Burning Alaskan permafrost increasing methane emissions

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The flames have died out on Alaska’s largest river delta, but emissions are still seeping out of the tundra’s ground.

A recent NASA study found that methane “hot spots” in the Yukon-Kuskokwim Delta are more likely to be found where wildfires burned into the tundra. The greenhouse gas reportedly originates from decomposing carbon stored in the tundra’s permafrost for thousands of years.

“We find that [methane] hotspots are roughly 29 percent more likely on average in tundra that burned within the last 50 years compared with  unburned areas, and that this effect is nearly tripled along burn scar perimeters that are delineated by surface water features,” the researchers said. “Our results indicate that the changes following tundra fire favor the complex environmental conditions needed to generate emission hotspots.”

Mackenzie Delta, Northwest Territories
Mackenzie Delta, Northwest Territories

The correlation also nearly tripled in areas where fires burned to the edge of a lake, stream, or other body of standing water, according to NASA. The highest ratio of methane hot spots occurred in recently burned wetlands. Researchers detected roughly 2 million hot spots across 11,583 square miles. The team believes more hot spots could soon emerge.

“By some projections, the fire risk in the Yukon-Kuskokwim Delta could quadruple by the end of the century due to warming conditions and increased lightning storms – the leading cause of tundra fires,” they said.

Alaska had two of its largest tundra fires ever in 2022. The East Fork Fire ignited on May 31 after a lightning strike, and burned more than 150,000 acres along the Yukon River. The Apoon Pass Fire, the second largest, burned 84,130 acres.

Previous research found that the majority of yearly methane emissions from Alaska’s tundra occur during the cold season between September and May, indicating that total emissions are sensitive to soil climate and snow depth.

Grassfires destroy far more homes than forest fires

A devastating series of wildfires that swept over forests in Idaho, Montana, and Washington more than a century ago — the Big Burn of 1910 — would forever change the nation’s perception of fire in forests. The lessons learned from that tragedy, however, may have been a bit misguided, according to new research.

Firefighters had been putting out fires for months in 1910 throughout the Western states. They’d finally begun to get ahead during the week of August 19, even beginning to dismiss some firefighters, according to the Forest History Society.

But then all hell broke loose. Hurricane-force winds roared across the states, turning numerous smoldering embers into firestorms.

“A forester wrote of flames shooting hundreds of feet in the air, fanned by a tornadic wind so violent that the flames flattened out ahead, swooping to earth in great darting curves, truly a veritable red demon from hell,” according to a summary document by the USFS.

1910 fires

What became known as the “Big Blowup of 1910” is largely remembered for killing 86 people (78 of whom were firefighters), burning 3 million acres, and completely destroying eight towns.

Wallace, Idaho -- the aftermath
Wallace, Idaho — the aftermath

The fire burned its way into the American conscious, one of the first widely reported wildfire tragedies in the nation’s budding national news system.

Three future Forest Service chiefs were directly involved in the Big Blowup, including W.B.Greeley, Henry Graves, and Ferdinand Silcox, and their experience would go on to shape decades of policy around aggressive fire suppression in U.S. forests. Not only has research shown aggressive suppression to be an ill-advised effort, but the heightened focus on fires in the nation’s forests may have also been misguided.

New research found rising wildfire risk for houses across the United States, with the number of homes within wildfire perimeters doubling since the 1990s, caused by both housing growth and more burned areas. Researchers also got a surprising finding from their study: grassland and shrubland fires destroyed far more houses than those lost to forest fires.

“This pattern was most pronounced in the Western U.S., which encompassed 69 percent of all the buildings destroyed by wildfires,” the researchers wrote. “There, 79.5 percent of all destroyed buildings were lost in grassland and shrubland fires. In the East, by contrast, 82.1 percent of destroyed buildings were lost in forest fires. In the West, even though forests had a high destruction rate (21.3 percent), only 2,367 buildings were destroyed by forest fires compared with 9,402 in grassland and shrubland fires.”

The researchers noted multiple potential reasons for the heightened number of homes destroyed by grassland and shrubland wildfires compared with forest wildfires, including the sheer acreage of grasslands and shrublands throughout the country. From 1990 to 2020, grassland and shrubland accounted for 64 percent of the total area burned by wildfires at ~91 million acres, while forests made up only 27 percent of burned areas at ~34 million acres.

Another reason is the difference in vegetation in the two environments. Wildfire management across grassland and shrublands requires frequent application of multiple types of risk-management strategies, including prescribed burning and fuel thinning, compared with forests — because of the quick recovery of fuel loads in grassland areas. The risk-management strategies, however, may not be advisable in all grasslands and shrublands, specifically those where fire-prone invasive species have replaced native vegetation.

In the West, 79.5 percent of all destroyed buildings were lost in grassland and shrubland fires.

Despite more homes being destroyed by grassland and shrubland wildfires, homes near forest wildfires reportedly have an above-average chance of being destroyed.

“Of the 151,725 buildings … that were exposed to wildfires from 2000 to 2013, 11.3 percent were destroyed,” researchers said. “However, buildings in evergreen and in mixed forests were almost twice as likely to be destroyed (20.1 and 22.9 percent, respectively). By contrast, the destruction rate for shrublands was similar to the average (12.7 percent), and rates for grasslands and deciduous forests were considerably lower (8.0 and 3.3 percent, respectively).”

Researchers believe this is the case partly because of forest wildfires’ higher intensity, but also couldn’t rule out the difference in the architecture of homes built in forests compared with homes built in grasslands and shrublands.

The study concluded by noting that stricter construction standards and land-use planning, specifically avoiding building in areas prone to fire, would help the Forest Service meet its goal of limiting wildfire risk for  newly developed housing.

Wildfire smoke toxicity worsened by heavy metals in soil, flame intensity

The job of wildland firefighters is grueling; long treks into the wild and countless hours of manual labor on the job take their toll. Because of this, gear is often reserved for the bare essentials like flame-resistant clothes, hard hats, and tools to cut a fireline.

Urban firefighters, on the other hand, are outfitted like armored tanks with gear that’s nearly triple the weight of what the wildland firefighter carries. The most obvious visual difference in their gear is a breathing apparatus, meant to protect structural firefighters from smoke. Despite this, cancer remains the largest killer of urban firefighters, in part because of the synthetic materials that burn inside buildings and release toxic chemicals into the air.

A self-contained breathing apparatus (SCBA) is a device worn to provide an autonomous supply of breathable gas in an atmosphere unsafe for breathing — which structural firefighters often encounter.

Development of a wildland fire respirator. Two versions are being tested, with the filter being carried on the chest hip. Department of Homeland Security photo.
Development of a wildland fire respirator. Two versions are being tested, with the filter being carried on the chest hip. Department of Homeland Security photo.

A breathing apparatus or mask hasn’t historically been a staple of wildland firefighters’ gear, though some have been in testing for years. The added heavy carry capacity is one reason, along with the assumed lack of toxic chemical inhalation, since the fire’s burning in a natural area free from synthetic materials.

That assumption isn’t true, according to new research from Stanford University. Wildfire can actually create cancer-causing toxic heavy metals depending on where they burn and the severity of the flames.

“Soil-and plant-borne chromium is of particular concern,” the research team told WildfireToday. “Altered by fire, chromium is transformed into its toxic hexavalent state. We show that fire severity, geologic substrate, and ecosystem type influence landscape-scale production of hexavalent chromium in particulates during recent wildfires.”

The Stanford team researched soil and ash gathered from the 2019 Kincade Fire and the 2020 Hennessey Fire within the LNU Lightning Complex for their study. At the burn scars, the team measured the levels of chromium 6, which is known by most as the toxic chemical from the 2000 film Erin Brockovich, and they found dangerous levels of it in certain areas of the fire.

The chemical was present in heightened amounts where the soil had a greater concentration of metals from the area’s geology and had also been severely burned. Areas that weren’t on metal-rich geologies, or that had burned at a low severity, had either non-detectable chromium 6 levels or very low levels not of concern.

“Up until now, for wildfires at least, we’ve worried a lot about the fine particulate exposure … what we’ve been blind to is that those ultra-fine particles can differ in composition,” researcher Scott Fendorf said. “Even in wildfires that are completely removed from any dwellings, with certain geologies and certain vegetation types which are pretty common, we can see that the particles have these toxic metals in them.”

The team’s findings may not only help define the health risks wildland firefighters face in certain wildfires, but may also help in understanding what risks nearby populations may experience when inhaling air downwind of wildfires. In areas that experienced dry post-fire weather, chromium 6 was found to last on the soil’s surface in wind-dispersible particulates for up to a year after the fire was extinguished.

Researcher Alandra Marie Lopez hopes to further her research for this study and use the findings to examine what levels of chromium 6, if any, are found on landscapes post-prescribed burning. Additionally, the team hopes to use the research to create a risk analysis map to determine which areas and geologies after severe burns pose the greatest risk to human health.

Redwoods are sprouting 1000-year-old buds

When lightning ignited fires in California’s Big Basin Redwoods State Park north of Santa Cruz in August 2020, the fire spread quickly. Redwoods naturally resist burning, but these fires reached the canopies of trees over 300 feet tall. “It was shocking,” says Drew Peltier, a tree ecophysiologist at Northern Arizona University. “It really seemed like most of the trees were going to die.”

Yet many of them lived, according to a report in Science magazine, and in a paper published in Nature Plants, Peltier and his colleagues explain why:  The burned trees, despite losing their needles, mobilized their long-held energy reserves, the sugars that were produced from sunlight decades ago. The trees routed this energy into dormant buds under the bark.

“This is one of those papers that challenge our previous knowledge on tree growth,” says Adrian Rocha, an ecosystem ecologist at the University of Notre Dame. “It is amazing to learn that carbon taken up decades ago can be used to sustain its growth into the future.”

When the wildfires in 2020 burned through Big Basin Redwoods State Park, reported the San Francisco Chronicle, they left some of the oldest trees on the planet badly burned; researchers now have estimates of  just how old the energy reserves of those redwoods are. Researchers studying a stand of severely burned old-growth redwoods found the buds were more than 1,000 years old.

Mild fires burn through coastal redwood forests about every decade, and the giant trees resist flames in part because the bark is up to a foot thick on the lower trunks, and it contains tannic acids that are fire-resistant. But in 2020 even the uppermost branches of many trees burned and their ability to photosynthesize went up in smoke along with their needles. Giant sequoias — which are different from the redwoods — can live for up to 3000 years, but in 2020 about 10 to 14 percent of the giant sequoias in the Sierra Nevada that were at least four feet in diameter were killed in the Castle Fire on the Sequoia National Forest.

A single sprout pushing up through thick redwood bark in Big Basin Redwoods State Park, as seen in April 2021.

Courtesy of Drew Peltier/Northern Arizona University 2021

A sprout emerges from thick redwood bark in Big Basin Redwoods State Park — 2021 photo by Drew Peltier, Northern Arizona University

Fire managers weren’t sure the trees on the Sequoia and in Big Basin would make it, but visiting the state park a few months after the fires, Peltier and his colleagues found fresh growth emerging from the trunks of blackened redwoods. They knew that shorter-lived trees can store sugars for several years. Because redwoods can live for more than 2000 years, the researchers wondered whether the trees were drawing on much older energy reserves to grow these new sprouts.

Within about 5 months, ancient trees had mobilized old stores of carbohydrate to resprout.LISSY ENRIGHT/U.S. FOREST SERVICE
Within about 5 months, ancient trees had mobilized their old stores of carbohydrate to resprout. LISSY ENRIGHT/USFS photo

Melissa Enright with the USFS covered parts of 60 blackened tree trunks with black plastic to block out sunlight, ensuring that any new sprouts would grow with only stored energy, not new sugars produced from current photosynthesis. After 6 months, the team brought some sprouts back to the lab, and they radiocarbon-dated them to calculate the age of those sugars. At 21 years, they are the oldest energy reserves shown to be used by trees.  But the mix of carbohydrates contained some carbon that was much older, and Peltier calculated that the redwoods’ carbohydrates were photosynthesized nearly 6 decades ago.

“They allow these trees to be really fire-resilient because they have this big pool of old reserves to draw on,” Peltier says. These redwoods have formed new sprouts, but Peltier and other forest researchers wonder how the trees will cope with far less energy from photosynthesis, considering that it will be many years before the trees can grow as many needles as they had before.

“It is likely that other long-lived trees also harbor carbon reserves that are much older than previously recognized,” said Peltier. The carbon stores observed in the trees, he told a Forbes reporter, date back as far as 1500 years, and they may provide hope for other ancient trees “destroyed” by fire.

Wildfire exposure felt unequally among elderly, low-income populations

Around 90 percent of all people exposed to wildfires over the past 23 years lived in either California, Oregon, or Washington. Among those, researchers found a disproportionate number were poor, a racial minority, disabled, or over the age of 65.

A recent study examined the “social vulnerability” of the people exposed to wildfires over the last two decades. Social vulnerability describes how persons with certain social, economic, or demographic traits were more susceptible to harm from hazards including wildfires or other natural disasters.

From 2000 to 2021, the number of people in the western United States who lived in fire-affected areas increased by 185 percent, while structure losses from wildfires increased by 246 percent. The vulnerability of the people living there, however, isn’t well known despite these populations potentially never recovering after a disaster strikes.

Researchers asked whether highly vulnerable people were disproportionately exposed to wildfire, how vulnerability has changed over the past 20 years, whether population changes before a fire alter the vulnerability of the population, and whether social vulnerability of people exposed to fires was equal among states.

Each of the three West Coast states recorded disproportionate wildfire exposure of the socially vulnerable; Oregon and Washington had more than 40 percent of their exposed population being highly vulnerable while California had around 8 percent of of those exposed considered highly vulnerable. The most vulnerable populations were also those with low income, while age, minority status, and disability also affected populations’ ability to cope after wildfire.

The number of highly vulnerable people exposed to fire in the three states also increased by 249 percent over the past two decades. An increase in social vulnerability of populations in burned areas was the main contributor to increased exposure in California, while Oregon and Washington saw wildfires increasingly encroaching on vulnerable population areas.

“Our analysis highlights the need to increase understanding of the social characteristics that affect vulnerability, to inform effective mitigation and adaptation strategies,” the study said. “Particular attention to residents who are older, living with a disability, living in group quarters, and with limited English-speaking skills may be warranted, and cultural differences need to be addressed for effective policy development and response.”

Other research published earlier this year, The Path of Flames: Understanding and Responding to Fatal Wildfires, found unequal access and assistance could also play a role in who survives and who dies during catastrophic wildfires. In the study, researchers found that for many of the Paradise, California  residents who died in the 2018 Camp Fire, the inability to evacuate on their own was a major factor in their deaths.


More simultaneous large fires in the next 60 years

Wildfire simultaneity, or numerous large wildfires burning at the same time, will become at least twice as frequent by 2085, researchers are warning. A steadily increasing number of large wildland fires — and the number of acres burned — has occurred over the past few decades in the American West, but new research has found that simultaneous large fires will burn even more often. 

Future regional increases in simultaneous large Western USA wildfires” was published in the International Journal of Wildland Fire by the University Corporation for Atmospheric Research; it focused on wildfires that burned 1,000 acres or more between 1984 and 2015. Researchers  used multiple fire indices to model how simultaneity will likely change over the next 60 years. The study also measured the fires by Geographic Area Coordination Centers to see whether some geographic areas might see greater increases compared with others.

changes in simultaneity

Simultaneous wildfires were projected to increase in every area of the West. Not only were “bad years” projected to increase, but increases in simultaneity also led to more intense wildfires. Peak season for simultaneous wildfires was projected to become several weeks longer by the end of the century.

“The trend was particularly pronounced for the most severe wildfire seasons — those that currently occur only every 10 years on average,” the National Center for Atmospheric Research said. “In the future, such seasons may be expected to occur at least twice as often, and up to nearly five times per decade in the northern Rocky Mountains, which was the most affected region.”

seasonality of simultaneity
Projected seasonality of simultaneity

The findings point toward a risk in an already understaffed and under-resourced wildland firefighting force. Because crews are transferred across the nation, or sometimes even across nations, to battle fires depending on when an area’s season peaks, an increase in peak season length could mean major challenges for firefighters and fire managers.

“Because firefighting decisions about resource distribution, pre-positioning, and suppression strategies consider simultaneity as a factor, these results underscore the importance of potential changes in simultaneity for fire management decision-making,” the study says.

Steps can reportedly be taken to lessen the future risk of simultaneous wildfires, including thinning forests, conducting prescribed burns, and increasing numbers of firefighting crews and equipment. But that will depend on how long it will take to make those changes.

“The strain on resources created by simultaneous fires can affect the ability to conduct prescribed burns and pursue other preventative action,” the center said.