title: Wildfire

text: In the summer of 1974–1975 (southern hemisphere), Australia suffered its worst recorded wildfire, when 15% of Australia's land mass suffered "extensive fire damage". Fires that summer burned up an estimated . In Australia, the annual number of hot days (above 35 °C) and very hot days (above 40 °C) has increased significantly in many areas of the country since 1950. The country has always had bushfires but in 2019, the extent and ferocity of these fires increased dramatically. For the first time catastrophic bushfire conditions were declared for Greater Sydney. New South Wales and Queensland declared a state of emergency but fires were also burning in South Australia and Western Australia.


title: Wildfire

text: In 2019, extreme heat and dryness caused massive wildfires in Siberia, Alaska, Canary Islands, Australia, and in the Amazon rainforest. The fires in the latter were caused mainly by illegal logging. The smoke from the fires expanded on huge territory including major cities, dramatically reducing air quality.


title: Wildfire

text: As of August 2020, the wildfires in that year were 13% worse than in 2019 due primarily to climate change and deforestation. The Amazon rainforest's existence is threatened by fires. According to Mike Barrett, Executive Director of Science and Conservation at WWF-UK, if this rainforest is destroyed "we lose the fight against climate change. There will be no going back.” Record-breaking wildfires in 2021 occurred in Turkey, Greece, California and Russia, thought to be linked to climate change.


title: Wildfire

text: Wildfires release large amounts of carbon dioxide, black and brown carbon particles, and ozone precursors such as volatile organic compounds and nitrogen oxides (NOx) into the atmosphere. These emissions affect radiation, clouds, and climate on regional and even global scales. Wildfires also emit substantial amounts of semi-volatile organic species that can partition from the gas phase to form secondary organic aerosol (SOA) over hours to days after emission. In addition, the formation of the other pollutants as the air is transported can lead to harmful exposures for populations in regions far away from the wildfires. While direct emissions of harmful pollutants can affect first responders and local residents, wildfire smoke can also be transported over long distances and impact air quality across local, regional, and global scales. Whether transported smoke plumes are relevant for surface air quality depends on where they exist in the atmosphere, which in turn depends on the initial injection height of the convective smoke plume into the atmosphere. Smoke that is injected above the planetary boundary layer (PBL) may be detectable from spaceborne satellites and play a role in altering the Earth's energy budget, but would not mix down to the surface where it would impact air quality and human health. Alternatively, smoke confined to a shallow PBL (through nighttime stable stratification of the atmosphere or terrain trapping) may become particularly concentrated and problematic for surface air quality. Wildfire intensity and smoke emissions are not constant throughout the fire lifetime and tend to follow a diurnal cycle that peaks in late afternoon and early evening, and which may be reasonably approximated using a monomodal or bimodal normal distribution.


title: Wildfire

text: Over the past century, wildfires have accounted for 20-25% of global carbon emissions, the remainder from human activities. Global carbon emissions from wildfires through August 2020 equaled the average annual emissions of the European Union. In 2020, the carbon released by California's wildfires were significantly larger than the state's other carbon emissions.


title: Wildfire

text: Wildfire's occurrence throughout the history of terrestrial life invites conjecture that fire must have had pronounced evolutionary effects on most ecosystems' flora and fauna. Wildfires are common in climates that are sufficiently moist to allow the growth of vegetation but feature extended dry, hot periods. Such places include the vegetated areas of Australia and Southeast Asia, the veld in southern Africa, the fynbos in the Western Cape of South Africa, the forested areas of the United States and Canada, and the Mediterranean Basin.


title: Wildfire

text: High-severity wildfire creates complex early seral forest habitat (also called “snag forest habitat”), which often has higher species richness and diversity than unburned old forest. Plant and animal species in most types of North American forests evolved with fire, and many of these species depend on wildfires, and particularly high-severity fires, to reproduce and grow. Fire helps to return nutrients from plant matter back to soil, the heat from fire is necessary to the germination of certain types of seeds, and the snags (dead trees) and early successional forests created by high-severity fire create habitat conditions that are beneficial to wildlife. Early successional forests created by high-severity fire support some of the highest levels of native biodiversity found in temperate conifer forests. Post-fire logging has no ecological benefits and many negative impacts; the same is often true for post-fire seeding.


title: Wildfire

text: Although some ecosystems rely on naturally occurring fires to regulate growth, some ecosystems suffer from too much fire, such as the chaparral in southern California and lower-elevation deserts in the American Southwest. The increased fire frequency in these ordinarily fire-dependent areas has upset natural cycles, damaged native plant communities, and encouraged the growth of non-native weeds. Invasive species, such as "Lygodium microphyllum" and "Bromus tectorum", can grow rapidly in areas that were damaged by fires. Because they are highly flammable, they can increase the future risk of fire, creating a positive feedback loop that increases fire frequency and further alters native vegetation communities.


title: Wildfire

text: In the Amazon rainforest, drought, logging, 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. Fires in the rainforest threaten its collection of diverse species and produce large amounts of CO. Also, fires in the rainforest, along with drought and human involvement, could damage or destroy more than half of the Amazon rainforest by 2030. Wildfires generate ash, reduce the availability of organic nutrients, and cause an increase in water runoff, eroding away other nutrients and creating flash flood conditions. A 2003 wildfire in the North Yorkshire Moors burned off 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. 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.


title: Wildfire

text: In tundra there is a natural pattern of accumulation of fuel and wildfire which varies depending on the nature of vegetation and terrain. Research in Alaska has shown fire-event return intervals, (FRIs) that typically vary from 150 to 200 years with dryer lowland areas burning more frequently than wetter upland areas.


title: Wildfire

text: Plants 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. For example, 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. Dense bark, shedding lower branches, and high water content in external structures may also protect trees from rising temperatures. Fire-resistant seeds and reserve shoots that sprout after a fire encourage species preservation, as embodied by pioneer species. Smoke, charred wood, and heat can stimulate the germination of seeds in a process called "serotiny". Exposure to smoke from burning plants promotes germination in other types of plants by inducing the production of the orange butenolide.


title: Wildfire

text: Grasslands in Western Sabah, Malaysian pine forests, and Indonesian "Casuarina" forests are believed to have resulted from previous periods of fire. Chamise deadwood litter is low in water content and flammable, and the shrub quickly sprouts after a fire. Cape lilies lie dormant until flames brush away the covering and then blossom almost overnight. Sequoia rely on periodic fires to reduce competition, release seeds from their cones, and clear the soil and canopy for new growth. 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.


title: Wildfire

text: Most of the Earth's weather and air pollution resides in the troposphere, the part of the atmosphere that extends from the surface of the planet to a height of about . The vertical lift of a severe thunderstorm or pyrocumulonimbus can be enhanced in the area of a large wildfire, which can propel smoke, soot, and other particulate matter as high as the lower stratosphere. 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. Pyrocumulus clouds can reach over wildfires. Satellite observation of smoke plumes from wildfires revealed that the plumes could be traced intact for distances exceeding . Computer-aided models such as CALPUFF may help predict the size and direction of wildfire-generated smoke plumes by using atmospheric dispersion modeling.


title: Wildfire

text: Wildfires can affect local atmospheric pollution, and release carbon in the form of carbon dioxide. Wildfire emissions contain fine particulate matter which can cause cardiovascular and respiratory problems. Increased fire byproducts in the troposphere can increase ozone concentration beyond safe levels. 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 tons) of CO into the atmosphere, which is between 13%–40% of the annual global carbon dioxide emissions from burning fossil fuels.


title: Wildfire

text: In June and July 2019, fires in the Arctic emitted more than 140 megatons of carbon dioxide, according to an analysis by CAMS. To put that into perspective this amounts to the same amount of carbon emitted by 36 million cars in a year. The recent wildfires and their massive CO emissions mean that it will be important to take them into consideration when implementing measures for reaching greenhouse gas reduction targets accorded with the Paris climate agreement. Due to the complex oxidative chemistry occurring during the transport of wildfire smoke in the atmosphere, the toxicity of emissions was indicated to increase over time.


title: Wildfire

text: Atmospheric models suggest that these concentrations of sooty particles could increase absorption of incoming solar radiation during winter months by as much as 15%. The Amazon is estimated to hold around 90 billion tons of carbon. As of 2019, earth's atmosphere has 415 parts per million of carbon, and the destruction of the Amazon would add about 38 parts per million.


title: Wildfire

text: Wildfire prevention refers to the preemptive methods aimed at reducing the risk of fires as well as lessening its severity and spread. Prevention techniques aim to manage air quality, maintain ecological balances, protect resources, and to affect future fires. North American firefighting policies permit naturally caused fires to burn to maintain their ecological role, so long as the risks of escape into high-value areas are mitigated. However, prevention policies must consider the role that humans play in wildfires, since, for example, 95% of forest fires in Europe are related to human involvement. 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.


title: Wildfire

text: 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, characters from the Disney movie "Bambi", and the official mascot of the U.S. Forest Service, Smokey Bear. Reducing human-caused ignitions may be the most effective means of reducing unwanted wildfire. Alteration of fuels is commonly undertaken when attempting to affect future fire risk and behavior.


title: Wildfire

text: Wildfire prevention programs around the world may employ techniques such as "wildland fire use" (WFU) and "prescribed or controlled burns". "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.


title: Wildfire

text: According to the United States Fish and Wildlife Service, in rugged, steep, or highly inaccessible terrain where people are not threatened, wildland fire use can help avoid putting firefighters at unreasonable risk. Other objectives can include maintenance of healthy forests, rangelands, and wetlands, and support of ecosystem diversity.


title: Wildfire

text: Strategies for wildfire prevention, detection, control and suppression have varied over the years. One common and inexpensive technique to reduce the risk of uncontrolled wildfires is controlled burning: intentionally igniting smaller less-intense fires to minimize the amount of flammable material available for a potential wildfire. Vegetation may be burned periodically to limit the accumulation of plants and other debris that may serve as fuel, while also maintaining high species diversity. Jan Van Wagtendonk, a biologist at the Yellowstone Field Station, claims that Wildfire itself is "the most effective treatment for reducing a fire's rate of spread, fireline intensity, flame length, and heat per unit of area." While other people claim that controlled burns and a policy of allowing some wildfires to burn is the cheapest method and an ecologically appropriate policy for many forests, they tend not to take into account the economic value of resources that are consumed by the fire, especially merchantable timber. Some studies conclude that while fuels may also be removed by logging, such thinning treatments may not be effective at reducing fire severity under extreme weather conditions.


title: Wildfire

text: However, multi-agency studies conducted by the United States Department of Agriculture, the U.S. Forest Service Pacific Northwest Research Station, and the School of Forestry and Bureau of Business and Economic Research at the University of Montana, through strategic assessments of fire hazards and the potential effectiveness and costs of different hazard reduction treatments, clearly demonstrate that the most effective short- and long-term forest fire hazard reduction strategy and by far the most cost-effective method to yield long-term mitigation of forest fire risk is a comprehensive fuel reduction strategy that involves mechanical removal of overstocked trees through commercial logging and non-commercial thinning with no restrictions on the size of trees that are removed, resulting in considerably better long-term results compared to a non-commercial "thin below" operation or a commercial logging operation with diameter restrictions. Starting with a forest with a "high risk" of fire and a pre-treatment crowning index of 21, the "thin from below" practice of removing only very small trees resulted in an immediate crowning index of 43, with 29% of the post-treatment area rated "low risk" immediately and only 20% of the treatment area remaining "low risk" after 30 years, at a cost (net economic loss) of $439 per acre treated. Again starting with a forest at "high risk" of fire and a crowning index of 21, the strategy involving non-commercial thinning and commercial logging with size-restrictions resulted in an crowning index of 43 immediately post-treatment with 67% of the area considered "low risk" and 56% of the area remaining low risk after 30 years, at a cost (net economic loss) of $368 per acre treated. On the other hand, starting with a forest at "high risk" of fire and the same crowning index of 21, a comprehensive fire hazard reduction treatment strategy, without restrictions on size of trees removed, resulted in an immediate crowning index of 61 post-treatment with 69% of the treated area rated "low risk" immediately and 52% of the treated area remaining "low risk" after 30 years, with positive revenue (a net economic gain gain) of $8 per acre.


title: Wildfire

text: 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 structure. Communities in the Philippines also maintain fire lines wide between the forest and their village, and patrol these lines during summer months or seasons of dry weather. Continued residential development in fire-prone areas and rebuilding structures destroyed by fires has been met with criticism. The ecological benefits of fire are often overridden by the economic and safety benefits of protecting structures and human life.


title: Wildfire

text: Fast and effective detection is a key factor in wildfire fighting. Early detection efforts were focused on early response, accurate results in both daytime and nighttime, and the ability to prioritize fire danger. Fire lookout towers were used in the United States in the early 20th century and fires were reported using telephones, carrier pigeons, and heliographs. 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 the delivery of satellite-based fire information in approximately four hours.


title: Wildfire

text: 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. A government report on a recent trial of three automated camera fire detection systems in Australia did, however, conclude "...detection by the camera systems was slower and less reliable than by a trained human observer". 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.


title: Wildfire

text: 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. These may be battery-powered, solar-powered, or "tree-rechargeable": able to recharge their battery systems using the small electrical currents in plant material. 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. Additional capabilities such as night vision, brightness detection, and color change detection may also be incorporated into sensor arrays.


title: Wildfire

text: Satellite and aerial monitoring through the use of planes, helicopter, or UAVs 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. 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 . 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. However, satellite detection is prone to offset errors, anywhere from for MODIS and AVHRR data and up to for GOES data. 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 may also limit the effectiveness of satellite imagery. Global Forest Watch provides detailed daily updates on fire alerts. These are sourced from NASA FIRMS. “VIIRS Active Fires.”


title: Wildfire

text: In 2015 a new fire detection tool is in operation at the U.S. Department of Agriculture (USDA) Forest Service (USFS) which uses data from the Suomi National Polar-orbiting Partnership (NPP) satellite to detect smaller fires in more detail than previous space-based products. The high-resolution data is used with a computer model to predict how a fire will change direction based on weather and land conditions. The active fire detection product using data from Suomi NPP's Visible Infrared Imaging Radiometer Suite (VIIRS) increases the resolution of fire observations to 1,230 feet (375 meters). Previous NASA satellite data products available since the early 2000s observed fires at 3,280 foot (1 kilometer) resolution. The data is one of the intelligence tools used by the USFS and Department of Interior agencies across the United States to guide resource allocation and strategic fire management decisions. The enhanced VIIRS fire product enables detection every 12 hours or less of much smaller fires and provides more detail and consistent tracking of fire lines during long-duration wildfires – capabilities critical for early warning systems and support of routine mapping of fire progression. Active fire locations are available to users within minutes from the satellite overpass through data processing facilities at the USFS Remote Sensing Applications Center, which uses technologies developed by the NASA Goddard Space Flight Center Direct Readout Laboratory in Greenbelt, Maryland. The model uses data on weather conditions and the land surrounding an active fire to predict 12–18 hours in advance whether a blaze will shift direction. The state of Colorado decided to incorporate the weather-fire model in its firefighting efforts beginning with the 2016 fire season.


title: Wildfire

text: In 2014, an international campaign was organized in South Africa's Kruger National Park to validate fire detection products including the new VIIRS active fire data. In advance of that campaign, the Meraka Institute of the Council for Scientific and Industrial Research in Pretoria, South Africa, an early adopter of the VIIRS 375 m fire product, put it to use during several large wildfires in Kruger.


title: Wildfire

text: The demand for timely, high-quality fire information has increased in recent years. Wildfires in the United States burn an average of 7 million acres of land each year. For the last 10 years, the USFS and Department of Interior have spent a combined average of about $2–4 billion annually on wildfire suppression.


title: Wildfire

text: Wildfire suppression depends on the technologies available in the area in which the wildfire occurs. In less developed nations the techniques used can be as simple as throwing sand or beating the fire with sticks or palm fronds. In more advanced nations, the suppression methods vary due to increased technological capacity. Silver iodide can be used to encourage snow fall, while fire retardants and water can be dropped onto fires by unmanned aerial vehicles, planes, and helicopters. 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 under extreme weather conditions are difficult to suppress without a change in the weather. Wildfires in Canada and the US burn an average of per year.


title: Wildfire

text: Above all, fighting wildfires can become deadly. 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, which can make fires particularly dangerous. For example, during the 1949 Mann Gulch fire in Montana, United States, thirteen smokejumpers died when they lost their communication links, became disoriented, and were overtaken by the fire. 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.


title: Wildfire

text: The suppression of wild fires takes up a large amount of a country's gross domestic product which directly affects the country's economy. While costs vary wildly from year to year, depending on the severity of each fire season, in the United States, local, state, federal and tribal agencies collectively spend tens of billions of dollars annually to suppress wildfires. In the United States, it was reported that approximately $6 billion was spent between 2004–2008 to suppress wildfires in the country. In California, the U.S. Forest Service spends about $200 million per year to suppress 98% of wildfires and up to $1 billion to suppress the other 2% of fires that escape initial attack and become large.


title: Wildfire

text: Wildland fire fighters face several life-threatening hazards including heat stress, fatigue, smoke and dust, as well as the risk of other injuries such as burns, cuts and scrapes, animal bites, and even rhabdomyolysis. Between 2000–2016, more than 350 wildland firefighters died on-duty.


title: Wildfire

text: Especially in hot weather conditions, fires present the risk of heat stress, which can entail feeling heat, fatigue, weakness, vertigo, headache, or nausea. Heat stress can progress into heat strain, which entails physiological changes such as increased heart rate and core body temperature. This can lead to heat-related illnesses, such as heat rash, cramps, exhaustion or heat stroke. Various factors can contribute to the risks posed by heat stress, including strenuous work, personal risk factors such as age and fitness, dehydration, sleep deprivation, and burdensome personal protective equipment. Rest, cool water, and occasional breaks are crucial to mitigating the effects of heat stress.


title: Wildfire

text: Smoke, ash, and debris can also pose serious respiratory hazards to wildland firefighters. The smoke and dust from wildfires can contain gases such as carbon monoxide, sulfur dioxide and formaldehyde, as well as particulates such as ash and silica. To reduce smoke exposure, wildfire fighting crews should, whenever possible, rotate firefighters through areas of heavy smoke, avoid downwind firefighting, use equipment rather than people in holding areas, and minimize mop-up. Camps and command posts should also be located upwind of wildfires. Protective clothing and equipment can also help minimize exposure to smoke and ash.


title: Wildfire

text: Firefighters are also at risk of cardiac events including strokes and heart attacks. Firefighters should maintain good physical fitness. Fitness programs, medical screening and examination programs which include stress tests can minimize the risks of firefighting cardiac problems. Other injury hazards wildland firefighters face include slips, trips, falls, burns, scrapes, and cuts from tools and equipment, being struck by trees, vehicles, or other objects, plant hazards such as thorns and poison ivy, snake and animal bites, vehicle crashes, electrocution from power lines or lightning storms, and unstable building structures.


title: Wildfire

text: The U.S. Forest Service publishes guidelines for the minimum distance a firefighter should be from a flame. As stated in the National Wildfire Coordinating Group's Incident Response Pocket Guide: "A safety zone is an area where a firefighter can survive without a fire shelter" and should be "...at least four times the maximum continuous flame height." However this figure only takes into account the effects of radiant heat and does not consider topography nor wind.


title: Wildfire

text: Safety Zones can natural features such as rock screes, meadows, and river bars; or human-made features such a parking lots or areas that have been cleared of vegetation through mechanical means.


title: Wildfire

text: Fire retardants are used to slow wildfires by inhibiting combustion. They are aqueous solutions of ammonium phosphates and ammonium sulfates, as well as thickening agents. The decision to apply retardant depends on the magnitude, location and intensity of the wildfire. In certain instances, fire retardant may also be applied as a precautionary fire defense measure.


title: Wildfire

text: Typical fire retardants contain the same agents as fertilizers. Fire retardants may also affect water quality through leaching, eutrophication, or misapplication. Fire retardant's effects on drinking water remain inconclusive. Dilution factors, including water body size, rainfall, and water flow rates lessen the concentration and potency of fire retardant. Wildfire debris (ash and sediment) clog rivers and reservoirs increasing the risk for floods and erosion that ultimately slow and/or damage water treatment systems. There is continued concern of fire retardant effects on land, water, wildlife habitats, and watershed quality, additional research is needed. However, on the positive side, fire retardant (specifically its nitrogen and phosphorus components) has been shown to have a fertilizing effect on nutrient-deprived soils and thus creates a temporary increase in vegetation.


title: Wildfire

text: The current USDA procedure maintains that the aerial application of fire retardant in the United States must clear waterways by a minimum of 300 feet to safeguard effects of retardant runoff. Aerial uses of fire retardants are required to avoid application near waterways and endangered species (plant and animal habitats). After any incident of fire retardant misapplication, the U.S. Forest Service requires reporting and assessment impacts be made to determine a mitigation, remediation, and/or restrictions on future retardant uses in that area.


title: Wildfire

text: Wildfire modeling is concerned with numerical simulation of wildfires to comprehend and predict fire behavior. Wildfire modeling aims to aid wildfire suppression, increase the safety of firefighters and the public, 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 wind speed 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. 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 large wildfires than by small fires.


title: Wildfire

text: Wildfire risk is the chance that a wildfire will start in or reach a particular area and the potential loss of human values if it does. Risk is dependent on variable factors such as human activities, weather patterns, availability of wildfire fuels, and the availability or lack of resources to suppress a fire. Wildfires have continually been a threat to human populations. However, human-induced geographical and climatic changes are exposing populations more frequently to wildfires and increasing wildfire risk. It is speculated that the increase in wildfires arises from a century of wildfire suppression coupled with the rapid expansion of human developments into fire-prone wildlands. Wildfires are naturally occurring events that aid in promoting forest health. Global warming and climate changes are causing an increase in temperatures and more droughts nationwide which contributes to an increase in wildfire risk.


title: Wildfire

text: The most noticeable adverse effect of wildfires is the destruction of property. However, the release of hazardous chemicals from the burning of wildland fuels also significantly impacts health in humans.


title: Wildfire

text: Wildfire smoke is composed primarily of carbon dioxide and water vapor. Other common smoke components present in lower concentrations are carbon monoxide, formaldehyde, acrolein, polyaromatic hydrocarbons, and benzene. Small particulates suspended in air which come in solid form or in liquid droplets are also present in smoke. 80 -90% of wildfire smoke, by mass, is within the fine particle size class of 2.5 micrometers in diameter or smaller.


title: Wildfire

text: Despite carbon dioxide's high concentration in smoke, it poses a low health risk due to its low toxicity. Rather, carbon monoxide and fine particulate matter, particularly 2.5 µm in diameter and smaller, have been identified as the major health threats. Other chemicals are considered to be significant hazards but are found in concentrations that are too low to cause detectable health effects.


title: Wildfire

text: The degree of wildfire smoke exposure to an individual is dependent on the length, severity, duration, and proximity of the fire. People are exposed directly to smoke via the respiratory tract through inhalation of air pollutants. Indirectly, communities are exposed to wildfire debris that can contaminate soil and water supplies.


title: Wildfire

text: The U.S. Environmental Protection Agency (EPA) developed the air quality index (AQI), a public resource that provides national air quality standard concentrations for common air pollutants. The public can use this index as a tool to determine their exposure to hazardous air pollutants based on visibility range.


title: Wildfire

text: Fire ecologist Leda Kobziar found that wildfire smoke distributes microbial life on a global level. She stated, "There are numerous allergens that we’ve found in the smoke. And so it may be that some people who are sensitive to smoke have that sensitivity, not only because of the particulate matter and the smoke but also because there are some biological organisms in it."


title: Wildfire

text: It is well-known that debris and chemicals can runoff into waterways after wildfires making the drinking water sources unsafe. It is also known that wildfires can damage water treatment facilities making drinking water unsafe. Though, even when the water sources and treatment facilities are not damaged, drinking water inside buildings and in buried water distribution systems can be chemically contaminated. After the 2017 Tubbs Fire and 2018 Camp Fire in California hazardous waste levels of chemical contamination were found in multiple public drinking water systems impacted by wildfires. Since 2018, additional wildfires that damaged drinking water distribution systems and plumbing in California and Oregon have caused chemical drinking water contamination. Benzene is one of many chemicals that has been found in the drinking water systems and buildings after wildfires. Benzene can permeate certain plastic pipes and thus require long times to remove from the water distribution system infrastructure and building plumbing. Using a U.S. Environmental Protection Agency model, researchers estimated more than286 days of constant flushing a single contaminated pipe 24 hours per day, 7 days a week were needed to reduce benzene below safe drinking water limits. Temperature increases caused by fires, including wildfires, can cause plastic water pipes to generate toxic chemicals such as benzene into the water that they carry.


title: Wildfire

text: Suspended sediment inputs to streams and reservoirs alter the colour and murkiness of water, yet because of the chance of transporting particle-associated pollutants. Elevated suspended sediment concentrations in drink will build it tough to notice microorganism and viruses, increase microorganism development because of high quantities of adsorbate nutrients, and reduce medical aid effectiveness.


title: Wildfire

text: Importantly, composite suspended sediment particles, instead of primary particles, might dominate the transit of little cohesive sediments through the stream system. microbial communities, organic and inorganic particles, and chemical components are all enclosed within the structure of those composite particles, which may have a negative impact on water quality. Burned aggregates have a lot of bigger sinking velocities than change state particles of equal diameter, which has been attributed to a rise in burned mixture density because of reduced organic content and pore house. Moreover, the impact of soil heating has been ascribed to the aggregation of clay particles into coarser composite particles, probably increasing the concentration of pollutants to composite particles relative to primary particles of equivalent size. Hyperbolic fine sediment storage and maybe delayed unharness of pollutants once fireplace from decaying aggregates are two potential implications of fireplace effects on soil particles.


title: Wildfire

text: After a wildfire, hazards remain. Residents returning to their homes may be at risk from falling fire-weakened trees. Humans and pets may also be harmed by falling into ash pits. The Intergovernmental Panel on Climate Change (IPCC) also reports that wildfires cause significant damage to electric systems, especially in dry regions.


title: Wildfire

text: Other post-fire risks, can increase if other extreme weather follows. For example, wildfires make soil less able to absorb precipitation, so heavy rainfall can result in more severe flooding and damages like mud slides.


title: Wildfire

text: Firefighters are at the greatest risk for acute and chronic health effects resulting from wildfire smoke exposure. Due to firefighters' occupational duties, they are frequently exposed to hazardous chemicals at close proximity for longer periods of time. A case study on the exposure of wildfire smoke among wildland firefighters shows that firefighters are exposed to significant levels of carbon monoxide and respiratory irritants above OSHA-permissible exposure limits (PEL) and ACGIH threshold limit values (TLV). 5–10% are overexposed. The study obtained exposure concentrations for one wildland firefighter over a 10-hour shift spent holding down a fireline. The firefighter was exposed to a wide range of carbon monoxide and respiratory irritants (a combination of particulate matter 3.5 µm and smaller, acrolein, and formaldehyde) levels. Carbon monoxide levels reached up to 160ppm and the TLV irritant index value reached a high of 10. In contrast, the OSHA PEL for carbon monoxide is 30ppm and for the TLV respiratory irritant index, the calculated threshold limit value is 1; any value above 1 exceeds exposure limits.


title: Wildfire

text: Between 2001 and 2012, over 200 fatalities occurred among wildland firefighters. In addition to heat and chemical hazards, firefighters are also at risk for electrocution from power lines; injuries from equipment; slips, trips, and falls; injuries from vehicle rollovers; heat-related illness; insect bites and stings; stress; and rhabdomyolysis.


title: Wildfire

text: Residents in communities surrounding wildfires are exposed to lower concentrations of chemicals, but they are at a greater risk for indirect exposure through water or soil contamination. Exposure to residents is greatly dependent on individual susceptibility. Vulnerable persons such as children (ages 0–4), the elderly (ages 65 and older), smokers, and pregnant women are at an increased risk due to their already compromised body systems, even when the exposures are present at low chemical concentrations and for relatively short exposure periods. They are also at risk for future wildfires and may move away to areas they consider less risky.


title: Wildfire

text: Wildfires affect large numbers of people in Western Canada and the United States. In California alone, more than 350,000 people live in towns and cities in "very high fire hazard severity zones".


title: Wildfire

text: Direct risks to building residents in fire-prone areas can be moderated through design choices such as choosing fire-resistant vegetation, maintaining landscaping to avoid debris accumulation and to create firebreaks, and by selecting fire-retardant roofing materials. Potential compounding issues with poor air quality and heat during warmer months may be addressed with MERV 11 or higher outdoor air filtration in building ventilation systems, mechanical cooling, and a provision of a refuge area with additional air cleaning and cooling, if needed.


title: Wildfire

text: Wildfire smoke contains particulate matter that may have adverse effects upon the human respiratory system. Evidence of the health effects of wildfire smoke should be relayed to the public so that exposure may be limited. Evidence of health effects can also be used to influence policy to promote positive health outcomes.


title: Wildfire

text: Inhalation of smoke from a wildfire can be a health hazard. Wildfire smoke is composed of combustion products i.e. carbon dioxide, carbon monoxide, water vapor, particulate matter, organic chemicals, nitrogen oxides and other compounds. The principal health concern is the inhalation of particulate matter and carbon monoxide.


title: Wildfire

text: Particulate matter (PM) is a type of air pollution made up of particles of dust and liquid droplets. They are characterized into three categories based on the diameter of the particle: coarse PM, fine PM, and ultrafine PM. Coarse particles are between 2.5 micrometers and 10 micrometers, fine particles measure 0.1 to 2.5 micrometers, and ultrafine particle are less than 0.1 micrometer.  Each size can enter the body through inhalation, but the PM impact on the body varies by size. Coarse particles are filtered by the upper airways and these particles can accumulate and cause pulmonary inflammation. This can result in eye and sinus irritation as well as sore throat and coughing. Coarse PM is often composed of materials that are heavier and more toxic that lead to short-term effects with stronger impact.


title: Wildfire

text: Smaller particulate moves further into the respiratory system creating issues deep into the lungs and the bloodstream. In asthma patients, PM causes inflammation but also increases oxidative stress in the epithelial cells. These particulates also cause apoptosis and autophagy in lung epithelial cells. Both processes cause the cells to be damaged and impacts the cell function. This damage impacts those with respiratory conditions such as asthma where the lung tissues and function are already compromised. The third PM type is ultra-fine PM (UFP). UFP can enter the bloodstream like PM however studies show that it works into the blood much quicker. The inflammation and epithelial damage done by UFP has also shown to be much more severe. PM is of the largest concern in regards to wildfire. This is particularly hazardous to the very young, elderly and those with chronic conditions such as asthma, chronic obstructive pulmonary disease (COPD), cystic fibrosis and cardiovascular conditions. The illnesses most commonly with exposure to the fine particles from wildfire smoke are bronchitis, exacerbation of asthma or COPD, and pneumonia. Symptoms of these complications include wheezing and shortness of breath and cardiovascular symptoms include chest pain, rapid heart rate and fatigue.


title: Wildfire

text: Smoke from wildfires can cause health problems, especially for children and those who already have respiratory problems. Several epidemiological studies have demonstrated a close association between air pollution and respiratory allergic diseases such as bronchial asthma.


title: Wildfire

text: An observational study of smoke exposure related to the 2007 San Diego wildfires revealed an increase both in healthcare utilization and respiratory diagnoses, especially asthma among the group sampled. Projected climate scenarios of wildfire occurrences predict significant increases in respiratory conditions among young children. Particulate Matter (PM) triggers a series of biological processes including inflammatory immune response, oxidative stress, which are associated with harmful changes in allergic respiratory diseases.


title: Wildfire

text: Although some studies demonstrated no significant acute changes in lung function among people with asthma related to PM from wildfires, a possible explanation for these counterintuitive findings is the increased use of quick-relief medications, such as inhalers, in response to elevated levels of smoke among those already diagnosed with asthma. In investigating the association of medication use for obstructive lung disease and wildfire exposure, researchers found increases both in the usage of inhalers and initiation of long-term control as in oral steroids. More specifically, some people with asthma reported higher use of quick-relief medications (inhalers). After two major wildfires in California, researchers found an increase in physician prescriptions for quick-relief medications in the years following the wildfires than compared to the year before each occurrence.


title: Wildfire

text: Asthma is one of the most common chronic disease among children in the United States, affecting an estimated 6.2 million children. Research on asthma risk focuses specifically on the risk of air pollution during the gestational period. Several pathophysiology processes are involved are in this. Considerable airway development occurs during the 2nd and 3rd trimester and continues until 3 years of age. It is hypothesized that exposure to these toxins during this period could have consequential effects, as the epithelium of the lungs during this time could have increased permeability to toxins. Exposure to air pollution during parental and pre-natal stage could induce epigenetic changes which are responsible for the development of asthma. Studies have found significant association between PM, NO and development of asthma during childhood despite heterogeneity among studies. Furthermore, maternal exposure to chronic stressors is most likely present in distressed communities, and as this can be correlated with childhood asthma, it may further explain links between early childhood exposure to air pollution, neighborhood poverty, and childhood risk. As well, living in distressed neighborhoods is linked to pollutant source location and exposure and also to greater chronic individual stress, which alters the allostatic load of the maternal immune system. In turn, this leads to adverse outcomes in children, including increased susceptibility to air pollution.


title: Wildfire

text: Carbon monoxide (CO) is a colorless, odorless gas that can be found at the highest concentration at close proximity to a smoldering fire. For this reason, carbon monoxide inhalation is a serious threat to the health of wildfire firefighters. CO in smoke can be inhaled into the lungs where it is absorbed into the bloodstream and reduces oxygen delivery to the body's vital organs. At high concentrations, it can cause headaches, weakness, dizziness, confusion, nausea, disorientation, visual impairment, coma, and even death. However, even at lower concentrations, such as those found at wildfires, individuals with cardiovascular disease may experience chest pain and cardiac arrhythmia. A recent study tracking the number and cause of wildfire firefighter deaths from 1990–2006 found that 21.9% of the deaths occurred from heart attacks.


title: Wildfire

text: Another important and somewhat less obvious health effect of wildfires is psychiatric diseases and disorders. Both adults and children from countries ranging from the United States and Canada to Greece and Australia who were directly and indirectly affected by wildfires were found by researchers to demonstrate several different mental conditions linked to their experience with the wildfires. These include post-traumatic stress disorder (PTSD), depression, anxiety, and phobias.


title: Wildfire

text: The western US has seen an increase in both the frequency and intensity of wildfires over the last several decades. This increase has been attributed to the arid climate of the western US and the effects of global warming. An estimated 46 million people were exposed to wildfire smoke from 2004 to 2009 in the Western United States. Evidence has demonstrated that wildfire smoke can increase levels of particulate matter in the atmosphere.


title: Wildfire

text: The EPA has defined acceptable concentrations of particulate matter in the air, through the National Ambient Air Quality Standards and monitoring of ambient air quality has been mandated. Due to these monitoring programs and the incidence of several large wildfires near populated areas, epidemiological studies have been conducted and demonstrate an association between human health effects and an increase in fine particulate matter due to wildfire smoke.


title: Wildfire

text: The EPA has defined acceptable concentrations of particulate matter in the air. The National Ambient Air Quality Standards are part of the Clean Air Act and provide mandated guidelines for pollutant levels and the monitoring of ambient air quality. In addition to these monitoring programs, the increased incidence of wildfires near populated areas has precipitated several epidemiological studies. Such studies have demonstrated an association between negative human health effects and an increase in fine particulate matter due to wildfire smoke. The size of the particulate matter is significant as smaller particulate matter (fine) is easily inhaled into the human respiratory tract. Often, small particulate matter can be inhaled into deep lung tissue causing respiratory distress, illness, or disease.


title: Wildfire

text: An increase in PM smoke emitted from the Hayman fire in Colorado in June 2002, was associated with an increase in respiratory symptoms in patients with COPD. Looking at the wildfires in Southern California in October 2003 in a similar manner, investigators have shown an increase in hospital admissions due to asthma symptoms while being exposed to peak concentrations of PM in smoke. Another epidemiological study found a 7.2% (95% confidence interval: 0.25%, 15%) increase in risk of respiratory related hospital admissions during smoke wave days with high wildfire-specific particulate matter 2.5 compared to matched non-smoke-wave days.


title: Wildfire

text: Children participating in the Children's Health Study were also found to have an increase in eye and respiratory symptoms, medication use and physician visits. Recently, it was demonstrated that mothers who were pregnant during the fires gave birth to babies with a slightly reduced average birth weight compared to those who were not exposed to wildfire during birth. Suggesting that pregnant women may also be at greater risk to adverse effects from wildfire. Worldwide it is estimated that 339,000 people die due to the effects of wildfire smoke each year.


title: Wildfire

text: While the size of particulate matter is an important consideration for health effects, the chemical composition of particulate matter (PM) from wildfire smoke should also be considered. Antecedent studies have demonstrated that the chemical composition of PM from wildfire smoke can yield different estimates of human health outcomes as compared to other sources of smoke. health outcomes for people exposed to wildfire smoke may differ from those exposed to smoke from alternative sources such as solid fuels.


title: Wildfire

text: The first evidence of wildfires is fossils of the giant fungi Prototaxites preserved as charcoal, discovered in South Wales and Poland, dating to the Silurian period (about ). Smoldering surface fires started to occur sometime before the Early Devonian period . Low atmospheric oxygen during the Middle and Late Devonian was accompanied by a decrease in charcoal abundance. Additional charcoal evidence suggests that fires continued through the Carboniferous period. Later, the overall increase of atmospheric oxygen from 13% in the Late Devonian to 30–31% by the Late Permian was accompanied by a more widespread distribution of wildfires. Later, a decrease in wildfire-related charcoal deposits from the late Permian to the Triassic periods is explained by a decrease in oxygen levels.


title: Wildfire

text: Wildfires during the Paleozoic and Mesozoic periods followed patterns similar to fires that occur in modern times. Surface fires driven by dry seasons are evident in Devonian and Carboniferous progymnosperm forests. Lepidodendron forests dating to the Carboniferous period have charred peaks, evidence of crown fires. In Jurassic gymnosperm forests, there is evidence of high frequency, light surface fires. The increase of fire activity in the late Tertiary is possibly due to the increase of C-type grasses. As these grasses shifted to more mesic habitats, their high flammability increased fire frequency, promoting grasslands over woodlands. However, fire-prone habitats may have contributed to the prominence of trees such as those of the genera "Eucalyptus", "Pinus" and "Sequoia", which have thick bark to withstand fires and employ pyriscence.


title: Wildfire

text: The human use of fire for agricultural and hunting purposes during the Paleolithic and Mesolithic ages altered the preexisting landscapes and fire regimes. Woodlands were gradually replaced by smaller vegetation that facilitated travel, hunting, seed-gathering and planting. In recorded human history, minor allusions to wildfires were mentioned in the Bible and by 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. 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 Germany, regular burning was documented in 1290 in the Odenwald and in 1344 in the Black Forest. In the 14th century Sardinia, firebreaks were used for wildfire protection. In Spain during the 1550s, sheep husbandry was discouraged in certain provinces by Philip II due to the harmful effects of fires used in transhumance. As early as the 17th century, 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. In the post-World War II Baltic region, socio-economic changes led more stringent air quality standards and bans on fires that eliminated traditional burning practices. In the mid-19th century, explorers from observed Australian Aborigines using fire for ground clearing, hunting, and regeneration of plant food in a method later named fire-stick farming. Such careful use of fire has been employed for centuries in the lands protected by Kakadu National Park to encourage biodiversity.


title: Wildfire

text: 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. 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. 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. A meta-analysis found that 17 times more land burned annually in California before 1800 compared to recent decades (1,800,000 hectares/year compared to 102,000 hectares/year).


title: Wildfire

text: According to a paper published in the journal "Science", the number of natural and human-caused fires decreased by 24.3% between 1998 and 2015. Researchers explain this a transition from nomadism to settled lifestyle and intensification of agriculture that lead to a drop in the use of fire for land clearing.


title: Wildfire

text: Increases of certain tree species (i.e. conifers) over others (i.e. deciduous trees) can increase wildfire risk, especially if these trees are also planted in monocultures


title: Wildfire

text: Some invasive species, moved in by humans (i.e., for the pulp and paper industry) have in some cases also increased the intensity of wildfires. Examples include species such as Eucalyptus in California and gamba grass in Australia.


title: Wildfire

text: Wildfires have a place in many cultures. "To spread like wildfire" is a common idiom in English, meaning something that "quickly affects or becomes known by more and more people". The Smokey Bear fire prevention campaign has yielded one of the most popular characters in the United States; for many years there was a living Smokey Bear mascot, and it has been commemorated on postage stamps.


title: Wildfire

text: Wildfire activity has been attributed as a major factor in the development of Ancient Greece. In modern Greece, as in many other regions, it is the most common natural disaster and figures prominently in the social and economic lives of its people.


title: Wildfire

text: In regards to communicating information to the public regarding wildfire safety, some of the most effective ways to communicate with others about wildfires are community outreach conducted through presentations to homeowners and neighborhood associations, community events such as festivals and county fairs, and youth programs.


title: Liberty Media

text: Liberty Media Corporation (commonly referred to as Liberty Media or just Liberty) is an American mass media company controlled by chairman John C. Malone. The company has three divisions, reflecting the company's ownership stakes in Formula One, SiriusXM, and the Atlanta Braves Major League Baseball team.


title: Liberty Media

text: Liberty Media began in 1991 as a spin-off of TCI, an American cable-television group. Peter Barton, hired by TCI's Malone, served as president until retiring in April 1997. The company took over TCI assets considered to have little value, but Barton completed "a deal every ten days for six years" and made the company a big success. Liberty was merged back into TCI in the mid-1990s.


title: Liberty Media

text: On March 13, 1998, Liberty Media Group and TCI Group announced the merger of Encore and STARZ! into a single company—Encore Media Group, owned by Liberty. Encore was taking advantage of the growth of digital cable, while TCI, which had previously owned twenty percent of Encore, was more interested in traditional cable.


title: Liberty Media

text: After U.S. Department of Justice approval that required TCI to sell its 23.5% interest in Sprint Corporation PSC, TCI was acquired by AT&T on March 9, 1999 for approximately $48 billion. Liberty Media merged with TCI Ventures Group LLC (TCIVA), TCI's telephone and Internet businesses, and the resulting company became part of AT&T, giving Liberty Media $5.5 billion to repurchase stock or buy other companies.


title: Liberty Media

text: AT&T bought the other TCI businesses—@Home Corp., National Digital Television Center and Western Tele-Communications Inc.—for $2.5 billion in cash. TCI chairman Malone, who became head of the new company, said buyers would not want all of TCI, but they would be interested in Liberty Media. Malone wanted to start a finance unit similar to GE Capital, which could start new cable or Internet services. TCI had already planned digital cable set-top boxes.


title: Liberty Media

text: On September 28, 1998, Liberty Media announced the formation of Liberty Interactive, a company which would take advantage of new technologies such as set-top boxes to develop interactive programming. The company would own 86% of TCI Music Inc. (NASDAQ symbol: TUNE/TUNEP). As of January 1, 1999, E! Entertainment President and chief executive officer Lee Masters would become the new company's CEO, and Bruce Ravenel would be Chief Technology Officer.


title: Liberty Media

text: On September 10, 1999, Liberty Media Group renamed TCI Music to Liberty Digital Inc. (NASDAQ symbol: LDIG), with the new company trading on NASDAQ's National Market tier, after Liberty Media traded most of its Internet content, interactive television assets, and rights to provide AT&T's cable systems with interactive services, in addition to cash and notes valued at $150 million, for TCI Music stock. Masters, who became Liberty Digital's CEO, told "The Wall Street Journal" that the new company had a value of $1 billion, $650 million of that from the interactive unit of Liberty Media, which had also used the name Liberty Digital. Liberty Digital lost $244 million with revenue of $66 million in 1999, thanks to investments in struggling Internet businesses homegrocer.com, drugstore.com, TiVo and iVillage. The company bought half of the Game Show Network because of its interactive features.


title: Liberty Media

text: On December 17, 1999, TCI Satellite Entertainment Inc. (TSAT), based in Englewood, Colorado, announced that Liberty Media was trading its interest in Sprint PCS for $300 million in TCI Satellite preferred stock. A new company, 90% owned by Liberty Media and 10% owned by TCI Satellite, would combine the satellite-related businesses and take advantage of the growing area of Internet content. Liberty Media president and CEO Robert R. Bennett said the deal would benefit stockholders of both companies.


title: Liberty Media

text: Another new company was Liberty Livewire, formed from Todd-AO and two other companies by Liberty Media, which provided audio and video post-production services. David Beddow of TCI became CEO.


title: Liberty Media

text: Liberty Media's Discovery Channel and QVC continued to do well, but the newer projects had problems and the company's stock price dropped by half. If AT&T agreed to spin off Liberty Media, new deals such as a possible News Corp. purchase of DirecTV would be easier because AT&T would no longer require federal approval to complete such deals. Liberty Media was spun off from AT&T on August 10, 2001. This was one of three possible actions to ensure federal approval of AT&T's $54 billion acquisition of MediaOne Group—the others were selling its 25.5% share of Time Warner Entertainment and dropping 11.8 million cable customers.


title: Liberty Media

text: Also in 2001, Liberty Media acquired the remainder of Liberty Digital and Liberty Satellite & Technology (formerly TCI Satellite). Both companies were independent spinoffs of TCI, though Liberty already owned 90% of both companies after the exchange for Sprint PCS stock. Being independent increased their asset values, but the stock prices of both dropped, negating any benefits.


title: Liberty Media

text: Liberty Media subsequently spent $5 billion on nine German regional cable networks. Apart from television distribution it held major interests in other groups. For example, it was the largest shareholder in News Corporation (though the founding Murdoch family owns more voting shares), and had a 4% stake in Time Warner.


title: Liberty Media

text: On May 16, 2006, IDT sold its IDT Entertainment division to Liberty Media "for all of Liberty Media's interests in IDT, $186 million in cash and the assumption of existing indebtedness". IDT Entertainment's assets and Starz Entertainment Group's line of premium television channels combined to produce content for all distribution platforms.


title: Liberty Media

text: Liberty negotiated an asset swap with News Corp. and Time Warner that would give it control of DirecTV and the Atlanta Braves baseball team. On February 12, 2007, the deal was completed with Time Warner wherein Liberty would receive the Atlanta Braves and a group of craft magazines, along with $1 billion in cash in exchange for 60 million shares of Time Warner stock (valued at $1.27 billion as of market close on February 12, 2007). The deal was approved by Major League Baseball and then completed on May 16, 2007. On February 20, 2008, the Federal Communications Commission approved the exchange of 16.3% of News Corp. for 38.4% of DirecTV, an $11 billion deal that also gave Liberty sports networks in Denver, Pittsburgh and Seattle plus $550 million in cash.


title: Liberty Media

text: In April 2007, Liberty completed a purchase of Green Bay, Wisconsin, television station WFRV-TV, and satellite station WJMN-TV in Escanaba, Michigan, which serves the Marquette, Michigan, market. The deal was part of a swap of 7.59 million shares of common stock in CBS, the stations' owner, that was held by Liberty Media; in exchange for the stock, CBS gave Liberty the stations and $170 million in cash. Liberty announced plans in April 2011 to sell WFRV and WJMN to Nexstar Broadcasting Group for $20 million.


title: Liberty Media

text: On February 17, 2009, Liberty announced that it would invest up to $530 million into the struggling Sirius XM Radio Inc., in a structured deal that would help the satellite radio provider avoid filing bankruptcy protection by meeting its obligations. The deal provided two board seats for Liberty Media, and provided cash for operations and development, with a maturity date of December 2012 for the loan. On March 6, the two companies approved the second part of the deal, with Sirius XM getting $250 million immediately and Liberty receiving 12.5 million shares of preferred stock convertible into a 40% ownership of Sirius XM common stock.


title: Liberty Media

text: In 2010, Liberty Media announced that it would spin off Liberty Starz and Liberty Capital and keep Liberty Interactive. The spinoff took the name Liberty CapStarz, but renamed itself Liberty Media in 2011.


title: Liberty Media

text: On the Fortune 500 list 2011, Liberty Media was ranked 224, moving up from 2010 when they were ranked 227.


title: Liberty Media

text: In May 2011, Liberty announced it was in talks to buy the Barnes & Noble bookstore chain for $1.02 billion. It eventually bought a 16% stake in the form of preferred stock in Barnes & Noble for $204 million.


title: Liberty Media

text: On August 8, 2012, Liberty Media announced that it would spin off Starz into a separate publicly traded company. The spin-off of Starz Inc. was completed on January 15, 2013.


title: Liberty Media

text: The company agreed in March 2013 to pay $2.62 billion for 27.3% of Charter Communications from Apollo Global Management, Oaktree Capital Management and Crestview Partners with the provision that Liberty would not increase its stake past 35% until after January 2016 but no more than 39.99%. By May 1, Liberty completed the transaction and placed four directors on Charter's board.


title: Liberty Media

text: In 2014, Liberty Media spun off TruePosition and its holdings in Charter Communications into a new company, Liberty Broadband.


title: Liberty Media

text: In late 2016, Liberty Media agreed to buy the Formula One Group for US$4.4 billion (£3.3 billion). The deal was finalized in January 2017 for a total of US$4.6 billion (£3.44 billion).


title: Liberty Media

text: On November 17, 2022, Liberty Media announced that it would spilt off the Atlanta Braves and its associated real estate development project and the creation of a new Liberty Live Group tracking stock.


title: Liberty Media

text: Liberty has issued tracking stocks for each of the 3 divisions, and each tracking stock is in 3 different series (A, B and C) having different voting rights, meaning that the company's common stock trades under nine different stock symbols. Seven of the nine are listed on the Nasdaq stock market and two trade over the counter.


title: Liberty Media

text: On September 3, 2008, Liberty Media decided to initiate the process of spinning off Liberty Entertainment to Liberty Media shareholders, leaving Malone with a majority ownership of the new company. On May 4, 2009, The DirecTV Group Inc. said it would become a part of Liberty's entertainment unit, part of which would then be spun off as a separate company called DirecTV. The new company would also acquire Liberty's one hundred percent interests in the three FSN networks and its 50% interest in GSN. The rest of the unit would be traded as Liberty Starz. Liberty would increase its share of DirecTV from 48 to 54%, with Malone and his family owning 24%.


title: Liberty Media

text: On May 4, 2009, Liberty announced that it would split off Liberty Entertainment, Inc., a subsidiary owning the three Fox Sports Net (FSN) channels (now Root Sports) acquired under the swap with News Corp. and Liberty's 65% interest in GSN, into a separate company that would merge with The DirecTV Group, reducing Liberty owner John Malone's stake in DirecTV to 24%. The merger was completed on November 19, 2009, with The DirecTV Group and Liberty Entertainment becoming subsidiaries of a new company named DirecTV.


title: Liberty Media

text: On June 16, 2010, Malone exchanged his preferred stock in DirecTV with equivalent amounts of common stock, reducing his voting interest in the company from 24% to 3%, with Malone resigning as chairman and ending his managerial role at DirecTV.


title: Northwest Passage

text: The Northwest Passage (NWP) is the sea route between the Atlantic and Pacific oceans through the Arctic Ocean, along the northern coast of North America via waterways through the Canadian Arctic Archipelago. The eastern route along the Arctic coasts of Norway and Siberia is accordingly called the Northeast Passage (NEP).


title: Northwest Passage

text: The various islands of the archipelago are separated from one another and from Mainland Canada by a series of Arctic waterways collectively known as the Northwest Passages, Northwestern Passages or the Canadian Internal Waters.


title: Northwest Passage

text: For centuries, European explorers, beginning with Christopher Columbus in 1492, sought a navigable passage as a possible trade route to Asia, but were blocked by North, Central, and South America, by ice, or by rough waters (e.g. Tierra del Fuego). An ice-bound northern route was discovered in 1850 by the Irish explorer Robert McClure. Scotsman John Rae explored a more southerly area in 1854 through which Norwegian Roald Amundsen found a route, making the first complete passage in 1903–1906. Until 2009, the Arctic pack ice prevented regular marine shipping throughout most of the year. Arctic sea ice decline, linked primarily to climate change, has rendered the waterways more navigable for ice navigation.


title: Northwest Passage

text: The contested sovereignty claims over the waters may complicate future shipping through the region: the Canadian government maintains that the Northwestern Passages are part of Canadian Internal Waters, but the United States and various European countries claim that they are an international strait and transit passage, allowing free and unencumbered passage. If, as has been claimed, parts of the eastern end of the Passage are barely deep, the route's viability as a Euro-Asian shipping route is reduced. In 2016, a Chinese shipping line expressed a desire to make regular voyages of cargo ships using the passage to the Eastern United States and Europe, after a successful passage by "Nordic Orion" of 73,500 tonnes deadweight tonnage in September 2013. Fully loaded, "Nordic Orion" sat too deep in the water to sail through the Panama Canal.


title: Northwest Passage

text: Before the Little Ice Age (late Middle Ages to the 19th century), Norwegian Vikings sailed as far north and west as Ellesmere Island, Skraeling Island and Ruin Island for hunting expeditions and trading with the Inuit and people of the Dorset culture who already inhabited the region. Between the end of the 15th century and the 20th century, colonial powers from Europe dispatched explorers in an attempt to discover a commercial sea route north and west around North America. The Northwest Passage represented a new route to the established trading nations of Asia.


title: Northwest Passage

text: England called the hypothetical northern route the "Northwest Passage". The desire to establish such a route motivated much of the European exploration of both coasts of North America, also known as the New World. When it became apparent that there was no route through the heart of the continent, attention turned to the possibility of a passage through northern waters. There was a lack of scientific knowledge about conditions; for instance, some people believed that seawater was incapable of freezing. (As late as the mid-18th century, Captain James Cook had reported that Antarctic icebergs had yielded fresh water, seemingly confirming the hypothesis.) Explorers thought that an open water route close to the North Pole must exist. The belief that a route lay to the far north persisted for several centuries and led to numerous expeditions into the Arctic. Many ended in disaster, including that by Sir John Franklin in 1845. While searching for him the McClure Arctic Expedition discovered the Northwest Passage in 1850.


title: Northwest Passage

text: In 1906, the Norwegian explorer Roald Amundsen was the first to complete the passage solely by ship, from Greenland to Alaska in the sloop . Since that date, several fortified ships have made the journey.


title: Northwest Passage

text: From east to west, the direction of most early exploration attempts, expeditions entered the passage from the Atlantic Ocean via the Davis Strait and through Baffin Bay, both of which are in Canada. Five to seven routes have been taken through the Canadian Arctic Archipelago, via the McClure Strait, Dease Strait, and the Prince of Wales Strait, but not all of them are suitable for larger ships. From there ships passed through westward through the Beaufort Sea and the Chukchi Sea, and then southwards through the Bering Strait (separating Russia and Alaska), into the Pacific Ocean.


title: Northwest Passage

text: In the 21st century, major changes to the ice pack due to climate change have stirred speculation that the passage may become clear enough of ice to permit safe commercial shipping for at least part of the year. On August 21, 2007, the Northwest Passage became open to ships without the need of an icebreaker. According to Nalan Koc of the Norwegian Polar Institute, this was the first time the Passage has been clear since they began keeping records in 1972. The Northwest Passage opened again on August 25, 2008. It is usually reported in mainstream media that ocean thawing will open up the Northwest Passage (and the Northern Sea Route) for various kind of ships, making it possible to sail around the Arctic ice cap and possibly cutting thousands of miles off shipping routes. Warning that the NASA satellite images suggested that the Arctic had entered a "death spiral" caused by climate change, Professor Mark Serreze, a sea ice specialist at the U.S. National Snow and Ice Data Center (NSIDC) said: "The passages are open. It's a historic event. We are going to see this more and more as the years go by."


title: Northwest Passage

text: However, some thick sections of ice will remain hard to melt in the shorter term. Drifting and persistence of large chunks of ice, especially in springtime, can be problematic as they can clog entire straits or severely damage a ship's hull. Cargo routes may thus be slow and uncertain, depending on prevailing conditions and the ability to predict them. Because much containerized traffic operates in a just-in-time mode (which does not tolerate delays well) and because of the relative isolation of the passage (which impedes shipping companies from optimizing their operations by grouping multiple stopovers on the same itinerary), the Northwest Passage and other Arctic routes are not always seen as promising shipping lanes by industry insiders, at least for the time being. The uncertainty related to physical damage to ships is also thought to translate into higher insurance premiums, especially because of the technical challenges posed by Arctic navigation (as of 2014, only 12 percent of Canada's Arctic waters have been charted to modern standards).


title: Northwest Passage

text: The Beluga group of Bremen, Germany, sent the first Western commercial vessels through the Northern Sea Route (Northeast Passage) in 2009. Canada's Prime Minister Stephen Harper announced that "ships entering the North-West passage should first report to his government".


title: Northwest Passage

text: The first commercial cargo ship to have sailed through the Northwest Passage was in August 1969. SS "Manhattan", of 115,000 deadweight tonnage, was the largest commercial vessel ever to navigate the Northwest Passage.


title: Northwest Passage

text: The largest passenger ship to navigate the Northwest Passage was the cruise liner of gross tonnage 69,000. Starting on August 10, 2016, the ship sailed from Vancouver to New York City with 1,500 passengers and crew, taking 28 days.


title: Northwest Passage

text: In 2018, two of the freighters leaving Baffinland's port in the Milne Inlet, on Baffin Island's north shore, were bound for ports in Asia. Those freighters did not sail west through the remainder of the Northwest Passage, they sailed east, rounded the tip of Greenland, and transitted Russia's Northern Sea Route.


title: Northwest Passage

text: Many attempts were made to find a salt water exit west from Hudson Bay, but the Fury and Hecla Strait in the far north is blocked by ice. The eastern entrance and main axis of the northwest passage, the Parry Channel, was found in 1819. The approach from the west through Bering Strait is impractical because of the need to sail around ice near Point Barrow. East of Point Barrow the coast is fairly clear in summer. This area was mapped in pieces from overland in 1821–1839. This leaves the large rectangle north of the coast, south of Parry Channel and east of Baffin Island. This area was mostly mapped in 1848–1854 by ships looking for Franklin's lost expedition. The first crossing was made by Amundsen in 1903–1906. He used a small ship and hugged the coast.


title: Northwest Passage

text: The International Hydrographic Organization defines the limits of the Northwestern Passages as follows:


title: Northwest Passage

text: As a result of their westward explorations and their settlement of Greenland, the Vikings sailed as far north and west as Ellesmere Island, Skraeling Island for hunting expeditions and trading with Inuit groups. The subsequent arrival of the Little Ice Age is thought to have been one of the reasons that European seafaring into the Northwest Passage ceased until the late 15th century.


title: Northwest Passage

text: In 1539, Hernán Cortés commissioned Francisco de Ulloa to sail along the Baja California Peninsula on the western coast of North America. Ulloa concluded that the Gulf of California was the southernmost section of a strait supposedly linking the Pacific with the Gulf of Saint Lawrence. His voyage perpetuated the notion of the Island of California and saw the beginning of a search for the Strait of Anián.


title: Northwest Passage

text: The strait probably took its name from Ania, a Chinese province mentioned in a 1559 edition of Marco Polo's book; it first appears on a map issued by Italian cartographer Giacomo Gastaldi about 1562. Five years later Bolognino Zaltieri issued a map showing a narrow and crooked Strait of Anian separating Asia from the Americas. The strait grew in European imagination as an easy sea lane linking Europe with the residence of Khagan (the Great Khan) in Cathay (northern China).


title: Northwest Passage

text: Cartographers and seamen tried to demonstrate its reality. Sir Francis Drake sought the western entrance in 1579. The Greek pilot Juan de Fuca, sailing from Acapulco (in Mexico) under the flag of the Spanish crown, claimed he had sailed the strait from the Pacific to the North Sea and back in 1592. The Spaniard Bartholomew de Fonte claimed to have sailed from Hudson Bay to the Pacific via the strait in 1640.


title: Northwest Passage

text: The first recorded attempt to discover the Northwest Passage was the east–west voyage of John Cabot in 1497, sent by Henry VII in search of a direct route to the Orient. In 1524, Charles V sent Estêvão Gomes to find a northern Atlantic passage to the Spice Islands. An English expedition was launched in 1576 by Martin Frobisher, who took three trips west to what is now the Canadian Arctic in order to find the passage. Frobisher Bay, which he first charted, is named after him.


title: Northwest Passage

text: As part of another expedition, in July 1583 Sir Humphrey Gilbert, who had written a treatise on the discovery of the passage and was a backer of Frobisher, claimed the territory of Newfoundland for the English crown. On August 8, 1585, the English explorer John Davis entered Cumberland Sound, Baffin Island.


title: Northwest Passage

text: The major rivers on the east coast were also explored in case they could lead to a transcontinental passage. Jacques Cartier's explorations of the Saint Lawrence River in 1535 were initiated in hope of finding a way through the continent. Cartier became persuaded that the St. Lawrence was the Passage; when he found the way blocked by rapids at what is now Montreal, he was so certain that these rapids were all that was keeping him from China (in French, "la Chine"), that he named the rapids for China. Samuel de Champlain renamed them Sault Saint-Louis in 1611, but the name was changed to Lachine Rapids in the mid-19th century.


title: Northwest Passage

text: In 1602, George Weymouth became the first European to explore what would later be called Hudson Strait when he sailed into the Strait. Weymouth's expedition to find the Northwest Passage was funded jointly by the British East India Company and the Muscovy Company. "Discovery" was the same ship used by Henry Hudson on his final voyage.


title: Northwest Passage

text: John Knight, employed by the British East India Company and the Muscovy Company, set out in 1606 to follow up on Weymouth's discoveries and find the Northwest Passage. After his ship ran aground and was nearly crushed by ice, Knight disappeared while searching for a better anchorage.


title: Northwest Passage

text: In 1609, Henry Hudson sailed up what is now called the Hudson River in search of the Passage; encouraged by the saltiness of the water in the estuary, he reached present-day Albany, New York, before giving up. On September 14, 1609, Hudson entered the Tappan Zee while sailing upstream from New York Harbor. At first, Hudson believed the widening of the river indicated that he had found the Northwest Passage. He proceeded upstream as far as present-day Troy before concluding that no such strait existed there. He later explored the Arctic and Hudson Bay.


title: Northwest Passage

text: In 1611, while in James Bay, Hudson's crew mutinied. They set Hudson and his teenage son John, along with seven sick, infirm, or loyal crewmen, adrift in a small open boat. He was never seen again.


title: Northwest Passage

text: A mission was sent out in 1612, again in "Discovery", commanded by Sir Thomas Button to find Henry Hudson and continue through the Northwest Passage. After failing to find Hudson, and exploring the west coast of Hudson Bay, Button returned home due to illness in the crew. In 1614, William Gibbons attempted to find the Passage, but was turned back by ice. The next year, 1615, Robert Bylot, a survivor of Hudson's crew, returned to Hudson Strait in "Discovery", but was turned back by ice. Bylot tried again in 1616 with William Baffin. They sailed as far as Lancaster Sound and reached 77°45′ North latitude, a record which stood for 236 years, before being blocked by ice.


title: Northwest Passage

text: On May 9, 1619, under the auspices of King Christian IV of Denmark–Norway, Jens Munk set out with 65 men and the king's two ships, "Einhörningen" (Unicorn), a small frigate, and "Lamprenen" (Lamprey), a sloop, which were outfitted under his own supervision. His mission was to discover the Northwest Passage to the Indies and China. Munk penetrated Davis Strait as far north as 69°, found Frobisher Bay, and then spent almost a month fighting his way through Hudson Strait. In September 1619, he found the entrance to Hudson Bay and spent the winter near the mouth of the Churchill River. Cold, famine, and scurvy destroyed so many of his men that only he and two other men survived. With these men, he sailed for home with "Lamprey" on July 16, 1620, reaching Bergen, Norway, on September 20, 1620.


title: Northwest Passage

text: René-Robert Cavelier, Sieur de La Salle built the sailing ship, , in his quest to find the Northwest Passage via the upper Great Lakes. He made his way across Lake Erie and Lake Huron, making port on Mackinac Island before landing at Washington Island at the mouth of Green Bay to trade for furs with Pottawatomie Indians. La Salle stayed behind while the ship sailed back to Mackinac with the furs. "Le Griffon" disappeared in 1679 on the return trip of her maiden voyage. In the spring of 1682, La Salle made his famous voyage down the Mississippi River to the Gulf of Mexico. La Salle led an expedition from France in 1684 to establish a French colony on the Gulf of Mexico. He was murdered by his followers in 1687.


title: Northwest Passage

text: Henry Ellis, born in Ireland, was part of a company aiming to discover the Northwest Passage in May 1746. After the difficult extinction of a fire on board the ship, he sailed to Greenland, where he traded goods with the Inuit peoples on July 8, 1746. He crossed to the town of Fort Nelson and spent the summer on the Hayes River. He renewed his efforts in June 1747, without success, before returning to England.


title: Northwest Passage

text: In 1772, the English fur trader Samuel Hearne travelled overland northwest from Hudson Bay to the Arctic Ocean, thereby proving that there was no strait connecting Hudson Bay to the Pacific Ocean.


title: Northwest Passage

text: Most Northwest Passage expeditions originated in Europe or on the east coast of North America, seeking to traverse the Passage in the westbound direction. Some progress was made in exploring the western reaches of the imagined passage.


title: Northwest Passage

text: In 1728 Vitus Bering, a Danish Navy officer in Russian service, used the strait first discovered by Semyon Dezhnyov in 1648 but later accredited to and named after Bering (the Bering Strait). He concluded that North America and Russia were separate land masses by sailing between them. In 1741 with Lieutenant Aleksei Chirikov, he explored seeking further lands beyond Siberia. While they were separated, Chirikov discovered several of the Aleutian Islands while Bering charted the Alaskan region. His ship was wrecked off the Kamchatka Peninsula, as many of his crew were disabled by scurvy.


title: Northwest Passage

text: The Spanish made several voyages to the northwest coast of North America during the late 18th century. Determining whether a Northwest Passage existed was one of the motives for their efforts. Among the voyages that involved careful searches for a Passage included the 1775 and 1779 voyages of Juan Francisco de la Bodega y Quadra. The journal of Francisco Antonio Mourelle, who served as Quadra's second in command in 1775, fell into English hands. It was translated and published in London, stimulating exploration.


title: Northwest Passage

text: Captain James Cook made use of the journal during his explorations of the region. In 1791 Alessandro Malaspina sailed to Yakutat Bay, Alaska, which was rumoured to be a Passage. In 1790 and 1791 Francisco de Eliza led several exploring voyages into the Strait of Juan de Fuca, searching for a possible Northwest Passage and finding the Strait of Georgia. To fully explore this new inland sea, an expedition under Dionisio Alcalá Galiano was sent in 1792. He was explicitly ordered to explore all channels that might turn out to be a Northwest Passage.


title: Northwest Passage

text: In 1776, Captain James Cook was dispatched by the Admiralty in Great Britain on an expedition to explore the Passage. A 1745 act, when extended in 1775, promised a £20,000 prize for whoever discovered the passage. Initially the Admiralty had wanted Charles Clerke to lead the expedition, with Cook (in retirement following his exploits in the Pacific) acting as a consultant. However, Cook had researched Bering's expeditions, and the Admiralty ultimately placed their faith in the veteran explorer to lead, with Clerke accompanying him.


title: Northwest Passage

text: After journeying through the Pacific, to make an attempt from the west, Cook began at Nootka Sound in April 1778. He headed north along the coastline, charting the lands and searching for the regions sailed by the Russians 40 years previously. The Admiralty's orders had commanded the expedition to ignore all inlets and rivers until they reached a latitude of 65°N. Cook, however, failed to make any progress in sighting a Northwestern Passage.


title: Northwest Passage

text: Various officers on the expedition, including William Bligh, George Vancouver, and John Gore, thought the existence of a route was 'improbable'. Before reaching 65°N they found the coastline pushing them further south, but Gore convinced Cook to sail on into the Cook Inlet in the hope of finding the route. They continued to the limits of the Alaskan peninsula and the start of the chain of Aleutian Islands. Despite reaching 70°N, they encountered nothing but icebergs.


title: Northwest Passage

text: From 1792 to 1794, the Vancouver Expedition (led by George Vancouver who had previously accompanied Cook) surveyed in detail all the passages from the Northwest Coast. He confirmed that there was no such passage south of the Bering Strait. This conclusion was supported by the evidence of Alexander MacKenzie, who explored the Arctic and Pacific Oceans in 1793.


title: Northwest Passage

text: In the first half of the 19th century, some parts of the Northwest Passage (north of the Bering Strait) were explored separately by many expeditions, including those by John Ross, Elisha Kent Kane, William Edward Parry, and James Clark Ross; overland expeditions were also led by John Franklin, George Back, Peter Warren Dease, Thomas Simpson, and John Rae. In 1826 Frederick William Beechey explored the north coast of Alaska, discovering Point Barrow.


title: Northwest Passage

text: Sir Robert McClure was credited with the discovery of the Northwest Passage in 1851 when he looked across McClure Strait from Banks Island and viewed Melville Island. However, this strait was not navigable to ships at that time. The only usable route linking the entrances of Lancaster Sound and Dolphin and Union Strait was discovered by John Rae in 1854.


title: Northwest Passage

text: In 1845, a lavishly equipped two-ship expedition led by Sir John Franklin sailed to the Canadian Arctic to chart the last unknown swaths of the Northwest Passage. Confidence was high, as they estimated there was less than remaining of unexplored Arctic mainland coast. When the ships failed to return, relief expeditions and search parties explored the Canadian Arctic, which resulted in a thorough charting of the region, along with a possible passage. Many artifacts from the expedition were found over the next century and a half, including notes that the ships were ice-locked in 1846 near King William Island, about halfway through the passage, and unable to break free. Records showed Franklin died in 1847 and Captain Francis Rawdon Moira Crozier took over command. In 1848 the expedition abandoned the two ships and its members tried to escape south across the tundra by sledge. Although some of the crew may have survived into the early 1850s, no evidence has ever been found of any survivors. In 1853, explorer John Rae was told by local Inuit about the disastrous fate of Franklin's expedition, but his reports were not welcomed in Britain.


title: Northwest Passage

text: Starvation, exposure and scurvy all contributed to the men's deaths. In 1981 Owen Beattie, an anthropologist from the University of Alberta, examined remains from sites associated with the expedition. This led to further investigations and the examination of tissue and bone from the frozen bodies of three seamen, John Torrington, William Braine and John Hartnell, exhumed from the permafrost of Beechey Island. Laboratory tests revealed high concentrations of lead in all three (the expedition carried 8,000 tins of food sealed with a lead-based solder). Another researcher has suggested botulism caused deaths among crew members. Evidence from 1996, that confirms reports first made by John Rae in 1854 based on Inuit accounts, suggests that the last of the crew may have resorted to cannibalism of deceased members in an effort to survive.


title: Northwest Passage

text: During the search for Franklin, Commander Robert McClure and his crew in traversed the Northwest Passage from west to east in the years 1850 to 1854, partly by ship and partly by sledge. McClure started out from England in December 1849, sailed the Atlantic Ocean south to Cape Horn and entered the Pacific Ocean. He sailed the Pacific north and passed through the Bering Strait, turning east at that point and reaching Banks Island.


title: Northwest Passage

text: McClure's ship was trapped in the ice for three winters near Banks Island, at the western end of Viscount Melville Sound. Finally McClure and his crew—who were by that time dying of starvation—were found by searchers who had travelled by sledge over the ice from a ship of Sir Edward Belcher's expedition. They rescued McClure and his crew, returning with them to Belcher's ships, which had entered the Sound from the east. McClure and his crew returned to England in 1854 on one of Belcher's ships. They were the first people known to circumnavigate the Americas and to discover and transit the Northwest Passage, albeit by ship and by sledge over the ice. (Both McClure and his ship were found by a party from HMS "Resolute", one of Belcher's ships, so his sledge journey was relatively short.)


title: Northwest Passage

text: This was an astonishing feat for that day and age, and McClure was knighted and promoted in rank. (He was made rear-admiral in 1867.) Both he and his crew also shared £10,000 awarded them by the British Parliament. In July 2010 Canadian archaeologists found his ship, HMS "Investigator," fairly intact but sunk about below the surface.


title: Northwest Passage

text: The expeditions by Franklin and McClure were in the tradition of British exploration: well-funded ship expeditions using modern technology, and usually including British Naval personnel. By contrast, John Rae was an employee of the Hudson's Bay Company, which operated a far-flung trade network and drove exploration of the Canadian North. They adopted a pragmatic approach and tended to be land-based. While Franklin and McClure tried to explore the passage by sea, Rae explored by land. He used dog sleds and techniques of surviving in the environment which he had learned from the native Inuit. The Franklin and McClure expeditions each employed hundreds of personnel and multiple ships. John Rae's expeditions included fewer than ten people and succeeded. Rae was also the explorer with the best safety record, having lost only one man in years of traversing Arctic lands. In 1854, Rae returned to the cities with information from the Inuit about the disastrous fate of the Franklin expedition.