Wildfire suppression

Firefighting tactics used to suppress wildfires

Wildfire suppression is a range of firefighting tactics used to suppress wildfires. Firefighting efforts depend on many factors such as the available fuel, the local atmospheric conditions, the features of the terrain, and the size of the wildfire. Because of this wildfire suppression in wild land areas usually requires different techniques, equipment, and training from the more familiar structure fire fighting found in populated areas. Working in conjunction with specially designed aerial firefighting aircraft, fire engines, tools, firefighting foams, fire retardants, and using various firefighting techniques, wildfire trained crews work to suppress flames, construct fire lines, and extinguish flames and areas of heat in order to protect resources and natural wilderness. Wildfire suppression also addresses the issues of the wildland–urban interface, where populated areas border with wild land areas. In the United States and other countries, aggressive wildfire suppression aimed at minimizing fires has often protected and saved significant wildlands, but has sometimes contributed to accumulation of fuel loads, increasing the risk of large, catastrophic fires.

Protection of human life is first priority for firefighters. Since 1995, when arriving on a scene, a fire crew will establish safety zones and escape routes, verify communication is in place, and designate lookouts (known in the U. S. by the acronym LCES, for lookouts, communications, escape routes, safety zones). This allows the firefighters to engage a fire with options for a retreat should their current situation become unsafe. Although other safety zones should be designated, areas already burned generally provide a safe refuge from fire provided they have cooled sufficiently, are accessible, and have burned enough fuels so as to not reignite. Briefings may be done to inform new fire resources of hazards and other pertinent information. A great emphasis is placed on safety and preventing entrapment, a situation where escape from the fire is impossible. Prevention of this situation is reinforced with two training protocols, Ten Standard Firefighting Orders and Eighteen Situations That Shout Watch Out, which warn firefighters of potentially dangerous situations, developed in the aftermath of the Mann Gulch fire. As a last resort, many wildland firefighters carry a fire shelter. In this inescapable situation, the shelter will provide limited protection from radiant and convective heat, as well as superheated air. Entrapment within a fire shelter is called a burnover. In Australia, firefighters rarely carry fireshelters (commonly referred to as "Shake 'N' Bake" shelters); rather, training is given to locate natural shelters or use hand tools to create protection; or, in the instance of 'burnover' in a tanker or other fire appliance, 'fire overrun' training is used. Hazards beyond the fire are posed as well. A very small sample of these include: unstable/hazardous trees, animals, electrical cables, unexploded ordnance, hazardous materials, rolling and falling debris, and lightning.

While wildfire suppression serves human safety and resource protection, the lack of natural fires can be the cause of ecosystem changes, as can the size of fires when they do occur. Fire ecology is accordingly not as simple as many might assume. Across the global grassland and savanna ecosystems, fire suppression is frequently found to be a driver of woody encroachment.

Wildland fire, known in Australia as bush fire, has played a major role in Australia due to arid conditions. Notable fire services tasked with wildfire suppression include NPWS (National Parks and Wildlife Service, NSW), the New South Wales Rural Fire Service, the South Australian Country Fire Service, the Western Australian Parks and Wildlife Service, the Victorian Department of Environment, Land, Water and Planning (DELWP), and the Country Fire Authority.

Canada contains approximately of forest land. Seventy five percent of this is boreal forest, made up primarily of coniferous trees. More than 90 percent of Canadian forest land is publicly owned, and the provincial and territorial governments are responsible for fire suppression activities. The Federal Canadian Interagency Forest Fire Centre (CIFFC) provides operational fire control services and links to all provincial and territorial fire agencies. During a typical year there are over 9,000 forest fires in Canada, burning an average of 2.5 million hectares (ha) or The number of fires and area burned can vary dramatically from year to year. Average suppression costs are $500 million to $1 billion annually. In Canada, two thirds of all forest fires are caused by people, while lightning causes the remaining third. Despite this, lightning fires account for over 85 percent of the area burned in Canada, largely because many of the lightning caused fires occur in remote, inaccessible areas. Currently about ninety percent of forest fires are fought. Generally fires near communities, industrial infrastructure, and forests with high commercial and recreation value are given high priority for suppression efforts. In remote areas and wilderness parks, fires may be left to burn as part of the natural ecological cycle.

Indigenous communities embraced fire as an ally in preserving nature, but once populations began to grow across the U. S., wildfires started to trigger unprecedented destruction of property and sometimes resulted in massive death tolls. Greater impact on people's lives led to government intervention and changes to how wildfires were addressed. One of the first turning points for firefighting philosophies in the U. S. happened in October 1871, the year of the Great Chicago Fire. Six years removed from the Civil War, the Fire destroyed more than 17,000 buildings across the Windy City, upended thousands of lives and devastated their thriving business community, which did not fully recover until the World's Fair came to Chicago in 1893. The Great Chicago Fire left an indelible mark on the city, and much of its lasting impact came from the introduction of more sensible building codes. The same day as the Chicago Fire, a much larger, more deadly, but less discussed fire occurred, which had a more significant influence on the federal government and its role in fire management. The Peshtigo Fire broke out on the morning of October 8, 1871. It burned for three days, and while estimates vary, the consensus is that it killed more than 1,200 people – making it the deadliest wildfire in American history to this day. In addition to the number of people killed, the fire burned more than 1.2 million acres of land and spread to nearby towns, where it caused even more damage. The entire town of Peshtigo was destroyed within an hour of the start of the fire. As the forerunner of the U. S. Forest Service, this was the first time that wildfire management was placed under government purview.

Across the United States, wildfire suppression is administered by land management agencies including the U. S. Forest Service, Bureau of Land Management, U. S. Fish and Wildlife Service, National Park Service, the Bureau of Reclamation, the Army Corps of Engineers, and state departments of forestry. All of these groups contribute to the National Wildfire Coordinating Group and the National Interagency Fire Center. The National Interagency Fire Center hosts the National Interagency Coordination Center (NICC). NICC's primary responsibility is positioning and managing national resources (i. e. Hotshot Crews, smokejumpers, air tankers, incident management teams, National Caterers, mobile shower units, and command repeaters). NICC also serves as clearing house for the dispatch ordering system. Reporting to NICC are 10 Geographic Area Coordination Centers (Alaska, Great Basin, Northern Rockies, Rocky Mountains, Southern California, Northern California, Eastern, Southern, Southwest and Northwest). Under each GACC are several dispatch zones.

Operating in the U. S. within the context of fire use, firefighters may only suppress fire that has become uncontrollable. Conversely, fires or portions of a fire that have previously been engaged by firefighters may be treated as fire use situation and be left to burn. All fire suppression activities are based from an anchor point (such as lake, rock slide, road or other natural or artificial fire break). From an anchor point firefighters can work to contain a wild land fire without the fire outflanking them. Large fires often become extended campaigns. Incident command posts (ICPs) and other temporary fire camps are constructed to provide food, showers, and rest to fire crews. Weather conditions and fuel conditions are large factors in the decisions made on a fire. Within the U. S., the Energy Release Component (ERC) is a scale relating fuel energy potential to area. The Burning Index (BI) relates flame length to fire spread speed and temperature. The Haines Index (HI) tracks stability and humidity of air over a fire. The Keetch–Byram drought index relates fuels to how quickly they could ignite and to what percentage they should burn. The Lightning Activity Level (LAL) ranks lightning potential into six classes. Mechanical forest thinning combined with controlled ground fire is an effective method for wildfire suppression. Forest thinning and ground burn are more effective in reducing wildfire risk together rather than just thinning or burning. According to an article in the journal of Forest Ecology and Management, “Combined treatments (thinning + burning) tended to have the greatest effect on reducing surface fuels and stand density, and raising modeled crowning and torching indices, as compared to burning or thinning alone.” Thinning and burning also must be continued through follow up maintenance, according to the Western Watersheds Project, but this follow up rarely happens. Forest thinning has brought up concerns that it could increase fire severity, as the sun can reach the lower vegetation and cause additional moisture loss. With climate change already making the ground less humid, according to the NIDIS, “cause of the rapid increase of wildfires over the western U. S. is the rapid increase of surface air vapor pressure deficit, or VPD, a measure of how thirsty the atmosphere is.”

The threat of wildfires does not cease after the flames have passed, as smoldering heavy fuels may continue to burn unnoticed for days after flaming. It is during this phase that either the burn area exterior or the complete burn area of a fire is cooled so as to not reignite another fire.

Constructed firelines, breaks, safety zones and other items may damage soil systems, encouraging erosion from surface run off and gully formation. The loss of plant life from the fire also contributes to erosion. Construction of waterbars, the addition of plants and debris to exposed soils and other measures help to reduce this.

Wildfires can pose risks to human settlement in three main scenarios. The first can happen at the classic wildland–urban interface, where urban or suburban development borders wild land. The second happens at the mixed wildland–urban interface, where homes or small communities are interspersed throughout a wild area, and the boundary between developed and non developed land is undefined. The third occurs in the occluded wildland–urban interface, where pockets of wild land are enclosed within cities. Expansive urbanization and other human activity in areas adjacent to wildlands is a primary reason for the catastrophic structural losses experienced in wildfires. Continued development of wildland–urban interface firefighting measures and the rebuilding of structures destroyed by fires has been met with criticism. Fuel buildup can result in costly, devastating fires as more new houses and ranches are built adjacent to wilderness areas. However, the population growth in these fringe areas discourages the use of current fuel management techniques. Smoke from fires is an irritant and a pollutant. Attempts to thin out the fuel load may be met with opposition due to the desirability of forested areas. Wildland goals may be further resisted because of endangered species protections and habitat preservation. Additionally, federal policies that cover wildland areas usually differ from local and state policies that govern urban lands. In North America, the belief that fire suppression has substantially reduced the average annual area burned is widely held by resource managers, and is often thought to be self evident. However, this belief has been the focus of vocal debate in the scientific literature.

Wildfire suppression requires specialist personnel and equipment. Notable examples include smokejumpers (firefighters who parachute into remote areas) and helicopter support.

The success of wildfire suppression techniques is debated amongst the scientific community. A number of studies (produced during the 1990s) using Ontario government fire records compared either the number of fires or the average fire size between areas with and without aggressive fire suppression policies.