Wildfires 101: Everything You Need to Know

Tourists watch wildfires in Blue Mountains National Park, Australia
Tourists watch wildfires in Jamison Valley, Blue Mountains National Park, Australia. Andrew Merry / Moment / Getty Images
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What Are Wildfires? 

Wildfires, also commonly called forest fires or bushfires, are unplanned and uncontrolled fires burning in a vegetated landscape, such as a forest or grasslands. Many wildfires are sparked by human activity, such as campfires, or natural causes, like lightning. Dry conditions and prolonged droughts, which are becoming more frequent with climate change, exacerbate the risks of wildfires. Droughts, high winds, and other extreme weather are also making wildfires more common and more powerful, with larger blazes that burn for longer and expand across more land.

From 1998 to 2017, over 2,400 human deaths were attributed to both wildfires and volcanoes. Even when people can evacuate an affected area, they may lose their homes or businesses to the fires. Wildfires can also kill wildlife in the habitats that catch fire. Further, wildfires feed back into a loop, worsening climate change by releasing more carbon dioxide and fine particulate matter into the air.

Quick Facts About Wildfires

  • About 84% of wildfires in the U.S. are caused by human activity.
  • In just one year (based on 2021 numbers), global wildfires can release over 1.76 billion metric tons of carbon dioxide.
  • The largest set of wildfires in history are the Siberian Taiga Fires, which happened in Russia in 2003. The series of fires burned over 47 million acres of land.
  • Pollution from wildfires is attributed to over 33,510 premature deaths globally per year. 
  • The deadliest wildfire in recent history (since 1900) happened in Minnesota in 1918, killing 1,000.
  • Lightning is the biggest natural source of wildfires, and extreme lightning events are getting worse with climate change.
  • Forests need 2 to 4 years of recovery time after a wildfire for the soil to replenish before restoration efforts can begin.
  • Major wildfires can create their own severe weather, including fire tornadoes.
  • Fireproofed homes can reduce the risk of destruction from wildfire by 40%.
  • According to the European Space Agency, wildfires affect an estimated 4 million square kilometers globally per year.

What Causes Wildfires?

In order to burn, a spark requires fuel, heat and oxygen to become a wildfire. The fuel is the trees, grasses or other organic material of a landscape. The oxygen is available in the atmosphere, especially when there are high winds. The third component, heat, can come from a few different sources: fire or sparks from humans, heat from a lightning bolt or a volcanic eruption.

Human Activity

The No. 1 cause of wildfires is human activity. Even in some cases where nature causes an ignition, drought and other conditions related to human-caused climate change play a part. Unattended campfires and campfires set up in dry landscapes, burning of trash and other debris, malfunctions with powerlines and other equipment, arson, and even discarded cigarettes can also lead to wildfires.

Natural Causes

Natural causes make up only about 10% to 15% of wildfires, but they can still play an important role in starting these fires. Lightning is one of the primary natural causes of wildfires. Lightning currents with less voltage that last longer are called hot lightning. The prolonged hot lightning has longer contact with the landscape, possibly sparking a fire.

Volcanic eruptions can also lead to another natural disaster: wildfires. Hot lava that flows away from the volcano onto dry brush or into forested areas can trigger a wildfire if other conditions are right.

Wildfire Statistics and Trends 

Wildfires are a natural phenomenon that would occur even without added pressures from human activity and climate change. But with the climate crisis, environmental conditions necessary to fuel wildfires have become more frequent. As such, wildfires are becoming more frequent around the world, burning for longer periods of time and expanding over greater swaths of land. 

U.S. Wildfires by State

The western U.S. experiences many wildfires every year, but these fires are also becoming more common in other parts of the country. In 2020 alone, The Climate Reality Project reported that wildfires in California, Oregon and Washington burned over 4 million acres. For 2021, the National Oceanic and Atmospheric Administration (NOAA) shared that 7,139,713 acres burned from a total of 58,733 fires. Here are the biggest fires of 2021 per state.

California Wildfires

California has more wildfires than any other state in the U.S., and it saw several large fires in 2021. Cal Fire reported 8,835 incidents in 2021 and 2,568,948 estimated acres burned. The biggest fires of the year include: 

  • Dixie Fire: This fire occurred in July 2021 due to powerlines. It burned 963,309 acres in Butte, Plumas, Lassen Shasta and Tehama counties. It was the second largest wildfire in the state’s history.
  • Monument Fire: Caused by lightning, this fire also started in July in Trinity County. It burned 223,124 acres and was the 14th largest fire in California’s history.
  • Caldor Fire: The Caldor Fire, which happened in Alpine, Amador and El Dorado Counties, burned 221,835 acres. It was the third largest fire in California for 2021 and the 15th largest in state history. This fire started in August 2021, and a father and son were arrested under suspected “reckless arson.”
  • River Complex: Another lightning-related fire, the River Complex fire affected 199,343 acres in Siskiyou and Trinity Counties in July 2021.

While fire season is just beginning for 2022, the northern part of the state is already seeing a massive fire, the McKinney Fire, which has already burned over 52,000 acres at the time of writing.

Colorado Wildfires 

Since 2001, the 20 biggest wildfires in Colorado’s history have happened, with the three largest in state history occurring in 2020 alone. There have already been several large fires in Colorado for 2022. Without enough snowfall earlier in the year, the state is struggling with dry conditions that could become a new normal.

The Marshall Fire started in late December 2021, and has since been deemed the most destructive in Colorado’s history. This fire destroyed nearly 1,100 homes and killed two people.

Arizona Wildfires

Fire season is already off to a brutal start in Arizona, with the following fires burning just this summer: 

  • Pipeline Fire: Just north of Flagstaff, the Pipeline Fire burned 26,532 acres in June and July 2022.
  • Haywire Fire: Also in June and July 2022, the Haywire Fire burned 5,575 acres near Doney Park and was followed by warnings of potential storms and flooding.
  • Contreras Fire: This fire, which started by lightning in June 2022, burned over 29,482 acres in the Baboquivari Mountain range.
  • Tunnel Fire: The Tunnel Fire burned over 26,500 acres near Flagstaff. It started in April 2022 and was declared fully contained in June.

Texas Wildfires 

In Texas, most of the state has spent summer 2022 under drought conditions and burn bans due to increased fire risks, and there are already some major blazes occurring this year.

  • Blanket Fire: This fire, caused by a suspected burning car, has affected over 5,900 acres since it started in July.
  • Chalk Mountain Fire: Started July 18, this ongoing fire near Glen Rose has so far burned 6,746 acres and is moving toward more populated areas.
  • Big L Fire: The Big L Fire burned over 11,000 acres in March 2022. While containment was quick, the cause of the fire is still under investigation.
  • Canadian River Bottom Fire: This blaze burned nearly 40,000 acres in April this year, impacting Roberts and Hemphill Counties.
  • Eastland Complex: This large blaze in Eastland County burned 54,513 acres in March and April. While the cause is under investigation, the fuel sources include tall grasses, timber, and agricultural lands.

Oregon Wildfires

Oregon has seen nearly 1,000 acres burn in 2022 so far. In 2021, the state saw a total of 77 fires that burned 1,053,936 acres, a major increase compared to the 52,543 acres burned in 37 fires in 2020. Dry underbrush, timber, logging, dry conditions and high winds all contribute to major blazes in Oregon.

  • Middle Fork Complex: This fire near Oakridge, Oregon burned 30,928 acres in fall 2021.
  • Bootleg Fire: Located northeast of Klamath Falls, this major wildfire burned over 413,000 acres in summer 2021. The fire required more than 2,000 personnel to contain it.

Additional States Impacted

While there are certainly wildfire hotspots in the U.S., increasing temperatures and extended droughts are creating perfect wildfire conditions around the country. For instance, in April 2022, in New Mexico, two prescribed wildfires turned into uncontrolled blazes, burning over 341,000 acres and becoming the largest wildfire in state history.

In 2022, Alaska, Idaho, Arizona and Nevada have already experienced, and are still experiencing, large fires. PBS has reported there are already massive wildfires — including the Lime Complex Fire that has burned over 865,620 acres — some of which are in traditionally “fireproof” parts of Alaska, and peak fire season has yet to arrive.

General Global Trends 

Climate change brings increasing temperatures and drier conditions that can fuel wildfires around the world. Researchers expect significant increases in wildfire risks in the U.S., South America, central Asia, southern Europe, southern Africa and Australia from 2070 to 2100.

Even in the UK, typically considered a colder locale, experts are telling citizens to expect more wildfires in the near future as extreme heatwaves grip the nation. 

The expected increase in wildfires will bring with it more emissions and more forest loss, according to a recent study. As fire seasons become longer and more severe, forest loss due to wildfires is steadily increasing, with the highest losses occurring in boreal forests, which span Canada, China, Finland, Japan, Norway, Russia, Sweden and the U.S. 

You can track ongoing fires through NASA’s Global Fire Tracking tool.

Effects of Wildfires 

Wildfires have far-reaching impacts on every living thing, from plants and animals to humans. Aside from destroying habitats and human homes and putting public health at risk, these fires can also come with major pricetags that affect local economies.

Environmental & Wildlife Impacts

Fires have a direct impact on the land they burn. Fast-moving blazes fueled by timber or dry, tall grasses and high winds can quickly burn through wildlife habitats, leaving little to no time for animals to escape. While fires are natural and even essential for biodiversity in some forested regions, the increasing frequency and severity of these events is detrimental to the environment.

Habitat Loss

Fires burn through tall grasses, forests and other dry landscapes, burning through habitats and leaving thousands or even millions of different animals displaced. Plant-eating animals can also be left short on food, while those farther up the food chain may struggle to hunt as their usual prey have been displaced.

Wildlife Deaths

As fires burn across landscapes, they can kill wildlife. The most notable example of this happened in Australia in 2019 and 2020, when massive bushfires killed or displaced an estimated 3 billion animals. More than 60,000 koalas were killed in the fires, with more severely burned. Now, the species has officially been listed as endangered.

Air Pollution

Wildfires contribute significantly to air pollution. For those in affected areas, the plumes of smoke and blood-red skies are clear indicators of pollutants in the atmosphere. Wildfires emit particulate matter, carbon monoxide, polycyclic aromatic hydrocarbons and water vapor. Fires can also release 1.76 billion metric tons of carbon emissions a year globally, which can further exacerbate climate change while also threatening the health of humans and wildlife.

Human Health Impacts 

As of 2020, wildfires cause about 70 deaths per year, although as many as 266 people died from wildfires in 1997. Wildfires can also cause burns and other injuries and long-lasting impacts, like worsening the air quality for communities or contaminating local watersheds.

Air Quality

Smoke from wildfires releases PM2.5, fine particulate matter with a diameter of 2.5 micrometers or less, that worsens air quality. Further, humans can inhale these fine particles, which can then go into the lungs or bloodstream leading to lung and heart health concerns. The particles in wildfire smoke can also cause irritation and damage to the eyes, nose and throat, leading to respiratory complications.

Unfortunately, inhalation of particulate matter can be deadly. A global study from 2021 found that an average of about 33,510 deaths per year could be attributed to acute wildfire-related PM 2.5 exposure. 

Mental Health

Experiencing a natural disaster, like a wildfire, can have serious impacts on mental health. These events can lead to post-traumatic stress disorder (PTSD) and depression, especially when families lose loved ones and/or their homes due to fires.

Water Contamination

Where there’s smoke, there’s ash. Ash left behind from wildfires can impact local water supplies and communities’ drinking water. The U.S. Geological Survey (USGS) reported that 80% of fresh water resources in the U.S. originate on forested land. 

After a forest fire, ash and other debris can become runoff into local waterways, including lakes, reservoirs and wetlands. In Colorado alone, more than $26 million was spent on water treatments and related issues after two major wildfires.

Economic Impacts

Wildfires have detrimental impacts on the environment, from threatening public health to destroying habitats and contributing to biodiversity loss. But these fires have a financial impact to local economies, too.

According to the U.S. Department of Commerce, annual wildfires in the U.S. create an economic burden of an estimated $71.1 billion to $347.8 billion, with losses accounting for around $63.5 billion to $285 billion and costs accounting for $7.6 billion to $62.8 billion. In California, the most wildfire-prone state in the country, economic damages in 2018 alone were around $148.5 billion.

In the U.S. and abroad, countries must spend money on firefighting resources to contain wildfires and account for losses from the fires. But wildfires can have indirect economic impacts as well. Burned areas can affect tourism numbers, lower real estate values, and require money for rehabilitation and restoration.

What Can Be Done to Mitigate Wildfire Risks ?

Although Smokey the Bear says, “Only you can prevent wildfires,” it’s a collective effort that requires everyday people, governments, and corporations to work together to curb climate change and reduce the risk of fires.

Wildfire Prevention 

The ultimate way to prevent wildfires is to curb climate change that worsens the conditions that fuel more frequent and destructive blazes. But aside from that, the goal is to reduce human-caused wildfires, since this phenomenon is natural and even essential for forests.

  • Avoid activities that can cause sparks, smoke, or fires in fire-prone areas, especially during dry, hot, and windy conditions.
  • Don’t drive over or park on dry brush. The heat from the car exhaust and other car parts may start a fire, and the dry landscape acts as fuel.
  • Know how to properly use machinery or equipment, like lawn mowers, and use spark arresters when possible.
  • Avoid burning debris, instead focusing on composting as much as possible. If you do need to burn debris, keep piles no larger than 4-feet-by-4-feet, and don’t start fires in dry or windy conditions.
  • Before starting a campfire, check with the U.S. Forest Service, a Bureau of Land Management office or local officials for permits.
  • Make sure not to start a campfire when conditions could spread the fire, and keep a shovel and bucket of water close by to stifle the flames if needed.
  • Clear an area at least 10 feet around a campfire or debris fire, moving any potential sources of fuel, like leaves or logs.
  • Never leave a controlled fire unattended.
  • Extinguish fires fully by drowning the fire with water, stirring the burned area to combine the wet soil with any remaining embers. Use the back of your hand to carefully check that the area is damp and cool before leaving.

Wildfire Preparedness and Safety

An alarming new report finds that very few states in the U.S. require homeowners to invest in fireproofing, despite it being a relatively low-cost and important action to take to protect structures in a wildfire. Fireproofing a home can reduce the likelihood a wildfire destroys it by 40%.

And whether or not you own a home, you should know how to prepare for a wildfire event to keep yourself safe. In the event of a wildfire, you may need to evacuate and/or live without power for several days.

  • Make a “go kit” with at least three days’ worth of essential items, like food, water, clothing, and other supplies in a portable bag or container.
  • Keep at least two weeks’ worth of supplies and essentials at home in case you are without power.
  • Don’t forget to keep a locked or child- and pet-proof container with enough medications for one month.
  • Keep important files and records in fire-proof containers, and consider keeping copies in your go kit.
  • Create and practice an emergency evacuation plan with your family.
  • In your car and/or go kit, have a battery-powered radio to tune into official updates.
  • Have extra batteries, chargers, and or solar-powered chargers for your radio, phone, and devices to stay connected and informed.
  • Air pollution after wildfires is dangerous. Stay indoors as much as possible, and use air filters if you have power. Also, consider wearing an N-95 mask.
  • Evacuate, even if there isn’t an official evacuation notice, if you are concerned or feel in danger.
  • Do not return home until officials give the go-ahead.


Wildfires are worsening in many countries globally, including the U.S., and are expected to become more of an issue in places they weren’t previously, like in the UK. Australia is particularly vulnerable to increasing blazes, as are regions of boreal forests.

As a part of nature, wildfires do play an essential part in promoting biodiversity, but only when they occur at a natural rate. Human activity and climate change are spurring more intense and more frequent fires that contribute more emissions, feeding into a loop that worsens climate change. 

Air pollutants from wildfires worsen air quality, putting the health of wildlife and humans at risk and costing countries billions of dollars per year to contain the blazes and pay for damages. Wildfires can also kill off vulnerable wildlife, as is the case for endangered koalas in Australia that recently lost tens of thousands from the already low population, and injure and/or displace thousands more animals.

Ultimately, the goal is not to end wildfires. They are an essential part of many ecosystems, but the fact that they are getting bigger and are happening more frequently does more harm than good. Thankfully, it’s not too late to minimize the number of wildfires.

We can reduce the number of human-made wildfires by staying aware of ongoing weather conditions. When conditions are dry, hot, and windy, avoid any activities that could create a spark or spread smoke and flames. Even driving your car or mowing the lawn can start a fire, so be mindful during high fire risk conditions.

Human-caused or not, wildfires can be destructive. If you live in an area prone to fires, make sure you have a safety plan in place, with supplies ready to go if you need to evacuate or are left without power for long periods of time.

Wildfires are another part of our world, and they are only expected to worsen as the world grows hotter. While we can mitigate personal risks, working collectively with governments and corporations to slow climate change is the best way to minimize wildfire risks worldwide.

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