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For other uses, see Wildfire (disambiguation).
A daytime fire engulfing large trees
A wildfire on September 5, 2008 in California, USA

A wildfire is any uncontrolled fire that occurs in the countryside or a wilderness area.[1][2] Reflecting the type of vegetation or fuel, other names such as brush fire, bushfire, forest fire, grass fire, hill fire, peat fire, vegetation fire, and wildland fire may be used to describe the same phenomenon. A wildfire differs from other fires by its extensive size, the speed at which it can spread out from its original source, and its ability to change direction unexpectedly and to jump gaps, such as roads, rivers and fire breaks.[3] Wildfires are characterized in terms of the cause of ignition, their physical properties such as speed of propagation; the combustible material present; and the effect of weather on the fire.[4]

Wildfires occur on every continent except Antarctica. Fossil records and human history contain accounts of wildfires, which can be cyclical events.[5][6] Wildfires can cause extensive damage, both to property and human life, but they also have various beneficial effects on wilderness areas. Some plant species depend on the effects of fire for growth and reproduction,[5] although large wildfires may also have negative ecological effects.[4]

Strategies of wildfire prevention, detection, and suppression have varied over the years, and international wildfire management experts encourage further development of technology and research.[7] Current techniques may permit and even encourage smaller fires in some regions to minimize or remove sources of flammable material from any wildfire that might develop.[8][9] While some wildfires burn in remote forested regions, they can cause extensive destruction of homes and other property located in the wildland-urban interface: a zone of transition between developed areas and undeveloped wilderness.[8][10]

Characteristics

Africa with red and yellow markers where fires have been detected. A wide red band of markers runs east-west, just south of the Sahara Desert.
The distribution of wildfires on the African continent during the year 2002.

The name wildfire was once a synonym for Greek fire but now refers to any furious or destructive conflagration.[2] Wildfires differ from other fires in that they take place outdoors in areas of grassland, woodlands, bushland, scrubland, peatland, and other woody materials that act as a source of fuel, or combustible material. Buildings may become involved if a wildfire spreads to adjacent communities and threatens these structures. While the causes of wildfires vary and the outcomes are always unique, all wildfires can be characterized in terms of their physical properties, their fuel type, and the effect that weather has on the fire.

Wildfire behavior and severity result from the combination of factors such as available fuels, physical setting, and weather.[11] These factors include fuel type, moisture content in the fuel, humidity, wind speed, topography, geographic location, and ambient temperature.[12][13][14] While wildfires may be categorized as large, uncontrolled disasters that burn through 0.4 to 400 square kilometres (100 to 100,000 acres)* or more, they can be as small as 0.0010 square kilometers (0.25 acres) or less.[15][16][17] However, even though smaller events may be included in wildfire modeling, most do not earn press attention. This can be problematic because public fire policies are influenced more by the way the media portrays catastrophic wildfires than by small fires.[18][19][20]

Causes

The four major natural causes of wildfire ignitions are lightning, volcanic eruption, sparks from rockfalls, and spontaneous combustion.[21] The thousands of coal seam fires that are burning around the world can also flare up and ignite nearby flammable material such as those in Centralia, Pennsylvania, Burning Mountain, Australia, and several coal-sustained fires in China.[22][23] However, many wildfires are attributed to human sources such as arson, discarded cigarettes, sparks from equipment, and power line arcs (as detected by arc mapping).[24][25] In societies experiencing shifting cultivation where land is cleared quickly and farmed until the soil loses fertility, slash and burn clearing is often considered the least expensive way to prepare land for future use.[26][27] Forested areas cleared by logging encourage the dominance of flammable grasses, and abandoned logging roads overgrown by vegetation may act as fire corridors. Annual grassland fires in Southern Vietnam can be attributed in part to the destruction of forested areas by herbicides, explosives, and mechanical land clearing and burning operations during the Vietnam War.[28]

Physical properties

See also: Combustion, Fire, Fire control, Extreme weather, and Firestorm

Wildfires occur when the necessary elements of a fire triangle intersect: an ignition source is brought into contact with a combustible material such as vegetation, that is subjected to sufficient heat and has an adequate supply of oxygen from the ambient air. A high moisture content usually prevents ignition and slows propagation, because higher temperatures are required to evaporate any water within the material and heat the material to its fire point.[3][14] Dense forests usually provide more shade, resulting in lower ambient temperatures and greater humidity.[12] Less dense material such as grasses and leaves are easier to ignite because they contain less water than denser material such as branches and trunks.[29] Plants continuously lose water by evapotranspiration, but water loss is usually balanced by water absorbed from the soil, humidity, or rain.[30] When this balance is not maintained, plants dry out and are therefore more flammable, often a consequence of long, hot, dry periods.[31][32]

A line of trees completely engulfed in flames. Towers with instrumentation are seen just beyond the fire's reach.
Experimental fire in Canada

A wildfire front is the portion sustaining continuous flaming combustion, where unburned material meets active flames, or the smoldering transition between unburned and burned material.[33] As the front approaches, the fire heats both the surrounding air and woody material through convection and thermal radiation. First, wood is dried as water is vaporized at a temperature of 100 °C (212 °F). Next, the pyrolysis of wood at 230 °C (450 °F) releases flammable gases. Finally, wood can smolder at 380 °C (720 °F) or, when heated sufficiently, ignite at 590 °C (1,000 °F).[34][35] Even before the flames of a wildfire arrive at a particular location, heat transfer from the wildfire front can precede the flames, warming the air to 800 °C (1,470 °F) and drying and pre-heating flammable materials.[29][36] High-temperature and long-duration surface wildfires may encourage flashover or torching: the drying of tree canopies and their subsequent ignition from below.[37]

Wildfires can advance tangential to the main front to form a flanking front, or burn opposite the direction of the main front by backing.[38] They may also spread by jumping or spotting as winds and vertical convection columns carry firebrands (hot wood embers) and other burning materials through the air over roads, rivers, and other barriers that may otherwise act as firebreaks.[39][40] Torching and fires in tree canopies encourage spotting, and dry ground fuels that surround a wildfire are especially vulnerable to ignition from firebrands.[41] In Australian bushfires, spot fires have been documented 10 kilometers (6 mi) from the fire front.[42]

Wildfires have a rapid forward rate of spread (FROS) when fueled by dense uninterrupted vegetation, particularly in wooded areas with canopies.[43] They can move as fast as 10.8 kilometers per hour (6.7 mph) in forests and 22 kilometers per hour (14 mph) in grasslands.[44] A wildfire's burning front may also change direction unexpectedly and jump across fire breaks. Intense heat and smoke can lead to disorientation and loss of appreciation of the direction of the fire. These factors make fires particularly dangerous: in the 1949 Mann Gulch fire in Montana, USA, thirteen smokejumpers died when they lost their communication links and became disorientated; the fire consumed 18 square kilometers (4,400 acres).[45] In the Australian February 2009 Victorian bushfires, at least 173 people died and over 2,029 homes and 3,500 structures were lost when they became engulfed by wildfire.[46]

Especially large wildfires may affect air currents in their immediate vicinities by acting as natural chimneys. In an occurrence termed stack effect, air rises as it is heated, and large wildfires create powerful updrafts that will draw in new, cooler air from surrounding areas in thermal columns.[47] Great vertical differences in temperature and humidity encourage pyrocumulus clouds, strong winds, and fire whirls with the force of tornadoes at speeds of more than 80 kilometers per hour (50 mph).[48][49][50] Wide rates of spread, prolific crowning and/or spotting, the presence of fire whirls, and strong convection columns signify extreme conditions.[51]

Fuel type

Flat expanse of brown grasses and some green trees with black and some gray smoke and visible flames in the distance.
A surface fire in the western desert of Utah, U.S.
Mountainous region with blackened soil and trees due to a recent fire.
Charred landscape following a crown fire in the North Cascades, U.S.

The spread of wildfires varies based on the flammable material present and its vertical arrangement.[52] Fuel density is governed by topography, as land shape determines factors such as available sunlight and water for plant growth. For example, fuels uphill from a fire are more readily dried and warmed by the fire than those downhill, yet burning logs can roll downhill. Overall, fire types can be generally characterized by their fuel:[note 1]

  • Ground fires are fed by subterranean roots, duff and other buried organic matter. This fuel type is especially susceptible to ignition due to spotting. Ground fires typically burn by smoldering, and can burn slowly for days to months, such as peat fires in Kalimantan and Eastern Sumatra, Indonesia, which resulted from a riceland creation project that unintentionally drained and dried the peat.[53][54]
  • Crawling or surface fires are fueled by low-lying vegetation such as leaf and timber litter, debris, grass, and low-lying shrubbery.[55] Human-ignited ground-clearing fires can spread to the Amazon rain forest, damaging ecosystems not particularly suited for heat or arid conditions.[56]
  • Ladder fires consume material between low-level vegetation and tree canopies, such as small trees, downed logs, and vines. Invasive plants such as Kudzu and Old World climbing fern that scale trees may also encourage ladder fires.[57]
  • Crown, canopy, or aerial fires burn suspended material at the canopy level, such as tall trees, vines, and mosses. The ignition of a crown fire is dependent on the density of the suspended material, canopy height, canopy continuity, and sufficient surface and ladder fires in order to reach the tree crowns.[58]

Effect of weather

Heat waves, droughts, cyclical climate changes such as El Niño, and regional weather patterns such as high-pressure ridges can increase the risk and alter the behavior of wildfires dramatically.[59][60] Years of precipitation followed by warm periods have encouraged more widespread fires and longer fire seasons.[61] Since the mid 1980s, earlier snowmelt and associated warming has also been associated with an increase in length and severity of the wildfire season in the Western United States.[62] However, one individual element does not always cause an increase in wildfire activity. For example, wildfires will not occur during a drought unless accompanied by other factors, such as lightning (ignition source) and strong winds (mechanism for rapid spread).[63]

Fire intensity also increases during daytime hours. Burn rates of smoldering logs are up to five times greater during the day due to lower humidity, increased temperatures, and increased wind speeds.[64] Sunlight warms the ground during the day which creates air currents that travel uphill. At night the land cools, creating air currents that travel downhill. Wildfires are fanned by these winds and often follow the air currents over hills and through valleys.[65] Fires in Europe occur frequently during the hours of 12:00 p.m. and 2:00 p.m.[66] U.S. wildfire operations revolve around a 24-hour fire day that begins at 1000 hours due to the predictable increase in intensity resulting from the daytime warmth.[67]

Ecology

Main article: Fire ecology
See also: Disturbance (ecology) and Forestry
Two illustrations of the earth, one above the other. The seas are dark gray in color and the continents a lighter gray. Both images have red, yellow, and white markers indicating where fires occurred during the months of August (top image) and Februrary (bottom image) of the year 2008.
Global fires during the year 2008 for the months of August (top image) and February (bottom image), as detected by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite.

Wildfires are common in climates that are sufficiently moist to allow the growth of vegetation but feature extended dry, hot periods.[5] Such places include the vegetated areas of Australia and Southeast Asia, the veld in the interior and the fynbos in the Western Cape of South Africa, the forested areas of the United States and Canada, and in the Mediterranean Basin. Fires can be particularly intense during days of strong winds, periods of drought, and during warm summer months.[68][69] Global warming may increase the intensity and frequency of droughts in many areas, creating more intense and frequent wildfires.[4][70][71]

Many ecosystems suffer from too much fire, such as the chaparral in southern California and lower elevation deserts in the American Southwest. While these areas are considered fire-dependent, the increased fire frequency has upset natural cycles, destroyed native plant communities, and encouraged the growth of fire-intolerant vegetation and non-native weeds.[72][73][74][75] Invasive species such as Lygodium microphyllum and Bromus tectorum may create a positive feedback loop, increasing fire frequency even more.[57][76] In the Amazon Rainforest, drought, logging and cattle ranching practices, and slash-and burn agriculture damage fire-resistant forests and promote the growth of flammable brush, creating a cycle that encourages more burning.[77] Fires in the rainforest threaten its collection of diverse species, produce large amounts of CO2, and threaten to "clear or severely damage 55 per cent of the Amazon rainforest by the year 2030" according to Rebecca Lindsay of NASA's Earth Observatory.[78][79] Wildfires generate ash, destroy available organic nutrients, and cause an increase in water runoff, eroding away other nutrients and creating flash flood conditions.[52][80] A 2003 wildfire in the North Yorkshire Moors destroyed some 2.5 square kilometers (600 acres) of heather and the underlying peat layers. Afterwards, wind erosion stripped the ash and the exposed soil, revealing archaeological remains dating back to 10,000 BC.[81] Wildfires can also have an effect on climate change, increasing the amount of carbon released into the atmosphere and inhibiting vegetation growth, which affects overall carbon uptake by plants.[82]

Plant adaptations

Template:Details3

Two photographs of the same section of a pine forest; both show blackened bark at least halfway up the trees. The first picture is noticeably lacking in surface vegetation, while the second shows small, green grasses on the forest floor.
Ecological succession after a wildfire in a boreal pine forest next to Hara Bog, Lahemaa National Park, Estonia. The pictures were taken one and two years after the fire.

Organisms in wildfire-prone ecosystems often survive through adaptations to their local fire regime. Such adaptations include physical protection against heat, increased growth after a fire event, and flammable materials that encourage fire and may eliminate competition. Dense bark, shedding lower branches, and high water content in external structures may protect the organisms from rising temperatures.[5] Fire-resistant seeds and reserve shoots that sprout after a fire encourage species preservation, as embodied by pioneer species. Smoke, charred wood, and heat are common fire cues that stimulate the germination of seeds in a process called serotiny.[83] Exposure to smoke from burning plants promotes germination in other types of plants by inducing the production of the orange butenolide.[84]

Grasslands in Western Sabah, Malaysian pine forests, and Indonesian Casuarina forests are believed to have resulted from previous periods of fire.[85] Plants of the genus Eucalyptus contain flammable oils that encourage fire and hard sclerophyll leaves to resist heat and drought, ensuring their dominance over less fire-tolerant species.[86][87] Chamise deadwood litter is low in water content and flammable, and the shrub quickly sprouts after a fire.[5] Sequoia rely on periodic fires to reduce competition, release seeds from their cones, and clear the soil and canopy for new growth.[88] Caribbean Pine in Bahamian pineyards have adapted to and rely on low-intensity, surface fires for survival and growth. An optimum fire frequency for growth is every 3 to 10 years. Too frequent fires favor herbaceous plants, and infrequent fires favor species typical of Bahamian dry forests.[89]

Atmospheric effects

See also: Air pollution, Atmospheric chemistry, Haze, 1997 Southeast Asian haze, 2005 Malaysian haze, and 2006 Southeast Asian haze
A paved road with trees and grasses on the side with a large, white and dark gray smoke could rising in the distance.
A Pyrocumulus cloud produced by a wildfire in Yellowstone National Park

Most of the Earth's weather and air pollution reside in the troposphere, the part of the atmosphere that extends from the surface of the planet to a height of between 8 and 13 kilometers (5 and 8 mi). A severe thunderstorm or pyrocumulonimbus in the area of a large wildfire can have its vertical lift enhanced to boost smoke, soot and other particulate matter as high as the lower stratosphere.[90] Previously, prevailing scientific theory held that most particles in the stratosphere came from volcanoes, but smoke and other wildfire emissions have been detected from the lower stratosphere.[91] Pyrocumulus clouds can reach 6,100 meters (20,000 ft) over wildfires.[92] With an increase in fire byproducts in the stratosphere, ozone concentration was three times more likely to exceed health standards.[93] Satellite observation of smoke plumes from wildfires revealed that the plumes could be traced intact for distances exceeding 1,600 kilometers (1,000 mi).[94] Computer-aided models such as CALPUFF may help predict the size and direction of wildfire-generated smoke plumes by using atmospheric dispersion modeling.[95]

Wildfires can affect climate and weather and have major impacts on regional and global pollution.[96] Wildfire emissions contain greenhouse gases and a number of criteria pollutants which can have a substantial impact on human health and welfare.[97] Forest fires in Indonesia in 1997 were estimated to have released between 0.81 and 2.57 gigatonnes (0.89 and 2.83 billion short tones) of CO2 into the atmosphere, which is between 13%–40% of the annual carbon dioxide emissions from burning fossil fuels.[98][99] Atmospheric models suggest that these concentrations of sooty particles could increase absorption of incoming solar radiation during winter months by as much as 15%.[100]

Panorama of a hilly expanse featuring a large smoke trail covering more than half of the visible sky.
Smoke trail from a fire seen while looking towards Dargo from Swifts Creek, Victoria, Australia, 11 January 2007

History

Template:Origin of fire

Human involvement

See also: Control of fire by early humans, Deforestation § Historical causes, Environmental history, History of firefighting, and List of wildfires

Wildfires have been mentioned in human history, including minor allusions in the Bible and classical writers such as Homer. However, while ancient Hebrew, Greek, and Roman writers were aware of fires, they were not very interested in the uncultivated lands where wildfires occurred.[101][102] Wildfires were used in battles throughout human history as early thermal weapons. From the Middle ages, accounts were written of occupational burning as well as customs and laws that governed the use of fire. In 14th century Sardinia, firebreaks were used for wildfire protection. In Spain during the 1550s, sheep husbandry was discouraged in certain provinces by Phillip II due to the harmful effects of fires used in transhumance.[101][102] In the countries bordering the Baltic Sea, fire in land use systems was typical during the Neolithic period until World War II.[103] As early as the 1600s, Native Americans were observed using fire for many purposes including cultivation, signaling, and warfare. Scottish botanist David Douglas noted the native use of fire for tobacco cultivation, to encourage deer into smaller areas for hunting purposes, and to improve foraging for honey and grasshoppers. Charcoal found in sedimentary deposits off the Pacific coast of Central America suggests that more burning occurred in the 50 years before the Spanish colonization of the Americas than after the colonization.[104]

Wildfires typically occurred during periods of increased temperature and drought. An increase in fire-related debris flow in alluvial fans of northeastern Yellowstone National Park was linked to the period between AD 1050 and 1200, coinciding with the Medieval Warm Period.[105] However, human influence caused an increase in fire frequency. Dendrochronological fire scar data and charcoal layer data in Finland suggests that, while many fires occurred during severe drought conditions, an increase in the number of fires during 850 BC and 1660 AD can be attributed to human influence.[106] Charcoal evidence from the Americas suggested a general decrease in wildfires between 1 AD and 1750 compared to previous years. However, a period of increased fire frequency between 1750 and 1870 was suggested by charcoal data from North America and Asia, attributed to human population growth and influences such as land clearing practices. This period was followed by an overall decrease in burning in the 20th century, linked to the expansion of agriculture, increased livestock grazing, and fire prevention efforts.[107]

Prevention

See also: Fire protection
Drawing of a grizzly bear with human features. He is wearing blue jeans with a belt and a brimmed hat with the name "Smokey" on the cap, and has a shovel in his left hand. He is pointing to the viewer while the text "Only You" is seen below him.
1985 Smokey Bear poster with part of his admonition, "Only you can prevent forest fires".

Wildfire prevention refers to the preemptive methods of reducing the risk of fires as well as lessening its severity and spread.[108] Effective prevention techniques allow supervising agencies to manage air quality, maintain ecological balances, protect resources,[76] and to limit the effects of future uncontrolled fires.[109] North American firefighting policies may permit naturally-caused fires to burn to maintain their ecological role, so long as the risks of escape onto high-value areas are mitigated.[110] However, prevention policies must consider the role that humans play in wildfires, since, for example, only 5% of forest fires in Europe are not related to human involvement.[111] Sources of human-caused fire may include arson, accidental ignition, or the uncontrolled use of fire in land-clearing and agriculture such as the slash-and-burn farming in Southeast Asia.[112] Landholders with flammable investments such as orchards and tree crops may encourage neighboring landowners to reduce fire risks.[113]

In the mid-1800s, explorers from the HMS Beagle observed Australian Aborigines using fire for ground clearing, hunting, and regeneration of plant food in a method called fire-stick farming.[114] Such careful use of fire has been employed for centuries in the lands protected by Kakadu National Park to encourage biodiversity.[115] In 1937, U.S. President Franklin D. Roosevelt initiated a nationwide fire prevention campaign, highlighting the role of human carelessness in forest fires. Later posters of the program featured Uncle Sam, leaders of the Axis powers of World War II, characters from the Disney movie Bambi, and the official mascot of the U.S. Forest Service, Smokey Bear.[116]

A small fire on the slope of a hill. The hill features small, green shubbery and some trees. A person in light-colored clothing in seen in the background, some distance from the flames.
A prescribed burn in a Pinus nigra stand in Portugal

Wildfires are caused by a combination of factors such as topography, fuels, and weather. Other than reducing human infractions, only fuels may be altered to affect future fire risk and behavior.[52] Wildfire prevention programs around the world may employ techniques such as wildland fire use and prescribed or controlled burns.[1][117][118] Wildland fire use refers to any fire of natural causes that is monitored but allowed to burn. Controlled burns are fires ignited by government agencies under less dangerous weather conditions.[119] Vegetation may be burned periodically to maintain high species diversity, and frequent burning of surface fuels limits fuel accumulation, thereby reducing the risk of crown fires.[120][121] Using strategic cuts of trees, fuels may also be removed by handcrews in order to clean and clear the forest, prevent fuel build-up, and create access into forested areas.[122] Chain saws and large equipment can be used to thin out ladder fuels and shred trees and vegetation to a mulch.[123] Multiple fuel treatments are often needed to influence future fire risks, and wildfire models may be used to predict and compare the benefits of different fuel treatments on future wildfire spread.[52] However, controlled burns are reportedly "the most effective treatment for reducing a fire’s rate of spread, fireline intensity, flame length, and heat per unit of area" according to Jan Van Wagtendonk, a biologist at the Yellowstone Field Station.[124] Additionally, while fuel treatments are typically limited to smaller areas, effective fire management requires the administration of fuels across large landscapes in order to reduce future fire size and severity.[125]

Building codes in fire-prone areas typically require that structures be built of flame-resistant materials and a defensible space be maintained by clearing flammable materials within a prescribed distance from the edifice.[126][127] Communities in the Philippines also maintain fire lines 5 to 10 meters (16 to 33 ft) wide between the forest and their village, and patrol these lines during summer months or seasons of dry weather.[128]

Three photos of the same forest region. The first features a central tree with other trees in the distance. A man and two mounted horses are seen at varying distances behind the central tree. The forest floor features low-lying vegetation such as grasses. The second and third photos feature the same central tree but with increasing amounts of trees in the mid- and foregrounds. The central tree is almost completely blocked from view in the third picture.
A ponderosa pine stand in the Bitterroot National Forest in Montana in 1909, 1948, and 1989. The increase in vegetation density was attributed to fire prevention efforts since 1895.[129]

Detection

See also: Remote sensing
A four-legged tower with a small enclosure at the top, next to two one-story buildings. The tower is four stories tall. Trees are at either side, and in the foreground there are rocks, some vegetation, and a rough trail.
Dry Mountain Fire Lookout in the Ochoco National Forest, Oregon, circa 1930

Fast and effective detection is a key factor in wildfire fighting.[130] Early detection efforts were focused on early response, accurate day and nighttime use, the ability to prioritize fire danger, and fire size and location in relation to topography.[131] Fire lookout towers were used in the United States in the early 1900s and fires were reported using telephones, carrier pigeons, and heliographs.[132] Aerial and land photography using instant cameras were used in the 1950s until infrared scanning was developed for fire detection in the 1960s. However, information analysis and delivery was often delayed by limitations in communication technology. Early satellite-derived fire analyses were hand-drawn on maps at a remote site and sent via overnight mail to the fire manager. During the Yellowstone fires of 1988, a data station was established in West Yellowstone, permitting fire information delivery in approximately four hours.[131]

Currently, public hotlines, fire lookouts in towers, and ground and aerial patrols can be used as a means of early detection of forest fires. However, accurate human observation may be limited by operator fatigue, time of day, time of year, and geographic location. Electronic systems have gained popularity in recent years as a possible resolution to human operator error. These systems may be semi- or fully-automated and employ systems based on the risk area and degree of human presence, as suggested by GIS data analyses. An integrated approach of multiple systems can be used to merge satellite data, aerial imagery, and personnel position via Global Positioning System (GPS) into a collective whole for near-realtime use by wireless Incident Command Centers.[133][134]

A small, high risk area that features thick vegetation, a strong human presence, or is close to a critical urban area can be monitored using a local sensor network. Detection systems may include wireless sensor networks that act as automated weather systems: detecting temperature, humidity, and smoke.[135][136][137] These may be battery-powered, solar-powered, or tree-rechargeable: able to recharge their battery systems using the small electrical currents in plant material.[138] Larger, medium-risk areas can be monitored by scanning towers that incorporate fixed cameras and sensors to detect smoke or additional factors such as the infrared signature of carbon dioxide produced by fires. Brightness and color change detection and night vision capabilities may be incorporated also into sensor arrays.[139][140][141]

A satellite view of the Balkans and Greece. Clouds and smoke trails are seen above the Balkans and trailing south into the Ionian Sea.
Wildfires across the Balkans in late July 2007 (MODIS image)

Satellite and aerial monitoring can provide a wider view and may be sufficient to monitor very large, low risk areas. These more sophisticated systems employ GPS and aircraft-mounted infrared or high-resolution visible cameras to identify and target wildfires.[142][143] Satellite-mounted sensors such as Envisat's Advanced Along Track Scanning Radiometer and European Remote-Sensing Satellite's Along-Track Scanning Radiometer can measure infrared radiation emitted by fires, identifying hot spots greater than 39 °C (102 °F).[144][145] The National Oceanic and Atmospheric Administration's Hazard Mapping System combines remote-sensing data from satellite sources such as Geostationary Operational Environmental Satellite (GOES), Moderate-Resolution Imaging Spectroradiometer (MODIS), and Advanced Very High Resolution Radiometer (AVHRR) for detection of fire and smoke plume locations.[146][147] However, satellite detection is prone to offset errors, anywhere from 2 to 3 kilometers (1 to 2 mi) for MODIS and AVHRR data and up to 12 kilometers (7.5 mi) for GOES data.[148] Satellites in geostationary orbits may become disabled, and satellites in polar orbits are often limited by their short window of observation time. Cloud cover and image resolution and may also limit the effectiveness of satellite imagery.[149]

Suppression

Main article: Wildfire suppression
See also: Firefighting
A three-engine red-and-white cargo plane in-flight, releasing a large quantity of water from its undercarriage storage tanks. The water trails behind the aircraft in a continuous, fan-shaped drop pattern.
Tanker 910 during a drop demonstration in December, 2006

Wildfire suppression may include a variety of tools and technologies, including throwing sand and beating fires with sticks and palm fronds in rural Thailand, using silver iodide to encourage snow fall in China, and full-scale aerial assaults by ALTUS II unmanned aerial vehicles, planes, and helicopters using drops of water and fire retardants.[150][151][152][153] Complete fire suppression is no longer an expectation, but the majority of wildfires are often extinguished before they grow out of control. While more than 99% of the 10,000 new wildfires each year are contained, escaped wildfires can cause extensive damage. Worldwide damage from wildfires is in the billions of euros annually.[154] Wildfires in Canada and the US consume an average of 54,500 square kilometers (13,000,000 acres) per year.[155][156]

Fuel buildup can result in costly, devastating fires as new homes, ranches, and other development are built adjacent to wilderness areas. Continued growth in fire-prone areas and rebuilding structures destroyed by fires has been met with criticism.[157] However, the population growth along the wildland-urban interface discourages the use of current fuel management techniques. Smoke is an irritant and attempts to thin out the fuel load is met with opposition due to desirability of forested areas, in addition to other wilderness goals such as endangered species protection and habitat preservation.[158] The ecological benefits of fire is often overridden by the economic benefits of protecting structures and lives.[159] For example, while fuel treatments decrease the risk of crown fires, these techniques destroy the habitats of various plant and animal species.[160] Additionally, government policies that cover the wilderness usually differs from local and state policies that govern urban lands.[161][162]

Modeling

Main article: Wildfire modeling
A dark region shaped like a shield with a pointed bottom. An arrow and the text "propagation axis (wind)" indicates a bottom-to-top direction up the body of the shield shape. The shape's pointed bottom is labeled "fire start". Around the shield shape's top and thinning towards its sides, a yellow-orange region is labeled "left front", "right front", and (at the top) "head of the fire".
Fire Propagation Model

Wildfire modeling is concerned with numerical simulation of wildfires in order to understand and predict fire behavior.[163][164] Wildfire modeling can ultimately aid wildfire suppression, namely increase the safety of firefighters and the public, reduce risk, and minimize damage. Using computational science, wildfire modeling involves the statistical analysis of past fire events to predict spotting risks and front behavior. Various wildfire propagation models have been proposed in the past, including simple ellipses and egg- and fan-shaped models. Early attempts to determine wildfire behavior assumed terrain and vegetation uniformity. However, the exact behavior of a wildfire's front is dependent on a variety of factors, including windspeed and slope steepness. Modern growth models utilize a combination of past ellipsoidal descriptions and Huygens' Principle to simulate fire growth as a continuously expanding polygon.[165][166] Extreme value theory may also be used to predict the size of large wildfires. However, large fires that exceed suppression capabilities are often regarded as statistical outliers in standard analyses, even though fire policies are more influenced by catastrophic wildfires than by small fires.[18]

See also

2

Notes

  1. ^ This section is a composite of several references. Refer to:

References

  1. ^ a b Federal Fire and Aviation Operations Action Plan, 4.
  2. ^ a b Cambridge Advanced Learner's Dictionary, Third Edition. Cambridge University Press; 2008. ISBN 9780521858045.
  3. ^ a b National Interagency Fire Center. The Science of Wildland fire [Retrieved 2008-11-21].
  4. ^ a b c Forest Fires and Climate Change in the 21st century [PDF]. Mitigation and Adaptation Strategies for Global Change. 2005 [Retrieved 2009-06-26];11:847. doi:10.1007/s11027-005-9020-7.
  5. ^ a b c d e Stephen J. Pyne. NOVA online. How Plants Use Fire (And Are Used By It) [Retrieved 2009-06-30].
  6. ^ NOVA online - Public Broadcasting System (PBS). The World on Fire; June 2002 [Retrieved 2009-07-13].
  7. ^ Voice of America (VOA) News. International Experts Study Ways to Fight Wildfires; 2009-06-24 [Retrieved 2009-07-09].
  8. ^ a b Interagency Strategy for the Implementation of the Federal Wildland Fire Policy, entire text
  9. ^ National Wildfire Coordinating Group Communicator's Guide For Wildland Fire Management, entire text
  10. ^ Government of Canada. Wildfires in Canada; 2009-02-04 [Retrieved 2009-07-09].
  11. ^ Graham, et al., 36
  12. ^ a b Graham, et al., 12.
  13. ^ National Wildfire Coordinating Group Communicator's Guide For Wildland Fire Management, 4-6.
  14. ^ a b National Wildfire Coordinating Group. National Wildfire Coordinating Group Fireline Handbook, Appendix B: Fire Behavior [PDF]; April, 2006 [Retrieved 2008-12-11].
  15. ^ National Interagency Fire Center. Fire Information - Wildland Fire Statistics [Retrieved 2009-06-26].
  16. ^ US Forest Service MODIS Active Fire Mapping Program. Definition of Map Terms [Retrieved 2009-07-07].
  17. ^ Glossary of Wildland Fire Terminology, 156
  18. ^ a b Alvarado, et al., 66-68
  19. ^ Michigan State University Extension. Understanding Wildfire Behavior in Michigan; April 2004 [Retrieved 2009-07-15].
  20. ^ Olson, et al., 2-3
  21. ^ Scott, A. The Pre-Quaternary history of fire. Palaeogeography Palaeoclimatology Palaeoecology. 2000;164:281. doi:10.1016/S0031-0182(00)00192-9.
  22. ^ National Wildfire Coordinating Group. Wildfire Prevention Strategies [PDF]; March 1998 [Retrieved 2008-12-03]; p. 17.
  23. ^ Fire in the hole. Smithsonian Magazine. May 2005 [Retrieved 2009-07-30].
  24. ^ Introduction to wildland fire. 2nd ed. John Wiley and Sons; 1996 [Retrieved 26 Jan 2010]. p. 65.
  25. ^ UCAN News. News 8 Investigation: SDG&E Could Be Liable For Power Line Wildfires; 2007-11-05 [Retrieved 2009-07-20].
  26. ^ The Associated Press. TheStar online. Orangutans in losing battle with slash-and-burn Indonesian farmers; 16 November 2006 [Retrieved 2008-12-01].
  27. ^ Karki, 7.
  28. ^ Karki, 4.
  29. ^ a b National Wildfire Coordinating Group Communicator's Guide For Wildland Fire Management, 3.
  30. ^ Associated Press. MSNBC. Ashes cover areas hit by Southern Calif. fires; 2008-11-15 [Retrieved 2008-12-04].
  31. ^ US Forest Service. Influence of Forest Structure on Wildfire Behavior and the Severity of Its Effects [PDF]; November 2003 [Retrieved 2008-11-19].
  32. ^ Federal Emergency Management Agency (FEMA). Prepare for a Wildfire [Retrieved 2008-12-01].
  33. ^ Glossary of Wildland Fire Terminology, 74.
  34. ^ de Sousa Costa and Sandberg, 229-230.
  35. ^ Massachusetts Institute of Technology (MIT). Archimedes Death Ray: Idea Feasibility Testing; October 2005 [Retrieved 2009-02-01].
  36. ^ European Space Agency. Satellites are tracing Europe's forest fire scars; 2004-07-27 [Retrieved 2009-01-12].
  37. ^ Graham, et al., 10-11.
  38. ^ Graham, et al., 12
  39. ^ National Geographic. Under Fire; July 2008 [Retrieved 2008-12-08].
  40. ^ Graham, et al., 16.
  41. ^ Graham, et al., 9, 16.
  42. ^ Billing, 5
  43. ^ Florida Alliance for Safe Homes (FLASH). Protecting Your Home From Wildfire Damage [PDF] [Retrieved 2009-07-14].
  44. ^ Billing, 5-6
  45. ^ United States Department of Agriculture, Forest Service, Intermountain Research Station. General Technical Report INT-GTR-299 - Mann Gulch Fire: A Race That Couldn't Be Won; May 1993 [Retrieved 2009-06-26].
  46. ^ Victorian Bushfires; 13 March 2009 [Retrieved 26 January 2010].
  47. ^ National Wildfire Coordinating Group Communicator's Guide For Wildland Fire Management, 4.
  48. ^ Graham, et al., 16-17.
  49. ^ Olson, et al., 2
  50. ^ National Wildfire Coordinating Group. The New Generation Fire Shelter [PDF]; March 2003 [Retrieved 2009-01-16]; p. 19.
  51. ^ Glossary of Wildland Fire Terminology, 69.
  52. ^ a b c d Graham, et al., iv.
  53. ^ Graham, et al., 9, 13
  54. ^ British Broadcasting Corporation (BBC) News. Asian peat fires add to warming; 2005-03-09 [Retrieved 2008-12-09].
  55. ^ Graham, et al ., iv, 10, 14
  56. ^ Yale School of Forestry & Environmental Studies. Global Commodities Boom Fuels New Assault on Amazon; 2008-06-19 [Retrieved 2009-07-09].
  57. ^ a b The Nature Conservancy. Global Fire Initiative: Fire and Invasives [Retrieved 2008-12-03].
  58. ^ Graham, et al., iv, 8, 11, 15.
  59. ^ National Oceanic and Atmospheric Administration (NOAA) Satellite and Information Service. Chronological List of U.S. Billion Dollar Events [Retrieved 2009-02-04].
  60. ^ McKenzie, et. al., 893
  61. ^ Graham, et al., 2
  62. ^ Westerling, Al; Hidalgo, Hg; Cayan, Dr; Swetnam, Tw. Warming and earlier spring increase western U.S. Forest wildfire activity. Science (New York, N.Y.). 2006;313(5789):940–3. doi:10.1126/science.1128834. PMID 16825536.
  63. ^ McKenzie, et. al., 894
  64. ^ de Souza Costa and Sandberg, 228
  65. ^ National Wildfire Coordinating Group Communicator's Guide For Wildland Fire Management, 5.
  66. ^ San-Miguel-Ayanz, et al., 364.
  67. ^ Glossary of Wildland Fire Terminology, 73.
  68. ^ National Center for Atmospheric Research. Drought and Wildland Fires [Retrieved 2009-02-03].
  69. ^ Schimel, D., et al. The U.S. Climate Change Science Program. The Effects of Climate Change on Agriculture, Land Resources, Water Resources, and Biodiversity: Synthesis [PDF] [Retrieved 2008-12-05]; p. 183.
  70. ^ The Nature Conservancy. Global Fire Initiative: Fire and Climate Change [Retrieved 2008-12-03].
  71. ^ Interagency Strategy for the Implementation of the Federal Wildland Fire Policy, 3, 37.
  72. ^ Graham, et al., 3.
  73. ^ Keeley, J.E. Future of California floristics and systematics: wildfire threats to the California flora [PDF]. Madrono. 1995 [Retrieved 2009-06-26];42:175–179.
  74. ^ Fire frequency in southern California shrublands: biological effects and management options. In: Brushfires in California wildlands: ecology and resource management. International Association of Wildland Fire; 1995. p. 101–112.
  75. ^ a b van Wagtendonk, 14.
  76. ^ Nepstad, 4, 8-11
  77. ^ Earth Observatory (NASA). Amazon fires on the rise; 2008-03-05 [Retrieved 2009-07-09].
  78. ^ Nepstad, 4
  79. ^ eWater Cooperative Research Center's. Bushfire and Catchments: Effects of Fire on Soils and Erosion [Retrieved 2009-01-08].
  80. ^ Fylingdales Moor a lost landscape rises from the ashes. Current Archaelogy. XIX(226):20–27.
  81. ^ Ecosystem Disturbance, Carbon and Climate. Science. 2008;321:652–653. doi:10.1126/science.1159607. PMID 18669853.
  82. ^ Keeley, J.E. and C.J. Fotheringham. Trace gas emission in smoke-induced germination [PDF]. 1997 [Retrieved 2009-06-26];276:1248–1250.
  83. ^ Flematti GR, Ghisalberti EL, Dixon KW, Trengove RD. A compound from smoke that promotes seed germination. Science. 2004;305(5686):977. doi:10.1126/science.1099944. PMID 15247439.
  84. ^ Karki, 3.
  85. ^ California State University. Section Three: Problems, Cares, Economics, and Species; 1997 [Retrieved 2009-06-26].
  86. ^ Fire. The Australian Experience, 5.
  87. ^ US National Park Service. Giant Sequoias and Fire [Retrieved 2009-06-30].
  88. ^ The Nature Conservancy. Fire Management Assessment of the Caribbean Pine (Pinus caribea) Forest Ecosystems on Andros and Abaco Islands, Bahamas; 2004 September [Retrieved 2009-08-27].
  89. ^ American Geophysical Union fall meeting; 2003.
  90. ^ Fromm, M.; Stocks, B.; Servranckx, R.; Lindsey, D. Smoke in the Stratosphere: What Wildfires have Taught Us About Nuclear Winter; abstract #U14A-04. In: [cited 2009-02-04].
  91. ^ Graham, et al., 17
  92. ^ National Center for Atmospheric Research. Geophysical Research Letters. Wildfires Cause Ozone Pollution to Violate Health Standards; 13 October 2008 [Retrieved 2009-02-04].
  93. ^ John R. Scala, et al. American Meteorological Society. Meteorological Conditions Associated with the Rapid Transport of Canadian Wildfire Products into the Northeast during 5–8 July 2002 [PDF] [Retrieved 2009-02-04].
  94. ^ US Forest Service. User Assessment of Smoke-Dispersion Models for Wildland Biomass Burning [PDF]; December 1996 [Retrieved 2009-02-06].
  95. ^ Impact of wildfires on the air quality of Mexico City, 1992-1999. Environmental Pollution. 2002;117(2):243–253. doi:10.1016/S0269-7491(01)00277-9.
  96. ^ Nicholas School of the Environment and Earth Sciences of Duke University. Quantification of the health impacts associated with fine particulate matter due to wildfires. MS Thesis.; 2008.
  97. ^ The amount of carbon released from peat and forest fires in Indonesia during 1997. Nature. 2002-07-11;420:61–65. doi:10.1038/nature01131.
  98. ^ Center for International Forestry Research. Fires in Indonesia: Causes, Costs, and Policy Implications (CIFOR Occasional Paper No. 38) [PDF]; February 2003 [Retrieved 2009-02-06].
  99. ^ Baumgardner, D. et al. Warming of the Arctic lower stratosphere by light absorbing particles. In: American Geophysical Union fall meeting. 2003.
  100. ^ a b Fire in the European Mediterranean: History. AridLands Newsletter. November/December 2003 [Retrieved 2009-07-17];54.
  101. ^ a b Rackham, 229-230
  102. ^ History of Fire in Land-Use Systems of the Baltic Region: Implications on the Use of Prescribed Fire in Forestry, Nature Conservation and Landscape Management. In: First Baltic Conference on Forest Fires. Global Fire Monitoring Center (GFMC); 5–9 May 1998.
  103. ^ "Wildland fire - An American legacy", 4, 5, 9, 11
  104. ^ Fire and alluvial chronology in Yellowstone National Park: Climatic and intrinsic controls on Holocene geomorphic processes. GSA Bulletin. 1995;(107):1211–1230.
  105. ^ Pitkänen, et. al., 15-16, 27-30
  106. ^ J. R. Marlon, P. J. Bartlein, C. Carcaillet, D. G. Gavin, S. P. Harrison, P. E. Higuera, F. Joos, M. J. Power, I. C. Prentice. Climate and human influences on global biomass burning over the past two millennia. Nature Geoscience. 2008;1:697-702. doi:10.1038/ngeo313. University of Oregon Summary, accessed 2 Feb 2010
  107. ^ Karki, 6.
  108. ^ van Wagtendonk, 1156.
  109. ^ Interagency Strategy for the Implementation of the Federal Wildland Fire Policy, 42.
  110. ^ San-Miguel-Ayanz, et al., 361.
  111. ^ Karki, 7, 11-19.
  112. ^ Nepstad, 16
  113. ^ Fire. The Australian Experience, 7.
  114. ^ Karki, 27.
  115. ^ Smokeybear.com. Smokey's Journey [Retrieved 26 January 2010].
  116. ^ MSN Encarta. Backburn [Retrieved 2009-07-09].
  117. ^ UK: The Role of Fire in the Ecology of Heathland in Southern Britain. International Forest Fire News. January 1998;18:80–81.
  118. ^ SmokeyBear.com. Prescribed Fires [Retrieved 2008-11-21].
  119. ^ Fire. The Australian Experience, 5-6.
  120. ^ Graham, et al., 15.
  121. ^ Peuch, 3.
  122. ^ US Forest Service. Forest biomass utilization decreases wildfire risk and dependence on foreign oil [PDF]; October 2008 [Retrieved 2009-02-03].
  123. ^ van Wagtendonk, 1164
  124. ^ Graham, et. al., 32-33.
  125. ^ CAL FIRE. California’s Fire Hazard Severity Zone Update and Building Standards Revision [PDF]; May 2007 [Retrieved 2008-12-18].
  126. ^ State of California. California Senate Bill No. 1595, Chapter 366 [PDF]; 2008-09-27 [Retrieved 2008-12-18].
  127. ^ Karki, 14.
  128. ^ Graham, et al., page 4
  129. ^ San-Miguel-Ayanz, et al., 362.
  130. ^ a b An Integration of Remote Sensing, GIS, and Information Distribution for Wildfire Detection and Management [PDF]. Photogrammetric Engineering and Remote Sensing. October 1998 [Retrieved 2009-06-26];64(10):977–985. Error: Bad DOI specified!.
  131. ^ Canadian Broadcasting Corporation (CBC) Digital Archives. Radio communication keeps rangers in touch; 21 August 1957 [Retrieved 2009-02-06].
  132. ^ Alabama Forestry Commission. Wildfire Detection and Control [Retrieved 2009-01-12].
  133. ^ "Evaluation of three wildfire smoke detection systems", 4
  134. ^ Washington University in St. Louis. Mobile Agent Middleware for Sensor Networks: An Application Case Study [PDF]; 2004-11-29 [archived 2007-01-03; Retrieved 2009-01-15].
  135. ^ Wireless Sensor Network Based System for Fire Endangered Areas. Third International Conference on Information Technology and Applications. July, 2005 [Retrieved 2009-01-15];2(4-7):203–207. doi:10.1109/ICITA.2005.313.
  136. ^ University of Montana - Missoula. Wireless Weather Sensor Networks for Fire Management [Retrieved 2009-01-19].
  137. ^ Massachusetts Institute of Technology (MIT) News. Preventing forest fires with tree power; 2008-09-23 [Retrieved 2009-01-15].
  138. ^ "Evaluation of three wildfire smoke detection systems", 6
  139. ^ San Diego State University. SDSU Tests New Wildfire-Detection Technology; 2005-06-23 [archived 2006-09-01; Retrieved 2009-01-12].
  140. ^ San-Miguel-Ayanz, et al., 366-369, 373-375.
  141. ^ Rochester Institute of Technology. ScienceDaily. New Wildfire-detection Research Will Pinpoint Small Fires From 10,000 feet; 2003-10-04 [Retrieved 2009-01-12].
  142. ^ European Space Agency. Airborne campaign tests new instrumentation for wildfire detection; 2006-10-11 [Retrieved 2009-01-12].
  143. ^ European Space Agency. World fire maps now available online in near-real time; 2006-05-24 [Retrieved 2009-01-12].
  144. ^ European Space Agency. Earth from Space: California’s ‘Esperanza’ fire; 2006-03-11 [Retrieved 2009-01-12].
  145. ^ National Oceanic and Atmospheric Administration (NOAA) Satellite and Information Service. Hazard Mapping System Fire and Smoke Product [Retrieved 2009-01-15].
  146. ^ A probabilistic zonal approach for swarm-inspired wildfire detection using sensor networks. Int. J. Commun. Syst. 2008-06-09;21(10):1047–1073. doi:10.1002/dac.937.
  147. ^ NASA. Automated Wildfire Detection Through Artificial Neural Networks [PDF] [Retrieved 2009-01-15].
  148. ^ Forest fire detection system based on a ZigBee wireless sensor network. Frontiers of Forestry in China. September, 2008 [Retrieved 2009-06-26];3(3):369–374. doi:10.1007/s11461-008-0054-3.
  149. ^ Karki, 16
  150. ^ FOXNews.com. China Makes Snow to Extinguish Forest Fire; 2006-05-18 [Retrieved 2009-07-10].
  151. ^ NASA-Ames Research Center. Disaster Management Applications – Fire [PDF]; 2003 [Retrieved 2009-07-21].
  152. ^ Plucinski, et al., 6
  153. ^ Automatic remote surveillance system for the prevention of forest fires, 2
  154. ^ CBS News. Fighting fire in the forest; 2009-06-17 [Retrieved 2009-06-26].
  155. ^ National Climatic Data Center. Climate of 2008 Wildfire Season Summary; 2008-12-11 [Retrieved 2009-01-07].
  156. ^ onearth.org. Our Trial by Fire; 2007-12-01 [Retrieved 2009-01-07].
  157. ^ Are Big Fires Inevitable? A Report on the National Bushfire Forum, 15.
  158. ^ National Oceanic and Atmospheric Administration (NOAA). Extreme Events: Wild & Forest Fire [Retrieved 2009-01-07].
  159. ^ McKenzie, et al., 899
  160. ^ van Wagtendonk, 14
  161. ^ Interagency Strategy for the Implementation of the Federal Wildland Fire Policy, 38-40.
  162. ^ Simon Fraser University, Department of Statistics and Actuarial Science. Stochastic Modeling of Forest Dynamics - Project Area 3: PROMETHEUS [Retrieved 2009-07-01].
  163. ^ FireModels.org - Fire Behavior and Danger Software, Missoula Fire Sciences Laboratory. FARSITE [archived 2008-02-15; Retrieved 2009-07-01].
  164. ^ College of William & Mary, Department of Applied Science. A Semi-empirical Cellular Automata Model for Wildfire Monitoring From a Geosynchronous Space Platform [PDF]; 2003 [Retrieved 2009-02-05].
  165. ^ Finney, 1-3.

Bibliography

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