Wildfire

A wildfire, forest fire, or a bushfire is an unplanned and uncontrolled fire in an area of combustible vegetation. Some natural forest ecosystems depend on wildfire as part of their life cycle. Modern forest management sometimes uses planned burns to reduce the risk of big fires and help forests stay healthy. But sometimes, these planned burns can accidentally become real wildfires.

Wildfires happen more often in places like Siberia in Russia; California, Washington, Oregon, Texas, and Florida in the United States; British Columbia in Canada; and Australia. Areas with dry, warm weather or certain types of forests are especially likely to see wildfires. These fires can hurt people, damage homes near forests, and cost a lot of money to fix.

Human actions, such as climate change causing hotter and drier weather, changing how land is used, and trying to stop fires, have made wildfires worse around the world. Fires release carbon into the air, which can warm the planet even more, creating a cycle that makes fires more likely. Even though wildfires can be dangerous, some plants and animals actually need fire to grow and reproduce, showing that fire can be a natural part of the environment.

Ignition

Wildfires can start either naturally or because of human activity. Natural causes include lightning, volcanic eruptions, sparks from rocks falling, and spontaneous combustions.

Humans can cause wildfires through accidents, arson, or using fire to clear land, like slash-and-burn farming in the tropics during the dry season. In areas farther from the equator, common causes are tools that spark, such as chainsaws, and overhead power lines. While arson can start many fires, most wildfires are due to a mix of human activities and natural conditions.

Spread

See also: Surface-area-to-volume ratio § Fire spread

The spread of wildfires depends on what can burn, how it is arranged, and the weather. Things like the shape of the land, called topography, affect how plants grow and how fires spread.

There are different types of wildfires based on what they burn:

• Ground fires burn things under the soil like roots and leaves, often slowly over many days.
• Surface fires burn plants close to the ground and can move slowly unless the slope or wind makes them faster.
• Ladder fires burn plants that reach up toward trees, helping fires climb higher.
• Crown fires burn the tops of trees and other plants high up, which can spread quickly under the right conditions.

Physical properties

See also: Combustion, Fire control, Heat wave, and Firestorm

Wildfires happen when three things come together: something to start the fire, fuel like plants, and oxygen in the air. If the plants are too wet, they won’t catch fire easily. But when it’s dry, like during a drought, plants can catch fire quickly.

Wildfires can spread very fast, especially in places with lots of dry grass or trees. The fire can jump far ahead by sending sparks on the wind. Big wildfires can even create their own strong winds and spinning fires that look like small tornadoes.

Climate change effects

See also: Effects of climate change § Wildfires

Wildfire disasters have increased a lot in recent decades. Climate change makes heatwaves and droughts stronger, drying out plants that can catch fire easily.

The area burned in the 2023 Canadian wildfires was more than twice that of any year since 1983. A study from June 2024 found that extreme fires happened more than twice as often from 2003 to 2023.

Climate change creates weather that makes wildfires more likely. Warmer temperatures and less rain dry out plants, making them catch fire faster. This can also make the wildfire season longer. Even though the weather helps wildfires start, some places have fewer fires because land has been changed for farming, so there are fewer trees to burn.

Wildfires release a lot of carbon dioxide and other gases into the air. These emissions can hurt the environment and affect health far from where the fires burn. Wildfire smoke can cause health problems and has big economic costs. Wildfires have been a big part of global carbon emissions for over a hundred years.

Prevention and mitigation

Wildfire prevention helps reduce the chance of fires and makes them less severe. This includes managing air quality, protecting nature, and thinking about how people can cause fires — for example, about 95% of forest fires in Europe start because of human actions.

Countries around the world use different methods to prevent wildfires. One way is called wildland fire use, where natural fires are watched but allowed to burn. Another method is controlled burns, where safe, small fires are started to remove materials that could feed a bigger fire later. These burns also help keep forests healthy and support different kinds of plants and animals.

In areas where fires are common, buildings are made with fire-resistant materials, and spaces around homes are kept clear of things that could catch fire easily. Some places, like the Philippines, create wide paths called fire lines between forests and villages to stop fires from spreading.

To reduce fire fuels, some areas use animals like goat herds to eat plants that could catch fire. In Northern California, thousands of goats have been used to help keep communities safer from wildfires.

Detection

See also: Remote sensing

Detecting wildfires quickly is very important for fighting them. In the past, people used fire lookout towers and reported fires by telephone, carrier pigeons, or heliographs. Later, cameras and infrared scanning were used. Today, we have better tools like satellites and airplanes that can spot fires from far away. These tools help us see fires even at night and in hard-to-reach places.

Local areas with lots of trees or near towns can use small sensor networks. These sensors can measure temperature, humidity, and smoke. Bigger areas are watched using satellites and special cameras on planes or helicopters. These tools help us find fires faster and know where they are, even though sometimes clouds or other things can make it harder to see.

Suppression

Wildfire suppression uses different tools depending on where the fire is and how advanced the technology in that area is. In places with fewer resources, people might throw sand or beat the fire with sticks. In more advanced areas, firefighters use special planes and helicopters to drop water or fire retardants on the flames. Even with these tools, putting out every wildfire completely isn’t always possible. Most wildfires are stopped before they get too big, but some can be hard to control if the weather is very bad.

Fighting wildfires can be dangerous for the people working to stop them. The heat and smoke can make it hard to see and stay safe. Firefighters work hard to stay healthy and use safety measures to protect themselves while they fight these fierce fires.

Impacts on the natural environment

Forests can suffer when fires occur, which sometimes leads to loss of trees and damage to the land. Between 2007 and 2019, around 261 million hectares of land were affected by fires each year, with almost half of that area being forests.

Wildfires also affect the air we breathe. Fire smoke can rise high into the sky and travel far away, bringing pollution. This smoke contains tiny particles that can hurt our health and also add carbon dioxide to the air, which can change the climate.

Some places, like parts of Australia, Africa, and the United States, need occasional fires to stay healthy. These fires clear out dead plants and help new growth. However, when fires happen too often or become too strong, they can harm animals and plants that are not used to such intense heat. This can also allow unwanted plants to grow, which may burn even easier in the future.

Wildfires can also hurt water supplies by washing ash and chemicals into rivers and lakes. This can make water unsafe to drink until it is cleaned. In some places, fires have damaged forests that help hold soil in place, leading to floods.

In some areas, like the Amazon rainforest, fires are becoming more common due to human activities. This threatens the many plants and animals that live there and releases large amounts of carbon dioxide, which can warm the planet.

Impacts on humans

Wildfires can be a big danger to people. They happen when things that can burn, like trees and grass, catch fire and spread fast. These fires can harm people in many ways, especially by creating smoke that can make it hard to breathe.

The smoke from wildfires has tiny particles and chemicals that can get into our lungs. This can be very bad for people who already have trouble breathing, like those with asthma. Even people who are healthy can feel sick from the smoke, with symptoms like coughing and sore throats. After a wildfire, there can also be dangers from damaged water systems and buildings, which can make people sick if they drink the water or use the buildings.

Some groups of people are more at risk, like firefighters who work close to the fires and families who live near areas where wildfires happen often. It’s important for everyone to stay safe during wildfires by following safety rules and staying indoors if the air is bad outside.

History

Further information: Fossil record of fire

The earliest signs of wildfires come from fossils of giant fungi found in South Wales and Poland, dating back about 430 million years. These fossils show that wildfires have been part of Earth's history for a very long time. As the amount of oxygen in the atmosphere changed over millions of years, so did the frequency of wildfires.

Humans have used fire for thousands of years. Ancient people used fire to clear land for farming, to hunt animals, and even in battles. Different cultures, like Native Americans and Aboriginal Australians, used controlled burns to manage their lands carefully. These practices helped maintain healthy ecosystems.

Today, changes in land use and climate can affect how often wildfires happen. Some areas with certain types of trees or invasive plants may see more intense fires. Understanding the history of wildfires helps us manage forests and landscapes better.

Society and culture

Wildfires have played a role in many cultures. The phrase "to spread like wildfire" means something that quickly becomes known or affects many people.

Wildfires have influenced places like Ancient Greece. In the United States, President Franklin D. Roosevelt started a fire prevention campaign in 1937. This campaign featured popular characters like Smokey Bear, who helped teach people about fire safety. Wildfires can also affect everyday life, such as influencing insurance for homes in areas where wildfires are common.