As a forest ecologist who has been studying the links between wildfires and climate change since the early 1990s, Susan Prichard is well aware that global warming is contributing to longer and more intense fire seasons around the world.
Yet, nothing could have prepared her for the past 12 months.
As 2020 began, record-breaking wildfires had already engulfed regions of Australia, eventually scorching more than 65,000 square miles — an area that, when taken together, is larger than the state of Illinois. Then came the fires that swept across Siberia in July, fueled by an intense Arctic heat wave. And then things hit much closer to home for Prichard.
Over the past month, dozens of catastrophic wildfires have been raging along a huge swath of the western United States, including in Prichard’s home state of Washington. Millions of acres have already burned across California, Oregon and Washington, and at least 36 deaths have been linked to the blazes.
“What strikes me is that the future we were really worried about and that us climate scientists talked about for decades, we’re living through that now,” Prichard, a research scientist at the University of Washington, said.
Experts predict that in a warming world, devastating wildfires like the ones burning now will be even more common. Studies have shown that in addition to becoming more frequent, climate change will likely make such blazes more destructive, which carries enormous environmental, financial and health consequences for communities most at risk.
And in some countries, including the United States, supercharged wildfire seasons could be exacerbated by climate-related disasters elsewhere in the country, such as hurricanes or other extreme weather events, that culminate in multiple colliding crises that threaten the stability of various communities.
“Individual things like a bad hurricane season, bad flooding or bad wildfires are not that surprising because literally every climate scientist predicted these things would happen,” said Sarah Perkins-Kirkpatrick, a senior research associate at the Climate Change Research Centre at the University of New South Wales in Australia. “But seeing all these things happen in one year — in some cases, simultaneously — is shocking and does make me worried about what the next 10 years are going to look like.”
Though they occurred thousands of miles apart, on different continents and different terrains, there are some similarities between the wildfires in Australia and those in the western U.S., according to Mike Flannigan, director of the Western Partnership for Wildland Fire Science at the University of Alberta in Canada.
In both places, the fire seasons started earlier than normal amid persistent drought conditions, he said. Lightning also played a key role in igniting fires in Australia and in California, in particular.
But no matter where they occur, wildfires need two main ingredients to sustain themselves: conducive fire weather — dry conditions together with lightning and wind, for instance — and “fuel,” which in this case refers to dead trees, dried-out leaves and any other material that can burn up.
Seasonal wildfires occur naturally around the world, but as temperatures rise due to global warming, the atmosphere can more efficiently pull moisture out of leaves, pine needles and the forest floor, Flannigan said. Without precipitation to compensate, this can create ideal conditions for a wildfire.
“It makes it easier for fires to start, whether from a lightning bolt or somebody’s campfire,” Flannigan said. “It also becomes easier for fires to spread because there’s more fuel to burn, which means we can get these higher intensity fires that are difficult or nearly impossible to put out.”
It’s been known for some time that climate change is increasing wildfire activity and lengthening wildfire seasons. A 2006 study led by Anthony Westerling, a climate scientist at the University of California, Merced, found that wildfires in the western U.S. increased significantly beginning in the 1980s. The researchers also found that the average length of fire seasons between 1987 and 2003 had increased by 78 days, compared to the period from 1970 to 1986.
“Ultimately, a longer fire season means there’s more opportunity to have extreme fire days and extreme fire weather,” Kate Wilkin, a fire ecologist at San José State University, said.
In a follow-up study published in 2016, Westerling showed that longer, busier fire seasons were largely the result of warming temperatures and earlier spring snowmelt.
These twin factors were to blame for the Siberian fires that raged over the summer. Unusually warm temperatures in the Arctic — including a heat wave that saw the Russian town of Verkhoyansk hit a record-high 100.4 degrees Fahrenheit on June 20 — thawed the Siberian tundra and fueled the region’s intense blazes.
Similar dynamics, albeit across vastly different landscapes, are playing out around the world. And while climate change is not the only factor at play, it is the driving force, according to Daniel Swain, a climate scientist at the University of California, Los Angeles. Global warming essentially stacks the deck by not only increasing the chances that wildfires occur, but also increasing their severity when they do.
“Wildfires aren’t new in any of these places, but the character of the fires — how quickly they become very large and destructive — is shocking, even compared to recent extremes,” he said.
In places like California, climate change is making it so that wildfires are less defined by a season and have instead become a year-round threat. The implications of such a shift go beyond concerns about forest ecosystems and their ability to bounce back. Over the past month, the West Coast has been shrouded in thick smoke, with cities such as Portland in Oregon, Seattle and San Francisco ranking among the top 10 places in the world with the worst air quality.
Wildfire smoke is dangerous to inhale because it contains very fine particles that can penetrate deep into the lungs.
“The body responds by releasing the same immune cells it would to fight a virus, but unlike a virus, these particles can’t be broken down,” Perry Hystad, an environmental epidemiologist at Oregon State University, said. “They can reach the bloodstream, the heart, liver and even the brain, so these small particles can create all kinds of short- and long-term health concerns.”
Prolonged exposure to wildfire smoke is especially worrisome, he added. Some communities in California, for example, have been under air quality advisories for more than 40 consecutive days. These concerns also become magnified with longer and more severe wildfire seasons.
“A lot of people treat these as one-off disasters, but we’re definitely seeing higher annual exposure concentrations than we typically experience,” Hystad said. “We need to start treating wildfire smoke exposure as semichronic as fires become more routine.”
Raising awareness about the health impacts of wildfires will need to be part of how society adjusts to “a new reality” with wildfires, according to Prichard.
“We’ve now stepped into our climate change future, so what do we do about it?” she said. “How do we work with natural ecosystems and become more fire-adapted?”
Part of those discussions will likely involve reevaluating land management strategies, which could include expanding what’s known as prescribed burning, Prichard said. This practice of intentionally setting fires to clear downed trees and other vegetation that would be susceptible to blazes is one way that forest managers try to reduce hazards ahead of peak fire seasons.
Outreach campaigns, such as Firewise USA, could also help individual homeowners and communities reduce their wildfire risks and better protect themselves.
Any adaptations will need to be swift, in order to avoid years with devastating wildfires as 2020 has been so far, according to Swain.
“Not every year will be as extreme as it’s been in Australia or on the West Coast, but we’re seeing that the ceiling for what’s possible is rising,” Swain said. “And that’s not a good thing, because the ceiling was already high in terms of how bad these wildfires could be.”