Wildfires, also known as forest fires, brush fires or vegetation fires, spread quickly without control, engulfing forests, grasslands and other natural environments. These fires are among nature’s most powerful and destructive forces, capable of destroying entire landscapes, putting human lives at risk and damaging ecosystems and communities over the long term. The National Interagency Fire Center (NIFC) reported that an average of 56,580 wildfires burned in 2023, burning an area of 26,93,910 acres.
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The World Resources Institute (WRI) estimates that wildfires will burn approximately 12 million hectares of land in 2023, an area equivalent to Nicaragua.
You are watching: What Causes Wildfires? Understanding the Triggers and Factors
Source: World Resources Institute
This is a 24% increase from the previous record. In Canada, extreme wildfires are responsible for approximately two-thirds (65%) of tree cover lost to fires that year, making them particularly devastating. Additionally, more than a quarter (27%) of total global tree cover loss is caused by these fires.
As wildfires break out in Los Angeles and cause significant damage, it’s important to understand how these fires occur and what’s behind them.
How do wildfires start?
Wildfires are often started by a combination of natural forces and human activity. The reasons behind these devastating fires can be traced to natural phenomena and human negligence or intentionality.
Natural causes of wildfires
1. Lightning strike
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Lightning is one of the major and common natural sources of wildfires. According to MDPI, “Approximately two-thirds of wildfires in the United States are caused by lightning strikes.” These fires are common, especially in hot areas. Additionally, dry vegetation is particularly susceptible to catching fire during thunderstorms. Due to the extreme heat generated by a lightning strike, trees, grass, and shrubs can catch fire and quickly turn into wildfires.
2. Volcanic eruption
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Although less common, volcanic eruptions can also trigger wildfires. Lava flows, debris, and ash are so hot that they can burn surrounding vegetation. These fires can spread quickly, especially in areas with little vegetation or prolonged drought. For example, a volcanic eruption in Hawaii in 2018 sparked wildfires that burned hundreds of acres of forest area.
3. Sparks from falling rocks
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In dry, rocky terrain, friction caused by falling rocks or the collision of boulders can produce sparks. While this is a less common cause of wildfires, it can still ignite nearby dry grass and brush. Dry conditions in places like the Rockies and some desert areas can make this a potential risk.
4. Spontaneous combustion
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Organic materials such as dry leaves or hay can spontaneously ignite under certain conditions. When these materials accumulate in large amounts and heat up, especially in poorly ventilated areas, they can catch fire. Although rare, this phenomenon can occur in certain wetland or forest areas where organic matter has accumulated over time.
human-caused wildfires
According to the National Park Service, nearly 85% of wildfires worldwide are caused by human activity. These fires can occur due to negligence, reckless behavior, or intentional conduct.
1. Campfires and outdoor cooking
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One of the leading causes of wildfires is improperly extinguished campfires. In dry grass or brush, tiny embers left behind can easily catch fire and get out of control.
2.Cigarette butts
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Another common cause of wildfires are discarded cigarette butts. In dry conditions, the burning remains of cigarettes can easily ignite nearby vegetation. This is a common problem in places with high foot activity, such as parks and forests, especially during the summer months when vegetation is driest and flammable.
3. Arson
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A large proportion of wildfires are caused by intentional arson. The reasons for these arson incidents vary, such as financial gain, vandalism or land conflicts. Arson is sometimes used to illegally clear land for farming. According to FEMA, “arson is the leading cause of fires in the United States (267,000 fires per year) and the second leading cause of deaths (475 fires) and injuries (2,000 fires); arson causes $1.4 billion in property damage annually in the U.S. 15% of wildfires are caused by arson.”
4. Power cords and electrical equipment
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Damaged or downed power lines can ignite wildfires, especially if the winds are high. Faulty power lines were the cause of California’s 2018 Camp Fire, which went on to become the deadliest and most destructive wildfire in the state’s history. This is more likely to occur when vegetation is dry and winds are strong during extreme weather events.
5. Agricultural practices
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Wildfires can also be caused by specific agricultural techniques, such as burning crop residues or slash-and-burn farming. These occasionally uncontrolled fires have the potential to spread into adjacent grasslands or woodlands. The World Health Organization (WHO) claims that most wildfires in Southeast Asia and other places are caused by agricultural burning.
5. Fireworks and celebrations
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Fireworks and pyrotechnics used at celebrations can spark wildfires, especially in dry conditions. Using fireworks in drought or heat wave areas can increase the risk of fires. In 2020, several wildfires in the United States were linked to fireworks during Fourth of July celebrations.
How do wildfires spread?
Fuels, weather and geography are major factors that influence the intensity and speed of wildfires.
Fuel load: An important aspect of wildfire spread
One of the major factors that influence the intensity and spread of wildfires is fuel. The term “fuel load” describes the amount of flammable vegetation (such as hay, trees and shrubs) at a specific location. If there is more fuel, the fire will burn faster and more violently.
Fuel characteristics:
- Size and shape: Smaller materials, such as hay and twigs, ignite faster and burn faster than larger, denser logs. This is why you use kindling to start a fire—small twigs have a larger surface area relative to their volume, which makes them easier to light.
- Arrangement: Spacing between fuel sources is also important. When fuel is loosely arranged, it dries faster and ignites more easily. In contrast, densely packed fuel retains moisture and takes longer to heat.
- Moisture content: Dry fuels burn faster, which is why wildfires are more intense during periods of drought or heat. Wet fuel is more difficult to ignite, which can slow down the progress of the fire.
As a fire spreads, it heats the surrounding fuel, making it dry and easier to ignite. This cycle makes it more difficult to control the fire because it quickly consumes more material.
How does weather cause wildfires to spread?
Weather plays an important role in the development and spread of wildfires. Three key weather factors—temperature, wind, and humidity—are responsible for the intensity and progression of wildfires:
- Temperature: Warmer temperatures can dry out vegetation, making it easier for fires to start and spread. Wildfires tend to be more active during the hottest parts of the day, often peaking in the afternoon.
- Wind: Wind is one of the most important factors in wildfire behavior. It provides oxygen, dries fuel, and pushes the fire throughout the area. Winds can also create “fire twisters” (similar to tornadoes) that can throw burning debris great distances, starting new fires. Wind-driven wildfires spread up to 10 times faster than ambient wind speeds.
- Moisture: High humidity or precipitation can slow wildfires by increasing the moisture content in fuels, making them harder to ignite. Conversely, low humidity and dry conditions make wildfires more likely to occur and more severe.
Topography: Effects of Land Characteristics
The geography of land is another important and influencing factor in the spread of wildfires. Fires move uphill faster due to the natural upward flow of smoke and heat, preheating the fuel before igniting. Steeper slopes can cause fires to spread faster because the heat from the fire can dry out vegetation on the mountain.
Once a fire reaches the top of a slope, it can have a hard time moving down because the fuel isn’t preheated in the same way. However, strong winds can sometimes counteract this effect, causing fires to spread downward.
In summary, wildfires are a natural part of many ecosystems, but their increasing frequency and intensity are alarming. Both natural factors and human activities contribute to this phenomenon. By understanding these causes and taking preventive measures, we can mitigate the effects of wildfires and protect our environment, wildlife, and communities.
Source: https://dinhtienhoang.edu.vn
Category: Optical Illusion