Canadian wildfire smoke caused local ‘global dimming’ across the US

The skies above the northeastern US were apocalyptic during the summer of 2023. The smoke from record-breaking wildfires throughout Canada caused catastrophic air quality and even led to unprecedented cooling in the New York and New Jersey metropolitan areas, according to a newly published study.

Researchers from New Jersey’s Rutgers University found the smoke caused “global dimming,” or the decline in sunlight reaching Earth’s surface, in the cities. The effect dropped the region’s temperatures by 3 degrees Celsuius, or 5.4 degrees Fahrenheit.

The temperature drop also trapped air pollutants near ground level. Smoke particles and other particulate matter from the wildfires absorbed and scattered the sun’s light over the cities. The “smoky umbrella” blocked solar radiation and cooled the areas below, limiting natural air circulation and increasing exposure to harmful airborne contaminants.

“This study documents for the first time the effect of wildfire nanoparticles on the microclimate of megacities,” Philip Demokritou, the study’s senior author and professor of nanoscience and environmental bioengineering at Rutgers, said in a press release. “Such ambient air temperature reductions may exacerbate the urban heat island effect and limit the natural ventilation of megacities, exacerbating the exposure to air pollution.”

Smoke map, Northeast U.S., by fire.airnow.gov
Smoke map, Northeast U.S., by fire.airnow.gov

The total particulate matter in New York City’s skies was more than three times higher than the Environmental Protection Agency’s guidelines, and eight times higher than the World Health Organization’s recommendation, researchers said. The air pollution reportedly contributed to health impacts across the region, according to epidemiological studies in the cities that showed increases in emergency hospital visits and the exacerbation of asthma.

A companion paper from the same research team also found that 9.2 mg of smoke particles were deposited in people’s lungs in the region during the event. The particles reduced the viability of immune cells in people’s lungs, increasing vulnerability to respiratory infections.

“Wildfire events have increased in frequency and intensity dramatically due to extreme drought and heat and now affect even the Northeast U.S.,” Demokritou said. “This was the first event of this scale in the region, but it probably won’t be the last.”

Click here to read the full study.

Los Angeles-style wildfires will likely hit mid-Missouri

Mid-Missouri communities are ripe for an LA-style wildfire disaster, and experts have rung the alarm bells for years. Communities near the Lake of the Ozarks, in particular, have a higher chance of wildfires igniting than nearly every other community in the nation, and the likelihood is only expected to increase in the years to come.

Ground zero for severe urban wildfire concerns in Missouri is Lebanon. The city’s wildfire likelihood is higher than 84% of communities in the nation, and 99% higher than other communities in Missouri, according to the US Forest Service’s “Wildfire Risk to Communities” dataset.

The cause is, in part, due to the region’s woody encroachment of eastern red cedar and other non-fire-tolerant vegetation, driven by a more-than-century-long absence of fire on Missouri’s landscape. The fire suppression regime, however, is slowly being reversed throughout the state. A Prescribed Burn Association movement is working to reintroduce “good” fire to Missouri through prescribed low-intensity fires.

Federal and state agencies largely can’t burn in the state because of the wide-sweeping privatization of land. Around 93% of Missouri’s 44.6 million acres is privately owned, meaning officials have to convince landowners that fire is both good and necessary on their land before a prescribed fire can be set.

That convincing is done on the neighborhood level by Prescribed Burn Associations, or PBAs, in the state overseen by the Missouri Prescribed Fire Council. The most consequential of these associations is the Niangua Basin Prescribed Burn Association, which oversees Missouri’s most wildfire-prone counties of Camden, Dallas, Hickory, and Laclede.

“It’s become an organization of learning and neighbors helping neighbors,” Lance Dunbar, who runs the PBA, said. “The PBAs were the genesis of the Missouri Department of Conservation to help organize prescribed burning. They’re now in almost every county in the state.”

Click here to read the full article.

Timeline of LA’s historic wildfires outlined in new report

What started as a wildland fire quickly catalyzed into a widespread urban wildfire in Los Angeles on Jan. 7. In the wake of the tragedy, researchers are understanding more about just what fueled the conflagration.

A new report from the Insurance Institute for Business & Home Safety outlines the timeline of both the Palisades and Eaton fires. Institute researchers also entered the community in the days following the destruction and uncovered what types of homes were worst-hit by the fires, and which were more fire resistant.

The Palisades Fire ignited near Skull Rock in the Summit neighborhood at 10:30 a.m., when gusts were reaching up to 60 mph, relative humidity was falling, and severe Santa Ana winds created a highly volatile environment for rapid fire spread. The fire quickly spread downhill and eastward, spreading 771 acres in 4 hours, 2,920 acres in 8 hours, and 15,832 acres in nearly 27 hours, which accounted for 70% of the fire’s total growth, despite it going on to burn for 43 more days. The Palisades Fire was fully contained on February 20 after burning over 23,000 acres, destroying 6,833 structures, and claiming 12 lives.

The Eaton Fire ignited in the Eaton Canyon area of the San Gabriel Mountains at around 6:20 p.m., around eight hours after the Palisades Fire began. At that time, peak gusts surpassed 60 mph, sustained winds exceeded 40 mph, and relative humidity had dropped to around 10%, creating extreme fire weather conditions. Just 16 hours after igniting, the fire had grown to over 10,000 acres. Although the fire continued burning for 42 more days, its initial 24-hour growth of over 13,600 acres would be 96% of its final size. The fire was fully contained on Feb. 20 after burning over 14,000 acres, destroying 9,418 structures, and claiming 17 lives.

Flames from burning tightly spaced buildings only worsened the fires’ spread, according to the report. Each home ignition generated short-range and ground-traveling embers, further amplifying the fire, specifically in downtown Altadena and Pacific Palisades. Fire-resistant building materials, however, reduced damage severity and interrupted the chain of conflagration.

Click here to read the full report.

Natural Hazards Research Australia is holding a public webinar on the report at 11:30 a.m. AEST on April 16 (9:30 p.m. ET on April 15). Click here to register.

 

War sparked Ukraine’s worst wildfire year in history

New research published by the European Union found Russia’s ongoing invasion has worsened environmental challenges in Ukraine, including ongoing wildfire trends.

The risk of large forest fires has “significantly increased” in the nation. The country’s worst wildfire years happened over the last 5 years, by far the worst of which was in 2024, the EU study said.

“The ongoing conflict in Ukraine has severely hampered efforts to prevent and control large fires,” researchers said. “Restrictions on public access to forests and natural landscapes, introduced by Martial Law, have blocked fire prevention activities such as patrolling and establishing firebreaks.”

Numerous other wartime impacts have caused issues for wildfire mitigation, including the enlistment of firefighters and the destruction of fire management infrastructure.

 

Credit: Publications Office of the European Union

Wildfires account for between 45% and 65% of forest cover loss in the nation annually, cover loss that has worsened since the invasion began.

The spike was driven by more frequent heat waves, droughts, and windy weather, which Ukraine’s forest management and emergency response systems were not prepared to deal with.

“Explosive remnants and other potential causes further increase the risk of wildfires, and reallocation of fire-fighting resources makes it more difficult to prevent or control large fires,” the study said. “Climate change also contributed to forest cover loss by significantly increasing the risk of large forest fires, especially in the last five years.”

The largest forest fires in the nation happened in the Eastern and Southern regions, specifically Kharkiv, Luhansk, Donetsk, and Kherson oblasts. The fires tended to cluster along the front lines of military, underscoring the close relationship between conflict and forest fires.

Click here for the full study.

Credit: Publications Office of the European Union

Early Alaska wildfire season has quick snowmelt to blame

Teams competing in Alaska’s famous Iditarod Sled Dog Race know to be prepared for blizzards, sub-zero temperatures, and gale-force winds. Competitors in the 2025 race, however, were forced to add wildfires to their already treacherous list of extreme conditions in the race.

The race was moved to its northern route in early March after the Alaska Division of Forestry & Fire Protection declared an early wildland fire season, requiring burn permits starting March 17 instead of April 1, according to the Bureau of Land Management Alaska Fire Service.

Alaska’s most populous areas in the Kenai Peninsula and the Mat-Su Valley had two fires spread in snow-free grasses before the Iditarod’s 1st place racer crossed the finish line.

“The risk of human-caused fires has become evident, with at least 17 requiring a response as of April 6,” the Service said. “Most were the result of negligent burning, emphasizing the critical importance of ensuring that burn piles are monitored, keeping fire tools on hand, and never leaving a fire unattended.”

The state’s official first wildfire of the year was the result of an escaped burn set by a Mat-Su resident who was later found to be in violation of Alaska law regarding the “uncontrolled spread of fire,” according to the region’s local newspaper.

Credit: Alaska Division of Forestry and Fire Protection

Early snowmelt is largely to blame for increased wildfire risk throughout the state, according to recently published research from the University of Alaska Fairbanks. Each of the state’s largest and most extreme wildfire seasons was preceded by early snowoff, accompanied by large-scale climate patterns that keep a high pressure over the state.

“Three of Alaska’s four largest wildfire seasons occurred during years with earlier than average snowoff dates,” the researchers found. Many Alaskans will remember these seasons. In 2004, 6 million acres burned, and another 4.4 million acres burned the next year. In 2015, 5.1 million acres burned. Years with early snowoff were also responsible for more than half of the historical area burned in Alaska.”

Read the full press release regarding the research here.

New wildland firefighter pay scales released by US feds

The U.S. Office of Personnel Management recently released new local pay scales for the nation’s wildland firefighters after lawmakers passed the Wildland Firefighter Payment Protection Act last month.

Lawmakers passed the act as part of the 2025 Department of the Interior, Environment, and Related Agencies Appropriations Act when they narrowly avoided a government shutdown on March 14. The act increases wildland firefighters’ special hourly base rates depending on an employee’s GS, or General Schedule, level. The increases include: