Wildfires

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What is wildfire?

Wildfires are unplanned fires that occur in wildlands such as forest, rangelands or grasslands. They can occur naturally (ignited by lightning), or be caused by human activities such as campfires, faulty power lines, and burning crop residues. Other than those ignition sources, wildfires also need fuels and the proper meteorological condition to start and spread.

Fuels refer to anything that can burn, trees, bushes, grasses, fallen leaves. The availability of fuel is determined in large part by management practices and ecosystem processes and . For example, deforestation leaves behind slash, which are highly inflammable. Expansion of fire-resistant invasive annual grasses is one of the dominant factor in largely increasing the number, frequency, and severity of rangeland wildfires in the Northwest[1].

Meteorological conditions, specifically high temperature, low humidity, and wind play a significant role in triggering and sustaining a fire.

  • Low Humidity: Low humidity levels dry out vegetation, making it more susceptible to ignition and promoting the rapid spread of fires.
  • High Temperatures: Hot temperatures contribute to the drying of vegetation, creating favorable conditions for fires.
  • Wind: Wind can carry embers over long distances, accelerate the spread of flames, and make firefighting efforts more challenging.

Wildfires under climate change

Wildfire activities have significantly increased in the past decades in Alaska and the western United States. Statistics show that the number of large fire occurrences, fire extent, fire severity, and fire season length have all increased since 1980. These changes are closely related to climate change both directly and indirectly.

Climate change drives increase in fire activity directly by inducing higher temperatures, reduced winter snowpack, earlier snowmelt, decreased summer precipitation, and increased evaporation. These conditions creates a more favorable condition for the start and spread of wildfires.

Indirectly, climate change drives those changes in wildfire by changing the ecosystems. For example, climate change degrades forest, creates conditions that favor the expansion of fire-resistant invasive species, and promotes beetle outbreaks that have killed millions of acres of trees and resulted in more flammable fuels.

As climate change continues, we can expect wildfire activity to increase, with rising temperatures and persistent droughts affecting wildland ecosystems​.

Impacts of wildfire

Wildfires have significant impacts on environment, human health, and infrastructure. (Drought has extensive impacts across multiple sectors, affecting ecosystems, agriculture, water resources, energy production, commerce, public health, and infrastructure stability.)


Impacts to human health and safety: Larger, more frequent wildfires threaten human safety, infrastructure, and livelihoods. For example, in 2023, the Wanes Gray Fire near Medical Lake, Washington burned through rangeland and timber, destroying 259 structures, and burning over 10,000 acres. In 2015, the Soda Fire burned nearly 280,000 acres in southwest Idaho and southeast Oregon, including 200,000 acres of greater sage-grouse habitat and portions of 41 grazing allotments. Fires of this size are becoming more common in the inland Northwest.

Wildfire smoke impacts human health. Smoke degrades air quality, and can severely affect the health of children, the elderly, pregnant individuals, and individuals with respiratory conditions. Wildfires can also reduce water quality. After a fire, runoff and erosion can increase substantially. This can lead to sedimentation and chemical changes that degrade the quality of aquatic habitat and drinking water.

Loss of sagebrush habitat and conversion to invasive annual grassland: Cheatgrass and other invasive annual grasses produce many seeds and can reestablish very quickly after a wildfire. Native plants like sagebrush and perennial bunchgrasses require more time to reestablish and produce seeds. This leads to a positive feedback loop between invasive annual grasses and wildfire: fire makes room for more cheatgrass, which encourages more fire and so on. Because frequent wildfires make sagebrush recovery nearly impossible, over time, this positive feedback loop can lead to a conversion of sagebrush landscapes to invasive annual grasslands.

Loss of wildlife habitat: Greater sage-grouse (the largest grouse in North America) depend on sagebrush for breeding habitat and forage. More frequent and severe wildfires can reduce sage-grouse habitat. Since 1984, over 22 million acres of sage-grouse habitat have burned in the Great Basin. If current fire trends continue, half of the sage-grouse population in the Great Basin could be gone by the mid-2040s. Other species that are affected by sagebrush habitat reduction include pygmy rabbits, sage thrashers, and sharp-tailed grouse. Loss of wildlife habitat can affect cultural values, and impact the experience of hunters, anglers, and recreationalists.

Impacts to livestock operations: Both wildfire and annual grasses can impact yearly livestock grazing rotations, stocking rates, and rangeland management. Though invasive annual grasses can provide forage for a short period in spring, they dry out quickly and become unpalatable to livestock. Because they outcompete native grasses that are palatable later in the season, invasive annual grasses reduce the availability of late-season forage. The increasing frequency and severity of rangeland fires can also reduce forage amounts. Following a wildfire, public grazing allotments can be closed for several years to allow restoration of burned areas. In these conditions, ranchers and rangeland managers must find alternate sources of summer forage, which can be expensive and time consuming.

Impacts to rangeland carbon sequestration potential: The combination of the invasive grass-fire cycle and the loss of woody plants like sagebrush suggest that less carbon can be stored in annual grass-dominated ecosystems than sagebrush systems. Conversion of deep-rooted perennial systems to shallow-rooted annual grasses can result in the loss of persistent below-ground carbon. Because most of the carbon stored in rangeland systems is stored in the soil, losing below-ground carbon has serious implications for rangeland carbon storage potential.


How will changing wildfire patterns affect Northwest forests?

More frequent and severe fires can slow the regrowth of vegetation and alter the species composition of Northwest forest ecosystems. High-severity fire creates opportunities for establishment of invasive species, such as cheatgrass, and can limit tree regeneration. In Northwest forests, a warming climate coupled with more frequent wildfires will lead to a shift away from shade-tolerant, thin-barked, or fire-intolerant species such as western hemlock, subalpine fir, and Engelmann spruce. Species that are fire-tolerant, thick-barked, and have high seed-dispersal rates, like Douglas-fir and ponderosa pine, are likely to fare well. However, with warmer and drier conditions and more frequent disturbance, there are some locations that will likely shift from forest to shrubland or grassland.

Short interval reburns (fires in areas burned within the last 15-20 years) are also likely to occur with increasing frequency. Frequent reburns can shift species composition toward species that are adapted to frequent fire. Some tree species will have a difficult time regenerating if intervals between fires are short, and shrubs and grasses may dominate for extended periods.

The increasing frequency of wildfire, particularly high-severity wildfires, will usher in more young forests as older, late-successional forests burn. This shift has major implications for species that depend on late-successional forests, such as the Northern spotted owl. However, some species, like deer and elk, could prosper in younger forests.

Fire-intolerant species could be replaced by species that are better able to survive fires. The number of trees in dry forests could decrease, and it could be harder for new trees to grow. Areas that have already burned could burn again more easily, which could affect conifer regrowth. As old forests burn, young forests could become more common, which could harm species that live in old forests. Invasive plants could establish more easily after fires and could outcompete native plants. Fire, drought, insect outbreaks, and invasive species could interact to drive forest change in a warming

Wildfires under climate change

Wildfire activities have significantly increased in the past decades in Alaska and the western United States. Statistics show that the number of large fire occurence, fire extent, fire severity, and fire season length have all increased since 1980. Increases in large fire activity and area burned have been driven by rising temperatures, reduced winter snowpack, earlier snowmelt, reduced summer precipitation and increased evaporation. Under climate change we can expect the wildfire activity to increase as temperatures continue to warm, lengthening the fire season further, and as drought continues to afflict wildland ecosystems.

Wildfire-related risk analysis

Wildfire data

Historical data

Real-time monitoring data

Forecast data (or called "daily to seasonal scale forecast")

Future projection


The Rangeland Analysis Platform is an online tool that visualizes and analyzes vegetation data (including annual forb and grass coverage) for the United States, including the Northwest.

Great Basin Rangeland Fire Probability Map represents the relative probability of large (> 1,000 acres) rangeland fire given an ignition in a given year. Maps are updated yearly.

FuelCast provides monthly fuel and fire forecasts during the growing season to help users stay up to date on fire danger. It is updated monthly during the growing season.


Data Sources

The full set of wildfire frequency and burned acreage data in Figures 1 and 2 comes from the National Interagency Fire Center, which compiles wildfire reports sent from local, state, and federal entities that are involved in fighting fires. These data are available online at: www.nifc.gov/fire-information/statistics. Additional data were provided by the U.S. Forest Service based on a different set of records, referred to as Smokey Bear Reports. Burn severity data, state-by-state acreage totals, and monthly acreage data in Figures 3 through 7 come from the MTBS multi-agency project, which maintains a database of wildfire events across the United States. These data are publicly available at: www.mtbs.gov/direct-download.https://www.mtbs.gov/direct-download


How does fire make an impact?

Wildfire Data Analysis

U.S. Wildfire statistics:

Global fire statistics:


Geospatial Data:

Fire forecast:


Current Situation Viewer: [1]

Resources:


The Wildfire dataset encompasses occurrences of wildfires across the USA spanning from 2000 to 2023. The dataset includes information on the total count of deaths and the number of individuals affected, providing quantitative insights.

Sample Data

Disaster Type Disaster Subype Location Total Deaths Total Affected
Wildfire Forest fire Gainesville, Alachua areas (Alachua district, Florida province), Lafayette, Gulf districts (Florida province) 0 600
Wildfire Forest fire Los Alamos, Rio Arriba, Sandoval, Santa Fe districts (New Mexico province) 0 25400
Wildfire Forest fire Arizona, California, Colorado, Idaho, Montana, Nevada, New Mexico, Oregon, South Dakota, Texas, Utah, Washington, Wyoming, Florida, North Dakota provinces 14 1000


Access the whole dataset here: https://docs.google.com/spreadsheets/d/1L_EbjiHZYTChjEllwEG0LX_4HavbomD3/edit#gid=1887285575

Deaths and Affected numbers on the basis of different Climatological disasters in USA from 2000-2023

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References

1. https://climatedata.imf.org/

  1. ↑ https://www.climatehubs.usda.gov/hubs/northwest/topic/climate-change-and-wildfire-northwest-rangelands
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