recently the concept has been enlarged to social impacts [166,167,168,169,170,171]. Assessment of wildfire impacts. Allows to evaluate the needs of emergency recovery measures and prioritize their distribution within the burned area, as well as to plan other post-fire activities, e.g., salvage logging.
RiskExtreme wildfire hazardHazard assessment based on scoring community design, vegetation, topography, additional rating factors, roofing materials, existing building construction, fire protection, utilities, https://extension.arizona.edu/sites/extension.arizona.edu/files/pubs/az1302.pdfUsed to assist homeowners in assessing the relative wildfire hazard severity around a home, neighborhood, subdivision, or community. The value of extreme is for 84+ points.
Extreme wildfire hazard severityThe maximum severity of fire hazard expected to prevail in Fire Hazard Severity Zones based on fuel, slope and fire weather, http//www.fire.ca.gov/fire_prevention/fire_prevention_wildland_faqsIdentification of maximum severity of fire hazard to define the mitigation strategies to reduce risk.
Extreme wildfire threatThe Wildfire Behavior Threat Class estimates potential wildfire behavior. An Extreme (Red) class consists of forested land with continuous surface fuels that will support intermittent or continuous crown fires [172].Integrates many different aspects of fire hazard and risk and provides spatially-explicit tools for understanding the variables that contribute to wildfire threat.
RegimeExtreme fire regimeThe time series of the largest fire (i.e., area burned) per year [173].Term used for statistical purposes.
Extreme fire seasonsThe period of time when fires typically occur or when they are likely to be of high intensity or burn large expanses [174].Supports fire prevention and preparedness based on fire-promoting conditions (drought, solar radiation, relative humidity, air temperature) that have extreme values, e.g., the 90th percentile.

References

  1. Bowman, D.M.J.S.; Williamson, G.J.; Abatzoglou, J.T.; Kolden, C.A.; Cochrane, M.A.; Smith, A.M.S. Human exposure and sensitivity to globally extreme wildfire events. Nat. Ecol. Evol. 2017. [Google Scholar] [CrossRef] [PubMed]
  2. Mcrae, R.; Sharples, J. Assessing mitigation of the risk from extreme wildfires using MODIS hotspot data. In Proceedings of the 21st International Congress on Modelling and Simulation, Gold Coast, Australia, 29 November–4 December 2015; pp. 250–256. [Google Scholar]
  3. Strauss, D.; Bednar, L.; Mees, R. Do one percent of forest fires cause ninety-nine percent of the damage? For. Sci. 1989, 35, 319–328. [Google Scholar]
  4. Williams, J.T.; Hyde, A.C. The mega-fire phenomenon: Observations from a coarse-scale assessment with implications for foresters, land managers, and policymakers. In Proceedings of the Society of American Foresters 89th National Convention, Orlando, FL, USA, 30 September–4 October 2009. [Google Scholar]
  5. Williams, J.; Albright, D.; Hoffmann, A.A.; Ritsov, A.; Moore, P.F.; De Morais, J.C.M.; Leonard, M.; Miguel-Ayanz, J.S.; Xanthopoulos, G.; van Lierop, P. Findings and Implications from a Coarse-Scale Global Assessment of Recent Selected Mega-Fires. In Proceedings of the 5th International Wildland Fire Conference, Sun City, South Africa, 9–13 May 2011; pp. 1–19. [Google Scholar]
  6. Viegas, D.X.; Figueiredo Almeida, M.; Ribeiro, L.M.; Raposo, J.; Viegas, M.T.; Oliveira, R.; Alves, D.; Pinto, C.; Jorge, H.; Rodrigues, A.; et al. O Complexo de Incêndios de Pedrogão Grande E Concelhos Limítrofes, Iniciado a 17 de Junho de 2017; Universidade de Coimbra: Coimbra, Portugal, 2017.
  7. Comissão Técnica Independente. Análise E Apuramento de Factos Relativos Aos Incêndios Que Ocorreram Em Pedrogão Grande, Castanheira de Pera, Ansião, Alvaiázere, Figueiró Dos Vinhos, Arganil, Góis, Penela, Pampilhosa Da Serra, Oleiros E Sertã, Entre 17 E 24 de Junho de 2017; Assembleia da República: Lisbon, Portugal, 2017. [Google Scholar]
  8. Viegas, D.X. Are extreme forest fires the new normal? The Conversation, 9 July 2013. [Google Scholar]
  9. Daniels, L.; Gray, R.W.; Burton, P.J. Megafires in BC—Urgent Need to Adapt and Improve Resilience to Wildfire; Faculty of Forestry: Vancouver, BC, Canada, 2017. [Google Scholar]
  10. Attiwill, P.M.; Adams, M.A. Mega-fires, inquiries and politics in the eucalypt forests of Victoria, south-eastern Australia. For. Ecol. Manag. 2013, 294, 45–53. [Google Scholar] [CrossRef]
  11. Ryan, K.C.; Opperman, T.S. LANDFIRE—A national vegetation/fuels data base for use in fuels treatment, restoration, and suppression planning. For. Ecol. Manage. 2013, 294, 208–216. [Google Scholar] [CrossRef]
  12. Doerr, S.H.; Santín, C. Global trends in wildfire and its impacts: Perceptions versus realities in a changing world. Philos Trans. R. Soc. B. Biol. Sci. 2016, 371, 20150345. [Google Scholar] [CrossRef] [PubMed]
  13. Sharples, J.J.; Cary, G.J.; Fox-Hughes, P.; Mooney, S.; Evans, J.P.; Fletcher, M.-S.; Fromm, M.; Grierson, P.F.; McRae, R.; Baker, P. Natural hazards in Australia: Extreme bushfire. Clim. Chang. 2016, 139, 85–99. [Google Scholar] [CrossRef]
  14. Pescaroli, G.; Alexander, D. A definition of cascading disasters and cascading effects: Going beyond the “toppling dominos” metaphor. Planet@Risk 2015, 2, 58–67. [Google Scholar]
  15. Fifer, N.; Orr, S.K. The Influence of Problem Definitions on Environmental Policy Change: A Comparative Study of the Yellowstone Wildfires. Policy Stud. J. 2013, 41, 636–653. [Google Scholar] [CrossRef]
  16. Morss, R.E. Problem Definition in Atmospheric Science Public Policy: The Example of Observing-System Design for Weather Prediction. Bull. Am. Meteorol. Soc. 2005, 86, 181–191. [Google Scholar] [CrossRef]
  17. Pyne, S.J. Problems, paradoxes, paradigms: Triangulating fire research. Int. J. Wildl. Fire 2007, 16, 271–276. [Google Scholar] [CrossRef]
  18. Ismail-Zadeh, A.T.; Cutter, S.L.; Takeuchi, K.; Paton, D. Forging a paradigm shift in disaster science. Nat. Hazards 2017, 86, 969–988. [Google Scholar] [CrossRef]
  19. Costa Alcubierre, P.; Castellnou Ribau, M.; Larrañaga Otoxa de Egileor, A.; Miralles Bover, M.; Daniel Kraus, P. Prevention of Large Wildfires Using the Fire Types Concept; Direccio General de Prevencio, Extincio D’incendis I Salvaments, Departament D’interior; Generalitat de Catalunya: Barcelona, Spain, 2011. [Google Scholar]
  20. McRae, R. Extreme Fire: A Handbook; ACT Government and Bushfire Cooperative Research Centre: East Melbourne, VIC, Australia, 2010.
  21. McRae, R.; Sharples, J. A conceptual framework for assessing the risk posed by extreme bushfires. Aust. J. Emerg. Manag. 2011, 26, 47–53. [Google Scholar]
  22. Barbero, R.; Abatzoglou, J.T.; Steel, E.A.; K Larkin, N. Modeling very large-fire occurrences over the continental United States from weather and climate forcing. Environ. Res. Lett. 2014, 9, 124009. [Google Scholar] [CrossRef]
  23. Larkin, N.K.; Abatzoglou, J.T.; Barbero, R.; Kolden, C.; McKenzie, D.; Potter, B.; Stavros, E.N.; Steel, E.A.; Stocks, B.J. Future Megafires and Smoke Impacts—Final Report to the Joint Fire Science Program Project; FSP Project No. 11-1-7-4; Joint Fire Science Program Project: Seattle, WA, USA, 2015.
  24. Fernandes, P.M.; Monteiro-Henriques, T.; Guiomar, N.; Loureiro, C.; Barros, A.M.G.G. Bottom-Up Variables Govern Large-Fire Size in Portugal. Ecosystems 2016, 19, 1362–1375. [Google Scholar] [CrossRef]
  25. Lutz, J.A.; Key, C.H.; Kolden, C.A.; Kane, J.T.; van Wagtendonk, J.W. Fire Frequency, Area Burned, and Severity: A Quantitative Approach to Defining a Normal Fire Year. Fire Ecol. 2011, 7, 51–65. [Google Scholar] [CrossRef]
  26. Romero, F.; Senra, F.V. Grandes Incendios Forestales. Causas Y Efectos de Una Ineficaz Gestión Del Territorio; WWF/Adena: Madrid, Spain, 2006. [Google Scholar]
  27. Gill, A.M.; Allan, G. Large fires, fire effects and the fire-regime concept. Int. J. Wildl. Fire 2008, 17, 688. [Google Scholar] [CrossRef]
  28. Viegas, D.X. Extreme Fire Behaviour. In Forest Management: Technology, Practices and Impact; Bonilla Cruz, A.C., Guzman Correa, R.E., Eds.; Nova Science Publishers: New York, NY, USA, 2012; pp. 1–56. [Google Scholar]
  29. O’Donnell, A.J.; Boer, M.M.; McCaw, W.L.; Grierson, P.F. Scale-dependent thresholds in the dominant controls of wildfire size in semi-arid southwest Australia. Ecosphere 2014, 5, art93–art93. [Google Scholar] [CrossRef]
  30. ICNF. Análise Das Causas Dos Incêndios Florestais—2003–2013; ICNF: Lisbon, Portugal, 2014. [Google Scholar]
  31. Pereira, M.G.; Caramelo, L.; Orozco, C.V.; Costa, R.; Tonini, M. Space-time clustering analysis performance of an aggregated dataset: The case of wildfires in Portugal. Environ. Model. Softw. 2015, 72, 239–249. [Google Scholar] [CrossRef]
  32. Parente, J.; Pereira, M.G.; Tonini, M. Space-time clustering analysis of wildfires: The influence of dataset characteristics, fire prevention policy decisions, weather and climate. Sci. Total Environ. 2016, 559, 151–165. [Google Scholar] [CrossRef] [PubMed]
  33. Tonini, M.; Pereira, M.G.; Parente, J.; Vega Orozco, C. Evolution of forest fires in Portugal: From spatio-temporal point events to smoothed density maps. Nat. Hazards 2017, 85, 1489–1510. [Google Scholar] [CrossRef]
  34. Mancini, L.D.; Barbati, A.; Corona, P. Geospatial analysis of woodland fire occurrence & recurrence in Italy. Ann. Silv. Res. 2017, 41, 41–47. [Google Scholar] [CrossRef]
  35. Cardil, A.; Molina, D.M.; Ramirez, J.; Vega-García, C. Trends in adverse weather patterns and large wildland fires in Aragón (NE Spain) from 1978 to 2010. Nat. Hazards Earth Syst. Sci. 2013, 13, 1393–1399. [Google Scholar] [CrossRef]
  36. Cardil, A.; Salis, M.; Spano, D.; Delogu, G.; Molina Terrén, D. Large wildland fires and extreme temperatures in Sardinia (Italy). iForest Biogeosci. For. 2014, 7, 162–169. [Google Scholar] [CrossRef]
  37. Cubo María, J.E.; Enríquez Alcalde, E.; Gallar Pérez-Pastor, J.J.; Jemes Díaz, V.; López García, M.; Mateo Díez, M.L.; Muñoz Correal, A.; Parra Orgaz, P.J. Los Incendios Forestales En España; Ministerio de Agricultura, Alimentación y Medio Ambiente: Madrid, Spain, 2012. [Google Scholar]
  38. Dimitrakopoulos, A.P.; Vlahou, M.; Anagnostopoulou, C.G.; Mitsopoulos, I.D. Impact of drought on wildland fires in Greece: Implications of climatic change? Clim. Chang. 2011, 109, 331–347. [Google Scholar] [CrossRef]
  39. Dickson, B.G.; Prather, J.W.; Xu, Y.; Hampton, H.M.; Aumack, E.N.; Sisk, T.D. Mapping the probability of large fire occurrence in northern Arizona, USA. Landsc. Ecol. 2006, 21, 747–761. [Google Scholar] [CrossRef]
  40. Bradstock, R.A.; Cohn, J.S.; Gill, A.M.; Bedward, M.; Lucas, C. Prediction of the probability of large fires in the Sydney region of south-eastern Australia using fire weather. Int. J. Wildl. Fire 2009, 18, 932–943. [Google Scholar] [CrossRef]
  41. Beverly, J.L.; Martell, D.L. Characterizing extreme fire and weather events in the Boreal Shield ecozone of Ontario. Agric. For. Meteorol. 2005, 133, 5–16. [Google Scholar] [CrossRef]
  42. Olsen, C.S.; Shindler, B.A. Trust, acceptance, and citizen–agency interactions after large fires: Influences on planning processes. Int. J. Wildl. Fire 2010, 19, 137–147. [Google Scholar] [CrossRef]
  43. Yates, C.P.; Edwards, A.C.; Russell-Smith, J. Big fires and their ecological impacts in Australian savannas: Size and frequency matters. Int. J. Wildl. Fire 2008, 17, 768–781. [Google Scholar] [CrossRef]
  44. Mitsopoulos, I.; Mallinis, G. A data-driven approach to assess large fire size generation in Greece. Nat. Hazards 2017, 88, 1591–1607. [Google Scholar] [CrossRef]
  45. Barbero, R.; Abatzoglou, J.T.; Larkin, N.K.; Kolden, C.A.; Stocks, B. Climate change presents increased potential for very large fires in the contiguous United States. Int. J. Wildl. Fire 2015, 24, 892–899. [Google Scholar] [CrossRef]
  46. Barbero, R.; Abatzoglou, J.T.; Brown, T.J. Seasonal reversal of the influence of El Niño-Southern Oscillation on very large wildfire occurrence in the interior northwestern United States. Geophys. Res. Lett. 2015, 42, 3538–3545. [Google Scholar] [CrossRef]
  47. Meyn, A.; White, P.S.; Buhk, C.; Jentsch, A. Environmental drivers of large, infrequent wildfires: The emerging conceptual model. Prog. Phys. Geogr. 2007, 31, 287–312. [Google Scholar] [CrossRef]
  48. Schmoldt, D.L.; Peterson, D.L.; Keane, R.E.; Lenihan, J.M.; McKenzie, D.; Weise, D.R.; Sandberg, D.V. Assessing the Effects of Fire Disturbance on Ecosystems: A Scientific Agenda for Research and Management; U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station: Portland, OR, USA, 1999.
  49. Castellnou, M.; Miralles, M. The changing face of wildfires. Cris Response. 2009, 5, 56–57. [Google Scholar]
  50. Bartlett, T.; Leonard, M.G.M. The megafire phenomenon: Some Australian perspectives. In The 2007 Institute of Foresters of Australia and New Zealand Institute of Forestry Conference; Institute of Foresters of Australia: Canberra, Australia, 2007. [Google Scholar]
  51. Williams, J. The 1910 Fires a Century Later: Could They Happen Again? In Proceedings of the Inland Empire Society of American Foresters Annual Meeting, Wallace, ID, USA, 20–22 May 2010; pp. 20–22. [Google Scholar]
  52. The Brooking Institution. The Mega-Fire Phenomenon. Towards a More Effective Management Model; The Brooking Institution: Washington, DC, USA, 2005. [Google Scholar]
  53. Heyck-Williams, S.; Anderson, L.; Stein, B.A. Megafires: The Growing Risk to America’s Forests, Communities, and Wildlife; National, W., Ed.; National Wildlife Federation: Washington, DC, USA, 2017. [Google Scholar]
  54. Sampson, R.N.; Atkinson, R.D.; Lewis, J.W. Mapping Wildfire Hazards and Risks; CRC Press: Boca Raton, FL, USA, 2000. [Google Scholar]
  55. Ito, A. Mega fire emissions in Siberia: Potential supply of bioavailable iron from forests to the ocean. Biogeosciences 2011, 8, 1679–1697. [Google Scholar] [CrossRef]
  56. Lannom, K.O.; Tinkham, W.T.; Smith, A.M.S.; Abatzoglou, J.T.; Newingham, B.A.; Hall, T.E.; Morgan, P.; Strand, E.K.; Paveglio, T.B.; Anderson, J.W.; et al. Defining extreme wildland fires using geospatial and ancillary metrics. Int. J. Wildl. Fire 2014, 23, 322–337. [Google Scholar] [CrossRef]
  57. Tedim, F.; Xanthopoulos, G.; Leone, V. Forest Fires in Europe: Facts and Challenges. In Wildfire Hazards, Risks and Disasters; Paton, D., Buergelt, P.T., McCaffrey, S., Tedim, F., Eds.; Elsevier: Amsterdam, The Netherlands, 2015. [Google Scholar] [CrossRef]
  58. Dickinson, T. What Megablazes Tell Us About the Fiery Future of Climate Change. Rolling Stone, 15 September 2015. [Google Scholar]
  59. Binkley, D. Exploring the Mega-Fire Reality 2011: The Forest Ecology and Management Conference. Fire Manag. Today 2012, 72, 15–17. [Google Scholar]
  60. Pereira, J.M.C.; Sousa, A.M.O.; Sá, A.C.L.; Martín, M.P.; Chuvieco, E. Regional-scale burnt area mapping in Southern Europe using NOAA-AVHRR 1 km data. In Remote Sensing of Large Wildfires; Springer: Berlin/Heidelberg, Germany, 1999; pp. 139–155. [Google Scholar]
  61. Adams, M.A. Mega-fires, tipping points and ecosystem services: Managing forests and woodlands in an uncertain future. For. Ecol. Manag. 2013, 294, 250–261. [Google Scholar] [CrossRef]
  62. Liu, Y.; Goodrick, S.; Stanturf, J.T.H.; Liu, Y. Impacts of Mega-Fire on Large U.S. Urban Area Air Quality under Changing Climate; JFSP Project 11-1-7-2; Forest Service, SRS-Ctr for Forest Disturbance Science: Athens, GA, USA, 2013.
  63. Xanthopoulos, G.; Athanasiou, M.; Zirogiannis, N. Use of fire for wildfire suppression during the fires of 2007 in Greece. In Proceedings of the II International Conference on Fire Behaviour and Risk, Alghero, Sardinia, Italy, 26–29 May 2015. [Google Scholar]
  64. French, B.J.; Prior, L.D.; Williamson, G.J.; Bowman, D.M.J.S.J.S. Cause and effects of a megafire in sedge-heathland in the Tasmanian temperate wilderness. Aust. J. Bot. 2016, 64, 513–525. [Google Scholar] [CrossRef]
  65. Williams, J. Exploring the onset of high-impact mega-fires through a forest land management prism. For. Ecol. Manag. 2013, 294, 4–10. [Google Scholar] [CrossRef]
  66. Williams, J.; Albright, D. Findings and implications from a coarse-scale global assessement of recent selected mega-fires. In Proceedings of the 5th International Wildland Fire Conferenceth International Wildland Fire Conference, Sun City, South Africa, 9–13 May 2011. [Google Scholar]
  67. Huang, C.; Lin, Y.-L.; Kaplan, M.L.; Charney, J.J. Synoptic-Scale and Mesoscale Environments Conducive to Forest Fires during the October 2003 Extreme Fire Event in Southern California. J. Appl. Meteorol. Climatol. 2009, 48. [Google Scholar] [CrossRef]
  68. Weber, R.O.; Dold, J.W. Linking landscape fires and local meteorology—A short review. JSME Int J Ser B. 2006, 49. [Google Scholar] [CrossRef]
  69. Oliveri, S.; Gerosa, G.; Pregnolato, M. Report on Extreme Fire Occurrences at Alpine Scale. MANFRED Project—Regional Report on Extreme Fire Occurrences. 2012. Available online: http://www.manfredproject.eu/ (accessed on 14 January 2018).
  70. Jain, T.B.; Pilliod, D.S.; Graham, R.T. Tongue-Tied: Confused meanings for common fire terminology can lead to fuels mismanagement. A new framework is needed to clarify and communicate the concepts. Wildfire Mag. 2004, July/August. 22–26. [Google Scholar]
  71. Diaz, H.F.; Swetnam, T.W. The Wildfires of 1910: Climatology of an Extreme Early Twentieth-Century Event and Comparison with More Recent Extremes. Bull. Am. Meteorol. Soc. 2013, 94, 1361–1370. [Google Scholar] [CrossRef]
  72. Byram, G.M. Atmospheric Conditions Related to Blowup Fires. U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station: Asheville, FL, USA, 1954. [Google Scholar]
  73. Viegas, D.X.; Simeoni, A. Eruptive Behaviour of Forest Fires. Fire Technol. 2011, 47, 303–320. [Google Scholar] [CrossRef] [Green Version]
  74. Butler, B.; Cohen, J. Firefighter Safety Zones: A Theoretical Model Based on Radiative Heating. Int. J. Wildl. Fire 1998, 8, 73. [Google Scholar] [CrossRef]
  75. Chatelon, F.-J.; Sauvagnargues, S.; Dusserre, G.; Balbi, J.-H. Generalized blaze flash, a “Flashover” behavior for forest fires—Analysis from the firefighter’s point of view. Open J. For. 2014, 4, 547–557. [Google Scholar] [CrossRef]
  76. Viegas, D.X. A mathematical model for forest fires blowup. Combust. Sci. Technol. 2004, 177, 27–51. [Google Scholar] [CrossRef]
  77. Viegas, D.X. Parametric study of an eruptive fire behaviour model. Int. J. Wildl. Fire 2006, 15, 169. [Google Scholar] [CrossRef]
  78. Chandler, C.C. A Study of Mass Fires and Conflagrations; U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station: Redding, CA, USA, 1963.
  79. Schmalz, R.F. Conflagrations: Disastrous urban fires. In Natural and Tecnological Disasters: Causes, Effects and Preventive Measures; Majumdar, S.K., Forbes, G.S., Miller, E.W., Schmalz, R.F., Eds.; The Pennsylvania Academy of Science: University Park, PA, USA, 1992; pp. 62–74. [Google Scholar]
  80. Merrill, D.F.; Alexander, M.E. (Eds.) Glossary of Forest Fire Management Terms, 4th ed.; Canadian Committee on Forest Fire Management, National Research Council of Canada: Ottawa, ON, Canada, 1987. [Google Scholar]
  81. Countryman, C.M. Mass Fires and Fire Behavior; U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station: Asheville, FL, USA, 1964.
  82. Werth, P.A.; Potter, B.E.; Clements, C.B.; Finney, M.A.; Goodrick, S.L.; Alexander, M.E.; Cruz, M.G.; Forthofer, J.A.; McAllister, S.S. Synthesis of Knowledge of Extreme Fire Behavior: Volume 1 for Fire Management. U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station: Ogden, UT, USA, 2011. [Google Scholar]
  83. Butry, D.T.; Mercer, D.E.; Prestemon, J.P.; Pye, J.M.; Holmes, T.P. What is the Price of Catastrophic Wildfire? J. For. 2001, 99, 9–17. [Google Scholar]
  84. Cruz, M.G.; Sullivan, A.L.; Gould, J.S.; Sims, N.C.; Bannister, A.J.; Hollis, J.J.; Hurley, R.J. Anatomy of a catastrophic wildfire: The Black Saturday Kilmore East fire in Victoria, Australia. For. Ecol. Manage. 2012, 284, 269–285. [Google Scholar] [CrossRef]
  85. Shvidenko, A.Z.; Shchepashchenko, D.G.; Vaganov, E.A.; Sukhinin, A.I.; Maksyutov, S.S.; McCallum, I.; Lakyda, I.P. Impact of wildfire in Russia between 1998–2010 on ecosystems and the global carbon budget. Dokl Earth Sci. 2011, 441, 1678–1682. [Google Scholar] [CrossRef]
  86. Xanthopoulos, G. Forest fire policy scenarios as a key element affecting the occurrence and characteristics of fire disasters. In Proceedings of the IV International Wildland Fire Conference, Sevilla, Spain, 13–17 May 2007. [Google Scholar]
  87. Pausas, J.G.; Llovet, J.; Rodrigo, A.; Vallejo, R. Are wildfires a disaster in the Mediterranean basin? — A review. Int. J. Wildl. Fire. 2008, 17, 713–723. [Google Scholar] [CrossRef]
  88. Williams, R.J.; Wahren, C.H.; Tolsma, A.D.; Sanecki, G.M.; Papst, W.A.; Myers, B.A.; McDougall, K.L.; Heinze, D.A.; Green, K. Large fires in Australian alpine landscapes: their part in the historical fire regime and their impacts on alpine biodiversity. Int. J. Wildl. Fire 2008, 17, 793–808. [Google Scholar] [CrossRef]
  89. Paveglio, T.B.; Brenkert-Smith, H.; Hall, T.; Smith, A.M.S.S. Understanding social impact from wildfires: Advancing means for assessment. Int. J. Wildl. Fire 2015, 24, 212–224. [Google Scholar] [CrossRef]
  90. Reifsnyder, W.E. Weather and Fire Control Practices-197. In Proceedings of the 10th Tall Timbers Fire Ecology Conference, Fredericton, NB, Canada, 20–21 August 1970; pp. 115–127. [Google Scholar]
  91. Gill, M.; Cary, G. Socially disastrous landscape fires in south-eastern Australia: impacts, responses, implications. In Wildfire and Community: Facilitating Preparedness and Resilience; Paton, D., Tedim, F., Eds.; Charles C Thomas: Springfield, IL, USA, 2012; pp. 14–29. [Google Scholar]
  92. Williams, R.J.; Bradstock, R.A. Large fires and their ecological consequences: Introduction to the special issue. Int. J. Wildl. Fire 2008, 17, 685–687. [Google Scholar] [CrossRef]
  93. Cutter, S.L. The Changing Context of Hazard Extremes: Events, Impacts, and Consequences. J. Extreme Events 2016, 3, 1671005. [Google Scholar] [CrossRef]
  94. Byram, G.M. Forest fire behavior. In Forest Fire: Control and Use; Brown, A.A., Davis, K.P., Eds.; McGraw-Hill: New York, NY, USA, 1959; pp. 90–123. [Google Scholar]
  95. Alexander, M.E.; Cruz, M.G. Interdependencies between flame length and fireline intensity in predicting crown fire initiation and crown scorch height. Int. J. Wildl. Fire 2012, 21, 95–113. [Google Scholar] [CrossRef]
  96. Johnston, J.M.; Wooster, M.J.; Paugam, R.; Wang, X.; Lynham, T.J.; Johnston, L.M. Direct estimation of Byram’s fire intensity from infrared remote sensing imagery. Int. J. Wildl. Fire 2017, 26, 668–684. [Google Scholar] [CrossRef]
  97. Kremens, R.L.; Dickinson, M.B.; Bova, A.S. Radiant flux density, energy density and fuel consumption in mixed-oak forest surface fires. Int. J. Wildl. Fire 2012, 21, 722–730. [Google Scholar] [CrossRef]
  98. Kumar, S.S.; Roy, D.P.; Boschetti, L.; Kremens, R. Exploiting the power law distribution properties of satellite fire radiative power retrievals: A method to estimate fire radiative energy and biomass burned from sparse satellite observations. J. Geophys. Res. 2011, 116, D19303. [Google Scholar] [CrossRef]
  99. Cheney, N.P. Quantifying bushfires. Math. Comput. Model. 1990, 13, 9–15. [Google Scholar] [CrossRef]
  100. Alexander, M.E. Calculating and interpreting forest fire intensities. Can. J. Bot. 1982, 60, 349–357. [Google Scholar] [CrossRef]
  101. Frankenberg, E.; McKee, D.; Thomas, D. Health consequences of forest fires in Indonesia. Demography 2005, 42, 29–109. [Google Scholar] [CrossRef]
  102. Liu, J.C.; Pereira, G.; Uhl, S.A.; Bravo, M.A.; Bell, M.L. A systematic review of the physical health impacts from non-occupational exposure to wildfire smoke. Environ. Res. 2015, 136, 120–132. [Google Scholar] [CrossRef] [PubMed]
  103. Black, C.; Tesfaigzi, Y.; Bassein, J.A.; Miller, L.A. Wildfire smoke exposure and human health: Significant gaps in research for a growing public health issue. Environ. Toxicol. Pharmacol. 2017, 55, 186–195. [Google Scholar] [CrossRef] [PubMed]
  104. Tolhurst, K.G.; Chatto, K. Development, behaviour and threat of a plume-driven bushfire in west-central Victoria. In Development, Behaviour, Threat and Meteorological Aspects of a Plume-Driven Bushfire in West-Central Victoria, Berringa Fire February 25-26, 1995; Chatto, K., Ed.; Fire Management, Dept. of Natural Resources & Environment East Melbourne: East Melbourne, Victoria, Australia, 1999; pp. 1.1–1.21. [Google Scholar]
  105. Harris, S.; Anderson, W.; Kilinc, M.; Fogarty, L. The relationship between fire behaviour measures and community loss: An exploratory analysis for developing a bushfire severity scale. Nat. Hazards 2012, 63, 391–415. [Google Scholar] [CrossRef]
  106. Scott, J. Off the Richter: Magnitude and Intensity Scales for Wildland Fire. In Proceedings of the 3rd International Fire Ecology and Management Congress: Changing Fire Regimes: Context and Consequences, San Diego, CA, USA, 13–17 November 2006. [Google Scholar]
  107. McRae, R. Lessons from Recent Research into Fire in the High Country: Checklist for Fire Observers; Bushfire and Natural Hazards CRC: East Melbourne, VIC, Australia, 2010. [Google Scholar]
  108. Martin, J.; Hillen, T. The Spotting Distribution of Wildfires. Appl. Sci. 2016, 6, 177. [Google Scholar] [CrossRef]
  109. Charney, B.E.; Potter, J.J. Convection and downbursts. Fire Manag. Today 2017, 75, 16–19. [Google Scholar]
  110. Lareau, N.P.; Clements, C.B. Cold Smoke: Smoke-induced density currents cause unexpected smoke transport near large wildfires. Atmos. Chem. Phys. 2015, 15, 11513–11520. [Google Scholar] [CrossRef]
  111. Lareau, N.P.; Clements, C.B. Environmental controls on pyrocumulus and pyrocumulonimbus initiation and development. Atmos. Chem. Phys. 2016, 16, 4005–4022. [Google Scholar] [CrossRef]
  112. Cunningham, P.; Reeder, M.J. Severe convective storms initiated by intense wildfires: Numerical simulations of pyro-convection and pyro-tornadogenesis. Geophys. Res. Lett. 2009, 36, L12812. [Google Scholar] [CrossRef]
  113. Tory, W.; Thurston, K.J. Pyrocumulonimbus: A Literature Review; Bushfire and Natural Hazards CRC: East Melbourne, VIC, Australia, 2015. [Google Scholar]
  114. Alexander, M.E.; Cruz, G.M. The elliptical shape and size of wind-driven crown fires. Fire Manag. Today 2014, 73, 28–33. [Google Scholar]
  115. Cruz, M.; Gould, J.S.; Alexander, M.E.; Sullivan, A.L.; McCaw, W.L.; Matthews, S. A Guide to Rate of Fire Spread Models for Australian Vegetation; Australasian Fire and Emergency Service Authorities Council Ltd. and Commonwealth Scientific and Industrial Research Organisation: Canberra, ACT, Australia, 2015. [Google Scholar]
  116. Viegas, D.X.; Raposo, J.R.; Davim, D.A.; Rossa, C.G. Study of the jump fire produced by the interaction of two oblique fire fronts. Part 1. Analytical model and validation with no-slope laboratory experiments. Int. J. Wildl. Fire 2012, 21, 843–856. [Google Scholar] [CrossRef]
  117. Scott, J.H.; Burgan, R.E. Standard Fire Behavior Fuel Models: A Comprehensive Set for Use with Rothermel’s Surface Fire Spread Model; U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station: Portland, OR, USA, 2005. [CrossRef]
  118. Tolhurst, K.G.; Chong, D.M. Incorporating the Effect of Spotting into Fire Behaviour Spread Prediction Using PHOENIX-Rapidfire; Bushfire CRC Ltd.: East Melbourne, VIC, Australia, 2009. [Google Scholar]
  119. Albini, F.A. Potential Spotting Distances from Wind-Driven Surface Fires; U.S. Department of Agriculture, Forest Service, Intermountain Forest and Range Experiment Station: Ogden, UT, USA, 1983.
  120. Pinto, C.; Viegas, D.; Almeida, M.; Raposo, J. Fire whirls in forest fires: An experimental analysis. Fire Saf. J. 2017, 87, 37–48. [Google Scholar] [CrossRef]
  121. Forthofer, J.M.; Goodrick, S.L. Review of Vortices in Wildland Fire. J. Combust. 2011, 2011, 1–14. [Google Scholar] [CrossRef]
  122. Fernandes, P.M.; Botelho, H.S. A review of prescribed burning effectiveness in fire hazard reduction. Int. J. Wildl. Fire 2003, 12, 117–128. [Google Scholar] [CrossRef]
  123. Hirsch, K.; Martell, D. A review of initial attack fire crew productivity and effectiveness. Int. J. Wildl. Fire 1996, 6, 199–215. [Google Scholar] [CrossRef]
  124. Alexander, M.E.; De Groot, W.J. Fire Behavior in Jack Pine Stands as Related to the Canadian Forest Fire Weather Index (FWI) System; Canadian Forestry Service, Northwest Region: Edmonton, AB, Canada, 1988. [Google Scholar]
  125. Alexander, M.E.; Lanoville, R.A. Predicting Fire Behavior in the Black Spruce-Lichen Woodland Fuel Type of Western and Northern Canada. Forestry Canada, Northern Forestry Center: Edmonton, AB, Canada.
  126. Alexander, M.E.; Cole, F.V. Predicting and interpreting fire intensities in Alaskan black spruce forests using the Canadian system of fire danger rating. Managing Forests to Meet People’s Needs. In Proceedings of the 1994 Society of American Foresters/Canadian Institute of Forestry Convention, Bethesda, MD, USA, 18–22 September 1994; pp. 185–192. [Google Scholar]
  127. Wotton, B.M.; Flannigan, M.D.; Marshall, G.A. Potential climate change impacts on fire intensity and key wildfire suppression thresholds in Canada. Environ. Res. Lett. 2017, 12, 95003. [Google Scholar] [CrossRef]
  128. Bushfire and Natural Hazards CRC. Bushfire Research Response Interim Report; Bushfire and Natural Hazards CRC: East Melbourne, VIC, Australia, 2009. [Google Scholar]
  129. Chevrou, R. Incendies de Forêts Catastrophes; Conseil General du Genie Rural, des Eaux et des Forêts: Paris, France, 2000. [Google Scholar]
  130. Alexander, M.E.; Thorburn, W.R. LACES: Adding an “A” for Anchor point(s) to the LCES wildland firefighter safety system. In Current International Perspectives on Wildland Fires, Mankind and the Environment; Butler, B.W., Mangan, R.J., Eds.; Nova Science Publishers Inc.: New York, NY, USA, 2015; pp. 121–144. [Google Scholar]
  131. Stacey, R. European Glossary for Wildfires and Forest Fires, European Union-INTERREG IVC, 2012.
  132. Teie, WC. Firefighter’s Handbook on Wildland Firefighting: Strategy, Tactics and Safety; Deer Valley Press: Rescue, CA, USA, 1994. [Google Scholar]
  133. Barboni, T.; Morandini, F.; Rossi, L.; Molinier, T.; Santoni, P.-A. Relationship Between Flame Length and Fireline Intensity Obtained by Calorimetry at Laboratory Scale. Combust. Sci. Technol. 2012, 184, 186–204. [Google Scholar] [CrossRef]
  134. Tedim, F. O contributo da vulnerabilidade na redução do risco de incêndio florestal. In Riscos Naturais, Antrópicos e Mistos. Homenagem ao Professor Doutor Fernando Rebelo; Lourenço, L., Mateus, M.A., Eds.; Departamento de Geografia, Faculdade de Letras, Universidade de Coimbra: Coimbra, Portugal, 2013. [Google Scholar]
  135. Wisner, B.; Gaillard, J.C.; Kelman, I. Handbook of Hazards and Disaster Risk Reduction; Routledge: London, UK, 2012. [Google Scholar]
  136. Vitousek, P.M. Human Domination of Earth’s Ecosystems. Science 1997, 277, 494–499. [Google Scholar] [CrossRef]
  137. Bond, W.; Keeley, J. Fire as a global “herbivore”: The ecology and evolution of flammable ecosystems. Trends Ecol. Evol. 2005, 20, 387–394. [Google Scholar] [CrossRef] [PubMed]
  138. Coughlan, M.R.; Petty, A.M. Linking humans and fire: A proposal for a transdisciplinary fire ecology. Int. J. Wildl. Fire 2012, 21, 477–487. [Google Scholar] [CrossRef]
  139. United Nations Disaster Relief Organization (UNISDR). Terminology on Disaster Risk Reduction; United Nations International Strategy for Disaster Risk Reduction: Geneva, Switzerland, 2009. [Google Scholar]
  140. Mayner, L.; Arbon, P. Defining disaster: The need for harmonisation of terminology. Australas. J. Disaster Trauma Stud. 2015, 19, 21–26. [Google Scholar]
  141. McFarlane, A.; Norris, F. Definitions and concepts in disaster research. In Methods for Disaster Mental Health Research; Norris, F., Galea, S., Friedman, M., Watson, P., Eds.; Guilford Press: New York, NY, USA, 2006; pp. 3–19. [Google Scholar]
  142. Tedeschi, R.G.; Calhoun, L.G. Routes to posttraumatic growth through cognitive processing. In Promoting Capabilities to Manage Posttraumatic Stress: Perspectives on Resilience; Paton, D., Violanti, J.M., Smith, L.M., Eds.; Charles C. Thomas: Springfield, IL, USA, 2003; pp. 12–26. [Google Scholar]
  143. Quarantelli, E.L. Social Aspects of Disasters and Their Relevance to Pre-Disaster Planning; University of Delaware, Disaster Research Center: Newark, DE, USA, 1976. [Google Scholar]
  144. Quarantelli, E.L.; Dynes, R.R. Response to Social Crisis and Disaster. Annu. Rev. Sociol. 1977, 3, 23–49. [Google Scholar] [CrossRef]
  145. Paton, D.; Jonhston, D.; Mamula-Seadon, L.; Kenney, C.M. Recovery and Development: Perspectives from New Zealand and Australia. In Disaster and Development: Examining Global Issues and Cases; Kapucu, N., Liou, K.T., Eds.; Springer International Publishing: Cham, Switzerland, 2014; pp. 255–272. [Google Scholar]
  146. Paton, D.; Buergelt, P.T.; Tedim, F.; McCaffrey, S. Wildfires: International perspectives on their social-ecological implications. In Wildfire Hazards, Risks and Disasters; Paton, D., Buergelt, P.T., Tedim, F., McCaffrey, S., Eds.; Elsevier: London, UK, 2015; pp. 1–14. [Google Scholar]
  147. Paton, D.; Buergelt, P.T.; Flannigan, M. Ensuring That We Can See the Wood and the Trees: Growing the capacity for ecological wildfire risk management. In Wildfire Hazards, Risks and Disasters; Paton, D., Buergelt, P.T., McCaffrey, S., Tedim, F., Eds.; Elsevier: London, UK, 2015; pp. 247–262. [Google Scholar] [CrossRef]
  148. Australian Emergency Management Committee (AEMC)—National Bushfire Warnings Taskforce. Australia’s Revised Arrangements for Bushfire Advice and Alerts; Version 1.1; Australian Emergency Management Committee: Perth, WA, Australia, 2009. [Google Scholar]
  149. Crimmins, M.A. Synoptic climatology of extreme fire-weather conditions across the southwest United States. Int. J. Climatol. 2006, 26, 1001–1016. [Google Scholar] [CrossRef]
  150. Long, M. A climatology of extreme fire weather days in Victoria. Aust. Met. Mag. 2006, 55, 3–18. [Google Scholar]
  151. Rawson, J.; Whitmore, J. The Handbook: Surviving and Living with Climate Change; Transit Lounge: Melbourne, VIC, Australia, 2015. [Google Scholar]
  152. Benson, R.P.; Corbin, G. A model to predict red flag warning days. In Proceedings of the American Meteorology Society Seventh Symposium on Fire and Forest Meteorology, Bar Harbor, ME, USA, 23–25 October 2007. [Google Scholar]
  153. Calkin, D.E.; Cohen, J.D.; Finney, M.A.; Thompson, M.P. How risk management can prevent future wildfire disasters in the wildland-urban interface. Proc. Natl. Acad. Sci. USA 2014, 111, 746–751. [Google Scholar] [CrossRef] [PubMed]
  154. Butler, B.W.; Bartlette, R.A.; Bradshaw, L.S.; Cohen, J.D.; Andrews, P.L.; Putnam, T.; Mangan, R.J. Fire Behavior Associated with the 1994 South Canyon Fire on Storm King Mountain, Colorado; U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station: Fort Collins, CO, USA, 1998.
  155. Rothermel, R.C. How to Predict the Spread and Intensity of Forest and Range Fires; U.S. Department of Agriculture, Forest Service, Intermountain Research Station: Ogden, UT, USA, 1983.
  156. Werth, P.A.; Potter, B.E.; Alexander, M.E.; Clements, C.B.; Cruz, M.G.; Finney, M.A.; Forthofer, J.M.; Goodrick, S.L.; Hoffman, C.; Jolly, W.M.; et al. Synthesis of Knowledge of Extreme Fire Behavior: Volume 2 for Fire Behavior Specialists, Researchers, and Meteorologists; U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station: Portland, OR, USA, 2016.
  157. Fogarty, L.G. Two rural/urban interface fires in the Wellington suburb of Karori: assessment of associated burning conditions and fire control strategies. FRI Bull. 1996, 197, 16. [Google Scholar]
  158. Department of Fire and Emergency Services (DFES). The Effects of Pyrocumulonimbus on Fire Behaviour and Management; Government of Western Australia: Perth, WA, Australia, 2017.
  159. U.S. Forest Services. Six Rivers National Forest (N.F.), Orleans Community Fuels Reduction and Forest Health Project: Environmental Impact Statement; Orleans Community Fuels Reduction and Forest Health Project: Environmental Impact Statement; New Orleans, LA, USA, 2008. [Google Scholar]
  160. Gomes da Cruz, M. Modeling the Initiation and Spread of Crown Fires. Master Thesis, University of Montana, Missoula, MT, USA, 1999. [Google Scholar]
  161. Rothermel, R.C. Predicting Behavior and Size of Crown Fires in the Northern Rocky Mountains; U.S. Department of Agriculture, Forest Service, Intermountain Research Station: Ogden, UT, USA, 1991. [Google Scholar]
  162. Gill, A.M. Landscape fires as social disasters: An overview of ‘the bushfire problem’. Glob. Environ. Change Pt B: Environ. Hazards 2005, 6, 65–80. [Google Scholar] [CrossRef]
  163. McKenzie, D.; Miller, C.; Falk, D.A. Toward a Theory of Landscape Fire. In The Landscape Ecology of Fire; Springer: Berlin, Germany, 2011; pp. 3–25. [Google Scholar]
  164. Gill, A.M.; Mckenna, D.J.; Wouters, M.A. Landscape Fire, Biodiversity Decline and a Rapidly Changing Milieu: A Microcosm of Global Issues in an Australian Biodiversity Hotspot. Land 2014, 3, 1091–1136. [Google Scholar] [CrossRef]
  165. Ryan, K.C.; Nost, N.C. Evaluating Prescribed Fires; U.S. Department of Agriculture, Forest Service, Intermountain Forest and Range Experiment Station: Ogden, UT, USA, 1985.
  166. Keeley, J.E. Fire intensity, fire severity and burn severity: A brief review and suggested usage. Int. J. Wildl. Fire 2009, 18, 116–126. [Google Scholar] [CrossRef]
  167. Chafer, C.J.; Noonan, M.; Macnaught, E. The post-fire measurement of fire severity and intensity in the Christmas 2001 table ASydney wildfires. Int. J. Wildl. Fire 2004, 13, 227–240. [Google Scholar] [CrossRef]
  168. Lecina-Diaz, J.; Alvarez, A.; Retana, J. Extreme fire severity patterns in topographic, convective and wind-driven historical wildfires of mediterranean pine forests. PLoS ONE 2014, 9. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  169. Pollet, J.; Omi, P.N. Effect of thinning and prescribed burning on crown fire severity in ponderosa pine forests. Int. J. Wildl. Fire 2002, 11, 1–10. [Google Scholar] [CrossRef]
  170. Parks, S.A.; Miller, C.; Abatzoglou, J.T.; Holsinger, L.M.; Parisien, M.-A.; Dobrowski, S.Z. How will climate change affect wildland fire severity in the western US? Environ. Res. Lett. 2016, 11, 35002. [Google Scholar] [CrossRef]
  171. Miller, J.D.; Thode, A.E. Quantifying burn severity in a heterogeneous landscape with a relative version of the delta Normalized Burn Ratio (dNBR). Remote Sens. Environ. 2007, 109, 66–80. [Google Scholar] [CrossRef]
  172. Morrow, B.; Davies, J.; Johnston, K. Wildland Urban Interface Wildfire Threat Assessments in B.C.; Ministry of Forests, Lands and Natural Resource Operations Wildfire Management Branch: British Columbia, Canada, 2013.
  173. Moritz, M.A. Analyzing Extreme Disturbance Events: Fire in Los Padres National Forest. Ecol. Appl. 1997, 7, 1252–1262. [Google Scholar] [CrossRef]
  174. Platt, W.J.; Orzell, S.L.; Slocum, M.G. Seasonality of Fire Weather Strongly Influences Fire Regimes in South Florida Savanna-Grassland Landscapes. PLoS ONE 2015, 10, e0116952. [Google Scholar] [CrossRef] [PubMed]
Figure 1. Demonstration of how ecological and social processes, conditions, and factors interplay throughout the wildfire temporal phases. A more detailed list of processes, conditions and factors is reported in Table A1.
Figure 1. Demonstration of how ecological and social processes, conditions, and factors interplay throughout the wildfire temporal phases. A more detailed list of processes, conditions and factors is reported in Table A1.
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Figure 2. EWEs and wildfire disasters as social constructs. The left rectangle shows a three-ways interaction: between physical components (e.g., weather) and fire; between people/society and fire (e.g., ignition); and between people /society and the physical components (e.g., land management, fuel reduction, silviculture, creation of roads, water points). The right rectangle represents a two-way relationship between fire and all the components of human system (e.g., individuals, communities, organizations, properties rights, legislation, planning, preparedness, mitigation, resources, culture) because EWEs are a threat to people and assets but people can attenuate the threat reducing the vulnerability and increasing the resilience. The word society synthesizes the plurality of processes, conditions and factors that interplay with fires in different cultural and geographical contexts.
Figure 2. EWEs and wildfire disasters as social constructs. The left rectangle shows a three-ways interaction: between physical components (e.g., weather) and fire; between people/society and fire (e.g., ignition); and between people /society and the physical components (e.g., land management, fuel reduction, silviculture, creation of roads, water points). The right rectangle represents a two-way relationship between fire and all the components of human system (e.g., individuals, communities, organizations, properties rights, legislation, planning, preparedness, mitigation, resources, culture) because EWEs are a threat to people and assets but people can attenuate the threat reducing the vulnerability and increasing the resilience. The word society synthesizes the plurality of processes, conditions and factors that interplay with fires in different cultural and geographical contexts.
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Table 1. Comparative analysis of EWE definition criteria.
Table 1. Comparative analysis of EWE definition criteria.
Definition
Criteria
MetricsBowman et al.
(2017) [1]
Lannom et al.
(2014) [56]
McRae
(2010) [20]
McRae and Sharples
(2011) [21]
Oliveri et al.
(2012) [69]
Sampson et al.
(2000) [54]
Weber and Dold
(2006) [68]
Post-Fire
Metric
Size + ++
Duration +
ImpactsProportion of area burnt with high severity +
Impacts+
Fire
Environment
Fuel load and structure +
Wind speed + +
Wind direction change +
Atmospheric instability * + +
Distance to the wildland–urban interface +
Fire
Behavior
Extreme phenomena ** ++
Fire radiative power +
Rapid evolution +
Note: * As described by the Haines Index; ** Including eruptive fire behavior, vorticity-driven lateral spread, mass spotting.
Table 2. Criteria for the definition of EWE and their social implications and outcomes.
Table 2. Criteria for the definition of EWE and their social implications and outcomes.
CriteriaIndicatorsSocial Implications and Outcomes
Fire behaviorFLI ≥10,000 kWm-1DURING FIRE SPREAD AND SUPPRESSION
Increase of the area of intervention:
(i) Requires more fire suppression resources;
(ii) Increases the threatened area and potential losses and damages.
Response capacity of suppression crews:
(i) Reorganization of suppression activities is made difficult by the increasing ROS;
(ii) Deployed crews are rapidly overwhelmed.
Capacity of reaction of people and displacement capacity is overwhelmed by ROS and massive spotting.
Impacts:
(i) Smoke problems: increased hospital admissions during and immediately after the fires; poor visibility; impacts on displacement and on the use of firefighting aircraft;
(ii) Loss of lives.
AFTER SUPPRESSION
Short -term and long-term impacts:
(i) Loss of lives and injured people;
(ii) Economic damages;
(iii) High severity.
Plume dominated event with EFBPossible pyroCb with downdrafts
FL≥ 10 m
ROS ≥ 50 m/min
SpottingActivity
Distance
Fire behavior sudden changes Unpredictable variations of fire intensity
Erratic ROS direction
Spotting
Capacity of controlDifficulty of control Fire behavior overwhelms capacity of control
Fire spreads unchecked, as suppression operations are either not attempted or ineffective
DURING SUPPRESSION Immediate consequences:
(i) Entrapments and fire overruns;
(ii) Unplanned last moment evacuations;
(iii) Entrapments with multiple fatalities and near misses;
(iv) Fatal fire overruns.
Note: The criteria to define EWE are only contained in the first and second column. The integration in the table of social implications and outcomes (fourth column) has the purpose to show the interplay of fire behavior and capacity of control with several social issues. The implications and outcomes are not exhaustively listed and they are not exclusive and specific for EWEs but certainly they can be magnified in case of EWEs occurrence.
Table 3. Wildfire events classification based on fire behavior and capacity of control.
Table 3. Wildfire events classification based on fire behavior and capacity of control.
Fire CategoryReal Time Measurable Behavior ParametersReal Time Observable Manifestations of EFBType of Fire and Capacity of Control *
FLI* (kWm−1)ROS (m/min)FL (m)PyroCbDowndraftsSpotting ActivitySpotting Distance (m)
Normal Fires1<500<5
<15 b
<1.5AbsentAbsentAbsent0Surface fire
Fairly easy
2500–2000<15
<30 b
<2.5AbsentAbsentLow<100Surface fire
Moderately difficult
32000–4000<20 c
<50 d
2.5-3.5AbsentAbsentHigh≥100Surface fire, torching possible
Very difficult
44000–10,000<50 c
<100 d
3.5-10UnlikelyIn some localized casesProlific500–1000Surface fire, crowning likely depending on vegetation type and stand structure
Extremely difficult
Extreme Wildfire Events510,000–30,000<150 c
<250 d
10-50PossiblePresentProlific>1000Crown fire, either wind- or plume-driven
Spotting plays a relevant role in fire growth
Possible fire breaching across an extended obstacle to local spread
Chaotic and unpredictable fire spread
Virtually impossible
630,000–100,000<30050-100ProbablePresentMassive Spotting>2000Plume-driven, highly turbulent fire
Chaotic and unpredictable fire spread
Spotting, including long distance, plays a relevant role in fire growth
Possible fire breaching across an extended obstacle to local spread
Impossible
7>100,000 (possible)>300 (possible)>100 (possible)PresentPresentMassive Spotting>5000Plume-driven, highly turbulent fire
Area-wide ignition and firestorm development non-organized flame fronts because of extreme turbulence/vorticity and massive spotting
Impossible
Note: a Forest and shrubland; b grassland; c forest; d shrubland and grassland; *FLI classes 1–4 follow the classification by Alexander and Lanoville [125].

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Tedim, F.; Leone, V.; Amraoui, M.; Bouillon, C.; Coughlan, M.R.; Delogu, G.M.; Fernandes, P.M.; Ferreira, C.; McCaffrey, S.; McGee, T.K.; et al. Defining Extreme Wildfire Events: Difficulties, Challenges, and Impacts. Fire 2018, 1, 9. https://doi.org/10.3390/fire1010009

AMA Style

Tedim F, Leone V, Amraoui M, Bouillon C, Coughlan MR, Delogu GM, Fernandes PM, Ferreira C, McCaffrey S, McGee TK, et al. Defining Extreme Wildfire Events: Difficulties, Challenges, and Impacts. Fire. 2018; 1(1):9. https://doi.org/10.3390/fire1010009

Chicago/Turabian Style

Tedim, Fantina, Vittorio Leone, Malik Amraoui, Christophe Bouillon, Michael R. Coughlan, Giuseppe M. Delogu, Paulo M. Fernandes, Carmen Ferreira, Sarah McCaffrey, Tara K. McGee, and et al. 2018. "Defining Extreme Wildfire Events: Difficulties, Challenges, and Impacts" Fire 1, no. 1: 9. https://doi.org/10.3390/fire1010009

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