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.

Human actions, such as climate change causing hotter and drier weather, have made wildfires worse around the world. 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 naturally or because of human activity. Natural causes include lightning, volcanic eruptions, sparks from rocks falling, and spontaneous combustions.

Humans can cause wildfires by accident, arson, or by using fire to clear land, like slash-and-burn farming in the tropics during the dry season. Farther from the equator, tools that spark, such as chainsaws, and overhead power lines can also start fires.

Spread

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

Wildfires spread based on what can burn, how it is arranged, and the weather. The shape of the land, called topography, affects how plants grow and how fires move.

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.

Climate change effects

See also: Effects of climate change § Wildfires

Wildfires have become more common in recent decades. Climate change brings hotter, drier weather. This dryness makes plants easier to catch fire.

The 2023 Canadian wildfires burned more land than any year since 1983. Studies show that extreme fires happen more often now than before.

Warmer weather and less rain help wildfires start and spread. This can also make wildfire seasons last longer. Some places have fewer fires because there are fewer trees due to farming.

Wildfires release carbon dioxide and other gases into the air. These can harm the environment and health, even far from the fire. Wildfire smoke can cause health problems and cost money to handle. Wildfires have added to global carbon emissions for many years.

Prevention and mitigation

Wildfire prevention helps stop fires and makes them less serious. This includes keeping the air clean, protecting nature, and thinking about how people sometimes start fires. For example, many fires in Europe start because of human actions.

Countries around the world use different ways 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 small, safe fires are started to remove things that could feed a bigger fire later. These burns help keep forests healthy and support plants and animals.

In areas where fires happen often, buildings are made with materials that resist fire, 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 things that feed fires, some areas use animals like goat herds to eat plants that could catch fire. In Northern California, goats have been used to help keep communities safer from wildfires.

Detection

See also: Remote sensing

Finding wildfires quickly is important so we can stop them from getting bigger. In the past, people used tall towers to watch for fires and sent messages by phone, carrier pigeons, or special mirrors called heliographs. Now, we have better tools like satellites and airplanes that can see fires from very far away. These tools help us spot fires even at night and in places that are hard to reach.

Small areas with many trees or near towns can use tiny sensors. These sensors can tell us the temperature, how wet the air is, and if there is smoke. Large 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 the place and technology. In areas 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.

Impacts on the natural environment

Forests can suffer when fires occur, which sometimes leads to loss of trees and damage to the land. Wildfires affect the air we breathe. Fire smoke can rise high and travel far, bringing pollution. This smoke contains tiny particles that can hurt our health and add carbon dioxide to the air, changing 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. But when fires happen too often or become too strong, they can harm animals and plants. This can also allow unwanted plants to grow.

Wildfires can 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 carbon dioxide, which can warm the planet.

Impacts on humans

Wildfires can be dangerous for people. They happen when things like trees and grass catch fire and spread quickly. 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 bad for people who already have trouble breathing, like those with asthma. Even healthy people 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 found in South Wales and Poland. These fossils are very old, dating back about 430 million years. They show that wildfires have been part of Earth's history for a very long time.

Over millions of years, the amount of oxygen in the air changed. This change affected how often wildfires happened.

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

Today, changes in how we use land and changes in climate can affect how often wildfires happen. Some areas may see more intense fires because of the types of trees or plants there. Learning about the history of wildfires helps us take better care of forests and landscapes.

Society and culture

Wildfires have been important 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 happen often.