In this photograph from July 2021, One World Trade Center (left) and other New York City buildings are shrouded by smoke and haze from wildfires in western North America.
Credit: © Bjoern Kils, New York Media Boat/Reuters/Alamy Images

Have you looked at the sun or moon low in the sky in the past few weeks? You may have noticed them take on hues of orange and red. A hazy film may have blurred out the horizon. These visual effects were caused by smoke and haze from fires in western North America, in what is shaping up to be another record wildfire season. So far this year, wildfires have scorched nearly 3 million acres (1.2 million hectares) in the United States alone.

The Dixie Fire is the largest in California, burning almost 250,000 acres (100,000 hectares). It began near where the deadly Camp Fire burned in 2018, killing more than 80 people. Both fires were sparked by equipment from the utility company Pacific Gas and Electric Co. (PG&E). This month, PG&E announced its intent to bury 10,000 miles (16,000 kilometers) of power lines in areas of the state most at risk for wildfires. The project—which PG&E had long resisted—is estimated to cost at least $15 billion.

California usually dominates the wildfire season. The largest fire of the season, however, belongs to Oregon. The Bootleg Fire started on July 6 and has burned more than 400,000 acres (160,000 hectares). The fire persevered through rain and continues to defy efforts to contain it.

The Bootleg Fire threatened Mitchell Monument, dedicated to the only civilians killed on U.S. soil during World War II (1939-1945). Toward the end of the war, Japan released more than 9,000 bomb-carrying balloons, intended to land on the West Coast of the United States. The bombs caused mostly minor damage. But one bomb killed five members of a picnicking family near Bly, Oregon. Firefighters battling the Bootleg blaze worked to save the forest around the monument, including trees damaged by the bomb blast.

Nearby Idaho and Montana also have dozens of fires. The Canadian province of British Columbia declared a state of emergency due to the hundreds of wildfires raging there. The government of Mexico sent firefighters to the province to assist. Outside North America, fires burned in Greece, Turkey, Russia, and Italy.

Smoke from the North American fires drifted east on the prevailing winds, reducing air quality across the continent. Air quality was affected as far away as New York City. The smoke threatened people with such medical conditions as asthma, chronic obstructive pulmonary disease (COPD), and heart disease.

Climatologists and other experts blame the severe fire outbreaks on the intense drought gripping the western half of the continent. In June, a sizzling heat wave killed hundreds of people in Oregon, Washington, and British Columbia. Experts strongly suspect the drought and heat were intensified by climate change.

Motorists stop to observe the Walbridge fire, part of the larger LNU Lightning Complex fire, from a vineyard in Healdsburg, California, on Aug. 20, 2020. A series of massive fires in northern and central California forced evacuations as flames quickly spread, darkening the skies and polluting the air.
Credit: © Josh Edelson, AFP/Getty Images

Wildfires have ravaged the U.S. state of California, killing at least 5 people and forcing thousands to evacuate (leave) their homes. Fueled by a heat wave and sparked by lightning strikes, the wildfires have set the state ablaze and covered the air in thick smoke.

Wildfire is the uncontrolled burning of large areas of vegetation. Wildfires may be ignited by human activities or by natural causes. Such natural causes include lightning, volcanic activity, or even intense sunlight. Wildfires occur on every continent except Antarctica. They are most common in the temperate forests and grasslands midway between the equator and the poles. They are less common in tropical and desert ecosystems.

These are far from California’s deadliest wildfires. Numerous major wildfires occurred in California in the early 2000′s. In 2003, wildfires in southern California destroyed thousands of homes and killed more than 20 people. In 2007, deadly wildfires forced the evacuation of about 500,000 people in San Diego County. In 2013, the so-called Rim Fire burned large areas of the Stanislaus National Forest near Yosemite National Park. Some of the largest wildfires in California history burned during the summer of 2018.

The unhealthy air quality caused by the wildfires is especially concerning, because of the pandemic (global outbreak) of the respiratory disease COVID-19. Smoke-polluted air can weaken lung function, reducing the body’s ability to fight infection.

The current round of fires was made worse by an intense heat wave baking the American Southwest. On August 16, temperatures in California’s Death Valley reached 130 °F (54.4 °C). If these measurements are confirmed, they would be the hottest surface air temperatures ever recorded on Earth.

October 4, 2019

Since the beginning of winter in South America (summer in the Northern Hemisphere), more than 200,000 wildfires have struck the Amazon rain forest of Brazil, Bolivia, Paraguay, Peru, and Venezuela. Some 30 million acres (12 million hectares) of wilderness have been lost in the fires, causing incalculable damage to the environment. The unusually severe fire season was blamed on winds and high temperatures as well as the ancestral practice of chaqueo (slash-and-burn farming). But many fires were thought to have been illegally set to clear land for large corporate agriculture, logging, and mining interests. Blame also fell on lax policing and the weakening of the environmental protection system in Brazil, where most of the fires occurred.

On Aug. 27, 2019, smoke rises above charred trees in the Amazon rain forest of northern Brazil. Credit: © Joao Laet, AFP/Getty Images

Forest fires are common in the Amazon during the dry season, from July to October. The fires are sometimes caused naturally by lightning strikes and exacerbated by drought, but most of the recent fires were probably started by people wanting to clear the land for other uses. There has been a vast increase in large, intense, and persistent fires along major roads in the Amazon, for example, something inconsistent with the randomness of lighting strikes. Climate change too is making the fires worse, as dry seasons in the Amazon become ever dryer, hotter, and longer.

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The Amazon rain forest covers much of northern South America. About two-thirds of the rain forest lies in Brazil. Credit: WORLD BOOK map

The fires (and the fire starters) have received divided attention in the Palácio do Planalto, the official workplace of the president of Brazil in Brasília, the capital. There, President Jair Bolsonaro has decreased environmental protections since taking office in January 2019, allowing an increase in deforestation—both legal and illegal, and always a problem—in the Amazon. Bolsonaro too has refused much international aid to help fight the fires, which continue to burn and destroy large portions of the rain forest. Bolsonaro eventually deployed some 44,000 soldiers to help the understaffed firefighters in the rain forest, and he agreed to coordinate firefighting efforts with other Amazonian countries. At the end of August, after the fires had raged for months, Bolsonaro also announced a 60-day ban on the legal setting of fires to clear land.

Deforestation results in the loss of vast areas of tropical rain forest each year. This photograph shows an area of the Amazon rain forest in Brazil that has been destroyed as part of slash-and-burn agriculture. In this method, farmers cut down trees and burn them. The ashes enrich the soil for only a brief period before the nutrients are depleted. The farmers then clear another area of forest. Credit: © Julio Etchart, Alamy Images

All seven Brazilian states that include parts of the Amazon have experienced sharp increases in fire activity in 2019. Numerous wildfires are also consuming alarming amounts of rain forest in the Amazonian regions of Bolivia, Paraguay, Peru, and Venezuela. The massive number of wildfires has greatly increased emissions of toxic carbon monoxide and the greenhouse gas carbon dioxide, a leading contributor to global warming. Smoke from the fires has obscured skies and aggravated such health problems as asthma, bronchitis, and chronic obstructive pulmonary disease (COPD) in people throughout the region.

August 3, 2018

For many people in the Northern Hemisphere, the summer of 2018 has been touched by fire and obscured by smoke. Summers are typically fire seasons in many areas, but climate change has caused hotter and drier conditions in recent years, and wildfire outbreaks have become more frequent and more destructive. Other causes of increased fire activity include the building of more developments in fire-prone areas, a lack of proper forest management, and, of course, simple human carelessness. In the past weeks, fires have killed more than 100 people and destroyed homes and large swaths of land in Asia, Europe, and North America.

A firefighting helicopter flies over a wildfire in the Greek town of Rafina near Athens on July 23, 2018. The Greek wildfire was the deadliest yet this year, claiming the lives of 92 people. Credit: © Angelos Tzortzinis, AFP/Getty Images

In southeastern Greece, a wildfire erupted July 23, destroying or damaging some 3,500 structures and killing 96 people along the Attica coast. The giant wildfire, just 18 miles (30 kilometers) east of Athens, the Greek capital, burned out of control for several days, gutting seaside resorts and holiday homes. Fanned by high winds, the fast-moving blaze trapped and killed groups of people, including entire families as they huddled between the flames and steep cliffs overlooking the Aegean Sea. The high death toll prompted criticism of the the area’s lack of access roads, warning systems, and other civil protection measures in areas surrounded by forest and at high risk of wildfires.

In far northern Europe, dozens of wildfires have consumed more than 62,000 acres (25,000 hectares) this summer in Sweden, which is experiencing an abnormally lengthy and intense heat wave. Neighboring Finland and Norway are also suffering from unusual heat and wildfire outbreaks, as are Estonia, Latvia, and Lithuania on the other side of the Baltic Sea. Wildfires also torched drought-stricken areas of Germany, the Netherlands, and Poland.

This week in northern California, firefighters continued to battle the Carr Fire that has killed 8 people, destroyed over 1,500 buildings, and consumed some 125,000 acres (50,000 hectares) of land. The wildfire started on July 23 along Carr Powerhouse Road in Shasta County near the city of Redding. The “mechanical failure of a vehicle” ignited dried grasses and trees, and soon flames were roaring through the forested hills around Whiskeytown Lake west of Redding. The wildfire, aided by hot and dry weather, high winds, an abundance of natural fuel, and steep terrain, has since been chased westward by more than 4,200 firefighters—2 of whom have died fighting the blaze. Reports of  “firenados” (huge, rotating whorls of smoke, flame, and ash) encouraged nearly 40,000 people to obey evacuation orders and leave the fire area (which included parts of nearby Trinity County). Many people will return to find their homes and property in ashes.

The Carr Fire is the largest of 17 wildfires currently burning throughout the state of California. Collectively, wildfires in the western United States have scorched 4.6 million acres (1.86 million hectares) so far this year, a 24 percent increase over the annual average for the past decade. Wildfires have also stricken large areas of western Canada and parts of Mexico this summer.

Wildfires have also consumed vast amounts of territory in Siberia of eastern Russia. Since May, firefighters have been battling immense wildfires in the Amur Oblast region along the Chinese border, where towering pyrocumulus clouds have injected smoke and pollutants high into Earth’s atmosphere. Pyrocumulus clouds are formed by rising heat from wildfires or by plume emissions from fossil fuel-burning industrial plants, and they sharply increase the levels of carbon dioxide and harmful aerosols in the atmosphere.

August 24, 2015

In an August 2015 photo, the sun turns red as it sets through the smoke behind the Olympic Mountains in central Washington. Wildfires in the state left a black, smoky haze hanging over the entire area.
(Credit: © Larry Steagall, Kitsap Sun/AP Photo)

Some 30,000 firefighters, including some who have arrived from Australia, Canada, and New Zealand, are being deployed this week to combat an unprecedented outbreak of wildfires blazing across the United States. In all, 17 states are actively fighting wildfires this August, during one of the driest and most explosive wildfire seasons on record. California, Idaho, Montana, Oregon, and Washington each report that at least 10 large wildfires are currently raging. These wildfires have claimed the lives of 13 firefighters.

A wildfire is the uncontrolled burning of large areas of vegetation. Depending on where they occur, such fires may also be called brushfires, bushfires, or forest fires. Wildfires may be ignited by human activities or by natural causes. Such natural causes include lightning or even intense sunlight. A wildfire can happen in any area with vegetation. Such areas include forests, grasslands, and shrublands. The intensity of a wildfire depends on the type of vegetation fueling it, the terrain, and the weather.

Since January 1, 2015, more than 41,000 individual wildfires in the United States have burned more than 7.2 million acres (2.9 million hectares), mostly in the Pacific Northwest and Alaska. That amount is already almost three times the 2.6 million acres that burned throughout the entire United States in all of 2014. This year’s fires have already burned more land than in any other year over the last decade. This year’s wildfires have been fueled by drought and record high temperatures.

Climate scientists attribute this year’s high temperatures and dry conditions to climate change caused by global warming. Data from the U.S. Forest Service indicates that the fire season, typically occurring over the summer months from June through August, now extends almost year round, averaging 78 days longer compared to fire seasons in the 1970’s. A huge mass of warm water that has settled in the Pacific Ocean off the West Coast of the United States is partially to blame. Climate scientists also point to a warm-water current called El Niño developing in the Pacific. In the United States, El Niño causes the climate to become drier than normal in the Pacific Northwest. Heavier-than-normal winter rains in the region, which often occur with El Niño, provide hope that this wildfire season won’t last.

Other World Book articles

• Bushfires in Australia
• Drought in California (a Special report)

September 16

Three of 11 wildfires—the Boles, Courtney, and King fires—burning in drought-stricken California have caused thousands of residents to evacuate their homes.  More than 150 structures have been destroyed by the wildfires in the last few days.

A map from the U.S. Drought Mitigation Center shows how extensive the drought is in California (dark red-brown represents extreme drought on the map). Drought has been a contributing factor in the nearly 5,000 wildfires that have burned in the state through mid-September in 2014. This figure represents 1,000 more fires than occur on average in a year, and September and October are the peak months for California wildfires. (Copyright 2014 National Drought Mitigation Center)

The severe drought afflicting California began in January 2012. Currently, 80 percent of the state is affected by extreme drought, characterized by widespread water shortages and restrictions and major loss of agricultural crops. The drought also means that grass and foliage in the state are extremely dry.

Unusually high temperatures—record-high, triple-digit temperatures— began in California on September 12. Yesterday, very high winds created the perfect conditions for raging wildfires. The winds spread the burning embers much faster than firefighters could extinguish them.

In the last 24 hours, the Boles wildfire in northern California destroyed 100 homes in the small town of Weed and caused at least 1,500 to evacuate. Some 300 acres (121 hectares) surrounding the town were burned. The interstate running through Weed was closed for a time and power to the town was knocked out.

Courtney and King fires in central California led to hundreds more evacuations on the same day. The King fire burned over 8,600 acres (3,480 hectares) by today. The Courtney fire has also burned over 300 acres.

Temperatures are predicted to drop in California by this weekend, but the ferocity and number of wildfires this week have strained fire departments across the state.

Additional articles:

• Weather (2013-a back in time article)
• Wildfires (A U.S. Geological Service website)

July 23, 2014

Wildfires fueled by higher-than-normal temperatures and lower-than-normal rainfall are burning an unusually large swathe of Canada’s Northwest Territories (NWT) this summer. At least 235 fires have consumed nearly 2.2 million acres (900,000 hectares), an area six times as great as the area normally affected each year during the past 25 years. Although the fires have swept across less than 1 percent of the vast NWT, the area burned equals more than the area of the states of Delaware and Rhode Island combined. More than half of the fires are burning out of control, according to the Canadian Interagency Forest Fire Center. The fires have forced hundreds of people from their home. Huge clouds of smoke and ash from the fires have also led Environment Canada, the government’s environmental protection agency, to issue poor-air-quality warnings for parts of the NWT as well as for the provinces of Alberta, Saskatchewan, and Manitoba. The smoke plume from the fires has spread thousands of miles (kilometers) south to North Dakota and South Dakota in the United States.

Daily temperature highs in Yellowknife, the capital and largest city in the NWT, have been running nearly 4 degrees Fahrenheit (2 degrees Celsius) above normal for July, while the city has received only about 2 percent of its average July rainfall. Meteorologists think that most of the fires have been sparked by lightning during “dry thunderstorms.” Such storms occur when the air below the clouds is so dry that any water falling from the clouds evaporates before it hits the ground.

Red dots mark the location of some of the large wildfires charing the Northwest Territories in Canada. Plumes of smoke from the fires have swept south and east through Canada’s prairie provinces into the United States. (Jeff Schmaltz MODIS Land Rapid Response Team, NASA GSFC)

The fires in the NTW are “in line with climate trends of more fires burning in the northern reaches of the globe,” according to Climate Central, an independant organization of climate scientists and journalists. A 2014 report by the Intergovernmental Panel on Climate Change, a United Nations committee, predicted that wildfire activity would double with every 1.8-Fahrenheit-degree (2-degree-Celsius) rise in average global temperatures. Such fires contribute to global warming by releasing soot, which darkens Arctic ice, promoting melting, and by adding more carbon dioxide to the atmosphere. Nearly all scientists think that the release of carbon dioxide and other greenhouse gasses into the atmosphere have significantly contributed to the rise in average atmospheric temperatures since the mid-1700′s. Forests in the NWT are part of the taiga, also called the boreal forest, a vast evergreen forest that circles the Northern Hemisphere. The taiga holds an estimate 30 percent of all the world’s carbon stored on land.

Additional World Book articles:

• Weather (2013) (a Back in Time article)
• Parched Earth (a Special Report)
• Weathering the Storm: Adapting to Global Warming (a Special Report)

February 6, 2014

The Republican-controlled U.S. House of Representatives passed legislation yesterday designed to address California’s current water shortage. The House bill would, among other things, roll back environmental protections and halt restoration of a dried-up stretch of the San Joaquin River in order to revive salmon runs. Republican members of the House blamed the water shortage on liberal environmentalist policies, arguing that fish were being put ahead of farmers. “We have listened to the environmental left for 40 years, and this is where it’s gotten us,’’ declared Representative Tom McClintock (R., California) on the floor of the House. Another California representative, Ken Calvert, said, “Congress can’t pass a bill to make it rain, but we can pass a bill to put an end to the water shortages that have been caused by misguided regulatory decisions.” Fully 33 percent of available water in California is used for the irrigation of crops. Democrats responded that the problem is simply a lack of rain.

Along with other parts of the West, California is undergoing a third straight year of severe drought. In late January, California Governor Jerry Brown declared a drought emergency, pointing out an extreme need for the conservation of water. He asked Californians to voluntarily reduce their water consumption by 20 percent. This is “perhaps the worst drought California has ever seen since records began being kept about 100 years ago,” stated Brown at a news conference. “We can’t make it rain, but we can be much better prepared for the terrible consequences that California’s drought now threatens, including dramatically less water for our farms and communities and increased fires in both urban and rural areas.”

Much of California's urban water comes from the spring melt of snow from the Sierra Nevada in eastern California. This winter's snowpack is dangerously low. (© Shutterstock)

The months of December through April are usually California’s rainy season, but not this year. Vegetation that typically rehydrates with rain during this period has continued to get dryer, becoming ever more dangerous. In January 2013, there were no wildfires in California; in January 2014, there were more than 400.

Much of the state’s urban water supply comes from the spring melt of the Sierra Nevada snowpack. While a good deal of the United States east of the Rockies has received above-normal amounts of snow this winter, California has received far less than normal. In late January, the California Department of Water Resources (DWR) reported that the Sierra snowpack was only 12 percent of the average amount for this time of the year, a record low. “If we don’t get more storms in here that actually dump some reasonable snowpack by April 1 . . .  [state reservoirs are likely to be] “alarmingly dry during the summer,” warned Dave Rizzardo, chief of DWR’s snow survey section.

Additional World Book articles:

• The Colorado River: Lifeline in the Southwest (a special report)

• How the Oceans Affect Climate (a special report)

• When the Rains Stop (a special report)

October 23, 2013

The Australian state of New South Wales is braced for another day of devastating bushfires. The commissioner of the New South Wales Rural Fire Service has urged people not to travel in various parts of the state due to conditions that are set to be “as bad as it gets.” Commissioner Shane Fitzsimmons warned that today’s weather forecast—temperature in the mid to high 80′s °F (30′s °C), humidity down to 10 percent, and winds of 50 to 60 miles (80 to 100 kilometers) per hour—is worse than previously thought, making it the most dangerous day yet in the bushfire emergency that began last week.

Dozens of bushfires are burning to the north, south, and west of Sydney, and the city is wreathed in smoke. “You can smell smoke inside buildings,” National Public Radio correspondent Stuart Cohen reported yesterday, noting that health authorities were expecting a surge in cases of people with respiratory problems. Since the start of the bushfires, more than 200 homes have been destroyed, and wildlife experts believe that thousands of koalas, opossums, reptiles, and other animals have been killed. However, only one life has been lost in the disaster.

A dangerous wildfire in the Blue Mountain region was started by the Australian army testing explosives in a military training exercise. (World Book map)

Firefighters from three states are battling the fires through backburning—that is, starting a fire that burns in the opposite direction to the line of the advancing wildfire. Australian fire officials say the threat to the Blue Mountain area west of Sydney “has been averted” for today, but warn the crisis is far from over. In total, 73 fires are burning across the state, 29 of them out of control. Meteorologists note that the severity of the bushfires is due to extremely dry conditions following Australia’s hottest September on record.

Additional World Book articles:

• Hakea
• Australia 2009 (a Back in Time article)

August 26, 2013

A rampaging wildfire in northern California that has already become one of the largest in that state’s history is expected to grow even bigger as difficult terrain, strong winds, and extremely dry conditions continue to thwart firefighters. As of this morning, the Rim Fire, which began on August 17, had scorched nearly 150,000 acres (60,700 hectares)–an area about the size of Chicago–and was only 15 percent contained. At least 3,000 firefighters were battling the fire on a number of fronts, aided by water and fire retardants dropped by helicopters and airborne tankers. The fire “has continued to pose every challenge that there can be on a fire,” a spokesperson with the California Department of Forestry and Fire Protection told the Washington Post. The fire is so large and ferocious that it is creating its own weather, the spokesperson said. “As the smoke column builds up it breaks down and collapses inside of itself, sending downdrafts and gusts that can go in any direction. There’s a lot of potential for this one to continue to grow.”

The Rim Fire is burning largely out of control in northern California, including parts of Yosemite National Park. (NASA)

The fire is also threatening power and water supplies to San Francisco, which is about 200 miles (320 kilometers) from the western edge of the blaze. Damage to electric power lines from two of the three hydroelectric power stations serving the city led California Governor Jerry Brown on August 23 to declare a state of emergency for the San Francisco Bay area. The city kept its electric power grid operational by purchasing power from other suppliers. On Sunday, the fire moved within several miles of the Hetch Hetchy Reservoir, which supplies about 85 percent of San Francisco’s fresh water. Officials were continually monitoring the reservoir’s water quality, which so far has been unaffected by falling ash.

The intense heat of the fire is threatening Yosemite's giant sequoias. (InciWeb/US Forest Service)

The fire has also overrun at least 15,000 acres (6,070 hectares) of the northwestern corner of Yosemite National Park. Campers and park staff have been evacuated from the affected area. Of particular concern to park officials are two of Yosemite’s famed stands of giant sequoias. Sequoias have a thick bark that protects them from fire, and they need fire to release their seeds and burn surrounding vegetation so new trees can spout. However, the Rim Fire is so hot that the trees’ canopies could be damaged. “All of the plants and trees in Yosemite are important, but the giant sequoias are incredibly important for what they are and as symbols of the National Park System,” a park spokesperson told the Associated Press.

Additional World Book articles:

• Forest fire
• Muir, John
• Sequoia National Park
• Sequoyah
• Why Forests Need to Burn (a special report)