In a Parched US, Human-Triggered Wildfires Are Poised to Thrive

After a soaking peak hurricane season, much of the United States is now parched. At the end of October, the U.S. Drought Monitor found that around 87 percent of the contiguous U.S. was in the throes of abnormally dry to exceptional drought conditions—a record high in the federal program’s 25-year history. 

These continuing droughts go hand in hand with another environmental risk: wildfires. In recent weeks, a spate of these fires have broken out from California to New York, largely fueled by dried-out vegetation. Research shows that nearly 85 percent of wildland fires in the country are caused by human activities. 

To make matters worse, recent data reveals that human-triggered fires are often more destructive and harder to contain than those that are sparked naturally. Experts say communities must make some major changes to avoid succumbing to the flames. 

Heating Up and Drying Out: This October wasn’t just the driest on record for many states, it was also one of the warmest. The month’s average temperature of 59 degrees Fahrenheit in the contiguous U.S. was almost 5 degrees higher than the 20th-century average, according to the National Oceanic and Atmospheric Administration (NOAA). 

These balmy fall temperatures sucked moisture out of soil through evaporation and dried out vegetation. Meanwhile, high pressure in the upper atmosphere—a phenomenon known as “ridging”—kept widespread rain at bay in the central and eastern U.S., NOAA reported. The drought spread incredibly fast, from covering 12 percent of the country in June to 54 percent as of Oct. 29, with many other places in near-drought conditions. Research shows these “flash droughts” are increasingly common around the world as climate change hikes up temperatures and messes with rainfall patterns.

These conditions cultivate an ideal environment for a fire to thrive. Add in some fuel (such as the dry vegetation I mentioned earlier) and all it takes is one spark to trigger an inferno. 

Lightning can spark fires naturally in ecosystems, but humans are responsible for a growing number of ignitions each year. A fallen power line caused the 2023 fires that tore through Maui and decimated the town of Lahaina. Each year, fireworks ignite thousands of wildfires, which I wrote about this summer. Last week, sparks from a shotgun lit up brush in Jackson Township, New Jersey, which torched 350 acres of land and prompted evacuations in the drought-ridden region. Several other fires are raging through the East Coast simultaneously, though their causes are not yet confirmed. 

So why do human-caused wildfires wreak more havoc than their naturally sparked counterparts? Lightning strikes often occur during storms, when rain and high humidity can tamp down a fire before it spreads, Virginia Iglesias, who studies the effects of climate variability on social-environmental systems at University of Colorado Boulder, told me. Human activities, on the other hand, typically spark fires under extreme conditions like the ones the U.S. is currently experiencing. That can fuel higher flames and faster spread. 

Ongoing work by Iglesias suggests that human-caused fires from 2001 to 2018 destroyed significantly more structures than lightning-triggered fires. With more opportunities for ignitions, humans have tripled the length of fire seasons across the United States since the early 1990s. 

“There’s cigarette butts, there’s power lines, there’s arson. It happens throughout the year,” Iglesias said. “Those fires wouldn’t have happened without ignition, and humans are providing the ignition. So we end up with these huge, super-fast fires.” 

Changing Fire Landscapes: In recent decades, urbanization has rapidly encroached on natural ecosystems. This overlapping space of human development and wilderness is known as wildland-urban interface, and has expanded worldwide by roughly 35 percent since 2000. 

Living in these areas may offer more solitude and nature than a large city, but it also brings an increased threat of fire, according to a study published in March. The researchers found that while global total fire counts decreased by 10 percent from 2005 to 2020, the fraction of fires that occur in the wildland-urban interface increased by 23 percent.

Along with the increased fire frequency, what’s burned in this zone can pose risks to people as well. When fires scorch cars, homes and other human-made materials, they may release toxins and carcinogens that harm health and ecosystems, according to a 2022 report commissioned by the federal government. For example, ash left behind by the Lahaina fires contained elevated levels of arsenic, lead and cobalt. In the fire’s aftermath, the Hawaii State Department of Health urged residents to mop and wipe down counters every day to avoid inhaling the chemicals. 

Some scorched materials can also accelerate the fire’s spread, Iglesias said. 

“Homes have several materials that are drier than vegetation,” she said. “For instance, a porch is drier than a tree, and so that makes it more fire prone.” 

Another shift to the country’s fire regime: Climate change and land use changes may be making wildfire risk more prevalent in the Northeast. Parts of New Jersey and coastal New York are experiencing at least 10 additional days of fire weather each year compared to the 1970s, according to an analysis by the nonprofit Climate Central. Such days have a combination of high heat, low humidity and strong winds.

There’s a similar risk out West, but communities in this area are often more prepared to face fires than those along the East Coast, Iglesias said.

“People who do not think [they] are in fire-prone areas are going to start seeing fire, and it’s quite likely that those people are not going to be ready because they haven’t been exposed in the past,” she said. 

Experts say that regulated, controlled fires known as prescribed burns, set in low-risk conditions, can help reduce the amount of brush that may spark up during droughts. In the meantime, many areas along the East Coast are still under Red Flag warnings, with residents told to avoid setting any kind of fire until the advisory is lifted. 

More Top Climate News 

President-elect Donald Trump tapped former U.S. Rep. Lee Zeldin (R-N.Y.) to lead the Environmental Protection Agency during his term, which starts in January. The announcement came as a surprise to many, but conservatives were quick to praise Trump’s choice of Zeldin, who told Fox News on Monday that he will prioritize industry over public health protection and focus on deregulation, Jean Chemnick and Scott Waldman report for E&E News. Zeldin was a member of the House’s Bipartisan Climate Solutions Caucus and once opposed Trump’s offshore drilling plan, but supported expansion of fossil fuels during his unsuccessful run for New York governor in 2022. 

World leaders have gathered in Baku, Azerbaijan, for the 29th climate summit (COP29), where my colleague Bob Berwyn is reporting on the ground. In his first article, Berwyn discussed how Trump’s impending presidency is looming over the conference, where environmentalists are pushing countries to pledge deeper cuts for emissions and commit more funding to low-income countries bearing the brunt of climate impacts. The president-elect has pledged to pull the U.S. from the Paris Agreement, which could influence other countries, experts say. 

“If you know that there is no way that the U.S. is going to participate in any shape or form, and that whoever is there in terms of negotiators won’t really have a mandate to negotiate anything, it’s really hard to see how you could entice countries that already feel that they’re going to be stiffed [to negotiate],” Liane Schalatek, associate director of the Heinrich Böll Foundation in Washington, D.C., told Inside Climate News. 

Meanwhile, a Dutch appeals court overturned a 2021 ruling that ordered oil and gas company Shell to cut carbon emissions 45 percent by the end of the decade, Stanley Reed reports for The New York Times. The previous decision was the first time a court ordered a private company to align its efforts with the goals of the Paris Agreement, but Shell argued that the company does not have control over how customers use its products and only governments could enforce this type of mandate. Experts say the case could disrupt climate activists’ attempts to use the legal system as a strategy to hold corporations accountable for their climate contributions. 

Farmers in New York are struggling to grow crops under drought conditions, an increasingly common problem with climate change, Frida Garza reports for Grist. Without rain, many of the farmers’ seeds will not sprout or germinate in the coming months, which could affect their overall income for the year. In the energy world, the U.S. Energy Information Administration forecasts that “hydropower plants in 2024 will be 13% less than the 10-year average,” largely due to drought. 

New York Gov. Kathy Hochul is considering ways to revive congestion pricing in New York City, though at a lower cost than originally pitched, Anthony Izaguirre reports for The Associated Press. Hochul’s team has been connecting with state lawmakers to gauge potential support of the plan, which was put on an indefinite pause this summer, triggering backlash from environmentalists.