How wildfires have worsened in recent decades

FILE -- Diamond Fire burns near Scottsdale, Arizona, in June 2023.
FILE -- Diamond Fire burns near Scottsdale, Arizona, in June 2023.(azfamily)
Published: Jul. 5, 2023 at 12:54 PM MST
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(Stacker) - Earlier this month, residents throughout the Northeast woke to hazy orange skies as smoke blew down from a nearly 12-million-acre wildfire burning in Quebec, threatening national forests and property throughout the province. Thirteen American states issued air quality alerts, highlighting the impact of large-scale fires beyond their immediate path.

Wildfires are innate to forest ecosystems, clearing out dead debris and paving the way for new growth, but climate change has elongated dry seasons, increased temperatures, and widened the potential for large-scale wildfires. Beyond weather-related factors, the prevalence of insects like bark beetles damage trees and make them more prone to burning. Invasive vegetation such as cheatgrass also easily burns and contributes to spread.

Trees, traditionally a storage vessel for carbon, release carbon immediately when burning and during decomposition. The EU’s Copernicus Atmosphere Monitoring Service estimated that global wildfires in 2022 released 1,455 megatonnes of carbon emissions. Black carbon, or soot, can also travel beyond wildfire zones, absorbing sunlight and warming the earth further.

Beyond the environmental threats, the widening reach of wildfires threatens the displacement of countless residents. Despite this, people continue moving to wildfire-prone areas, putting a growing population at risk of longer fire seasons and associated health risks.

Stacker cited data from the National Interagency Fire Center and the National Oceanic and Atmospheric Administration to visualize how the spread of wildfires has worsened in recent years.

The number of wildfires is decreasing, but more acres are burning

Throughout the mid-20th century, forest management largely focused on preventing forest fires of all scales. Smokey the Bear was a national mascot for fire prevention, overseeing a multi-decade decrease in the number and average size of fires. But without regular fires, debris built up. This, combined with other environmental factors, eventually fueled costlier, large-scale blazes that have come to define the current wildfire season.

Line chart showing fewer wildfires are burning more acres. The 10-year average of acres burned...
The 10-year average of acres burned has increased 166% since 1992 while the number of wildfires has fallen 4%.(Stacker)

Despite having nearly 10,000 fewer fires per year on average from 2011-2021 compared to 1983-2010, the average acreage burned by those fires per year has more than doubled. From 1983-2010, the average number of acres burned per year was about 4.4 million. That number has jumped to 7.5 million acres per year for the 2011-2021 time period.

Wildfire seasons are getting longer

The total acres burned by wildfires in December 2020 was three times greater than the 10-year average for the month. The following year also experienced a damaging December, with a less extensive but still above-average spread covering 336,984 acres. Wildfire season traditionally lasts May through October, but shorter winters and earlier snow melts have extended wildfire risk. 2021 set a record for days at preparedness level 5, the highest alert for wildfire risk.

Ridgeline plot showing wildfire season is getting longer and more damaging. The average number...
The average number of acres burned per fire has increased and large scale fires are extending further into the year.(Stacker)

The USDA Forest Service warned in 2021, “For years, agencies relied on seasonal firefighters for summer months, but now that wildfires are burning into the winter, they need to reevaluate their hiring plans.”

Wildfire suppression costs have risen by billions of dollars

With the increasing severity of wildfires every year, it follows that more resources are required to tame the blazes. In 1999, just before the turn of the century, the Forest Service and all other Department of the Interior agencies spent a combined $515.5 million on wildfire suppression. During the course of the last decade, the average cost of wildfire suppression has skyrocketed to nearly $2.1 billion annually. The Forest Service carries the brunt of this cost, contributing approximately three-quarters of the funds each year.

Stacked column chart showing wildfire suppression costs are increasing. 2021 was the most...
2021 was the most costly year for wildfires, reaching over $4.3 billion, over 40-times higher than 1985 when adjusted for inflation.(Emma Rubin | Stacker)

Though there is not currently an official tracking mechanism for the cost of wildfire damages, academics across the country have attempted to estimate the economic impact of wildfires. In 2020, a team of researchers estimated that the 2018 California wildfires caused $148.5 billion in economic damages.

Lightning fires are causing more damage in the West

At the national level, 89% of wildfires were caused by humans in 2022, but human-caused wildfires contributed only to 44% of the total acreage burned. In the Southern and Eastern U.S., human-caused fires still cause the most damage, but elongated dry seasons in the West have intensified the impact of lightning when it does strike.

Map showing that in the Northwest and California, lightning is becoming a more prominent cause...
This map shows that in the Northwest and California, lightning is becoming a more prominent cause of wildfires.(Stacker)

Dry lightning is created through high-altitude thunderstorms. Extreme heat and drought can cause rain to evaporate before it reaches the ground. Lightning fires can also pose greater damage because it can take longer for them to be detected, whereas human-caused fires are often closer to towns and high-traffic areas. Winds associated with dry thunderstorms can further fan the flames as well. These factors mean that even as the West is less prone to lightning than other parts of the country, the bolts can spark more damage.

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