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Wildfire ignition risks rise as temperatures climb

Posted On: Jun. 22, 2021 7:00 AM CST


Extreme heat and drought conditions across the western United States are increasing concerns about a dangerous wildfire season ahead, but there are steps businesses can take to reduce losses.

Some 88% of the land area of Western states is in drought conditions, while more than 50% is in extreme or exceptional drought, according to the U.S. Drought Monitor, a collaboration between the National Drought Mitigation Center at the University of Nebraska-Lincoln, the U.S. Department of Agriculture and the National Oceanic and Atmospheric Administration.

Long-term extreme drought typically increases the risks of fire in forested regions, even though dry conditions can limit growth of vegetation in grasslands potentially reducing the risk in those areas, experts say.

Naturally occurring wildfires are most frequently caused by lightning, while man-made ignitions include power lines and utilities, not properly extinguished campfires, sparks from dragging chains on vehicle trailers, cigarettes, and fireworks.

Among natural ignition sources, lightning is of greatest concern, said Robyn Heffernan, national fire weather science and dissemination meteorologist at NOAA National Weather Service in Boise, Idaho.

The Southwest monsoon season, which began June 15, typically includes a good amount of lightning, she said. Monsoon rains can decrease fire activity in the Southwest, but in adjacent areas, such as farther north into the Great Basin, the Rockies and along the west coast, lightning can ignite new fires, Ms. Heffernan said.

Drought is only one component of wildfire risk, and sources of ignition, as well as the weather at the time of ignition, are critical, said Philip Cunningham, senior scientist at catastrophe modeler AIR Worldwide Corp. in Boston.

Wildfires caused by man-made ignitions typically outnumber wildfires from natural ignitions, but in 2020 almost all of the big fires were caused by lightning, he said.

California, in particular, saw unusually large amounts of dry lightning last August that ignited hundreds of fires, he said. 

The August Complex fire, started by lightning strikes in August 2020, was the largest in California’s history based on acres burned, according to the California Department of Forestry and Fire Protection. It spread across 1 million acres and affected seven counties.

Unlike man-made ignitions, which tend to occur in more populous areas, fires ignited by lightning often start in remote areas, which means they can grow large before they are spotted, Mr. Cunningham said. 

Maintaining adequate defensible space around building structures is critical to decreasing the likelihood of loss, experts say.

Business owners should keep properties well-maintained, clear brush and cut back trees around the sides of buildings or roofs that can potentially ignite, Mr. Cunningham said. Keeping roofs clear of debris is especially important as winds can blow embers hundreds of meters or even miles, igniting materials, he said.

The best thing businesses can do is control damage to their sites, assuming a wildfire has ignited and is headed toward their facility, said Katherine Klosowski, global vice president of natural hazards and structures at FM Global, in Johnston, Rhode Island.

Passive protection methods for industrial buildings include using non-combustible construction, such as masonry walls, concrete block, brick walls or even an insulated metal panel of low combustibility, Ms. Klosowski said.

“Safeguarding the walls and roof of a facility using non-combustible materials is first and foremost the most important thing,” she said.

Designing buildings without gaps under doors or around windows and installing covers over air-conditioner vents help prevent sparks from embers that winds blow onto an industrial facility from a distance, Ms. Klosowski said.

Automatic protection such as sprinklers installed on the exterior as well as inside buildings can minimize damage as well.

Businesses can install lightning protection rods on a roof, or highest point of a facility, Ms. Klosowski said. If lightning strikes the structure, it will hit the rod and bring the charge down to the ground, she said. 

Building in layers of protection is important, she said. “Big losses often have a series of events that go wrong. … If you can break that cycle, you’ve got a better chance of safeguarding the business,” she said.

The cost of lightning-caused claims skyrocketed due to 2020’s wildfires, according to a spokeswoman at the Insurance Information Institute in New York

“The average cost per lightning claim in California was $217,555 last year, while the national average for this type of claim was nearly $29,000 in 2020,” she said.

The severity of wildfires means that homes and other structures are often destroyed rather than partially damaged, which pushes the claims value higher, the I.I.I. spokeswoman said. The likelihood of total loss is also increased if a wildfire spreads quickly in an area that is hard to access, she said.

Rebuilding can be costly because the price of materials such as lumber is higher and supply chain issues from the pandemic have contributed to rising construction costs, the I.I.I. spokeswoman said.