While many Californians are praying for enough rain to slow the spread of the 6,078 fires that have burned 977,932 acres across the state this summer, firefighters and climatologists recognize that the heavy rains are a big reason why this fire season is nearly three times larger than the 2023 total.
After Northern California’s brutal summer fires, Southern California has been exploding with fires this month, including the massive Park Fire, now the fourth-largest wildfire in state history. The Line Fire in San Bernardino County, northeast of Los Angeles, has grown to 35,000 acres in just over a week since it started, threatening tens of thousands of homes and forcing thousands of residents to evacuate.
There were 5,053 people Wildfires burned 253,755 acres as of September 11, 2023. This year, about 1,000 additional wildfires have burned 3.85 times more acres so far this year. Much of the increase can be attributed to what climatologists call “weather whiplash.”
Over the past four years, California’s weather has shifted from a drought from 2020 to 2022 to two extremely wet years in 2023 and early 2024. That moisture has fueled the proliferation of what are known as microfuels: grasses, small shrubs, mosses, and sticks that grow quickly and easily catch fire.
Firefighters call it one-hour fuel because it can dry out to a flammable state in just one hour in a dry, sunny environment.
Climate change fueled last year’s wildfires, some worse than others.
Grassland ecosystems are more vulnerable than trees to climate change in recent years.
“Forests don’t come and go, grow or die based on the difference between wet and dry years,” says Daniel Swain, a climate scientist at the University of California, Los Angeles. “But if you have a grassland ecosystem, it can respond quite significantly to changes from year to year.”
In dry years, the grasslands look like dried-out lawns, but in wet years, grasses can grow waist-high or head-high. When hot, dry weather returns, the heavy fuel grasses harden quickly, ignite easily, and spread fires across the landscape much faster than wildfires, reaching trees and structures.
While wet winters and atmospheric rivers over the past two years have spurred grass growth, record-breaking summer heat has turned vast savannas into fuel.
“We added more fuel to the fire and then essentially dried it in a kiln at record heat,” Swain said.
The Park Fire, which burned 429,603 acres in California this summer, is a prime example of how grass can fuel the largest and most destructive wildfire in the West. The fire started in isolated grasslands and shrublands, and much of the burned acreage was in a microfuel ecosystem. Driven by strong winds, the fire moved into denser vegetation and forests, where heavier biomass can provide much more energy to the fire. While many ground fires burn slowly and low on the forest floor, a fire with enough fuel can easily spread flames up to 100 feet in the canopy, creating crown fires.
“It’s the worst of both worlds. We get very rich grass, and we also get very dry forest,” Swain said. “If you have a wet winter, and then a record-breaking heat wave, and then fall, you can have what we’re seeing now.”
A fast grass fire can ignite wooden fence railings, decks, landscaping, and siding, spreading the fire throughout the community. Many homeowners who live in areas surrounded by grass don’t realize that their property is at risk from wildfires in the same way as a home in the woods, but experts advise that they should prepare their property just as much as anyone who has a home in the woods.
The danger comes from the speed of the fire. Grasslands burn quickly. They often burn close to communities, and when pushed by strong winds, the fires can spread quickly, potentially using structures as new fuel.
Between Christmas and New Year’s Day 2021, a rare winter prairie fire erupted into the most destructive fire in Colorado history, in just two days. The Marshall Fire burned 1,084 homes and seven commercial buildings.
Ralph Bloomers, Green Oregon’s community fire safety director, said about 80 percent of home losses from wildfires occur in grasslands.
“Fire is here to stay. Fire is inevitable,” Bloomer said. “The problem is not the fires, it’s the vulnerability of communities built on fire plains, because we can’t eliminate fire in the fire-prone, fire-adapted landscapes of the West. That’s a natural reality.”
no way study In her co-authored paper, Bloomer emphasized improving the resilience of at-risk communities: modifying structures and landscapes around communities can reduce the likelihood of wildfires starting and reduce the likelihood of ignition when fires are difficult to control.
“Fires are just there. Fires are inevitable. The problem is not the fires, but the vulnerability of communities built on fire plains.”
Forest dwellers have long been advised to build homes with noncombustible roofs that are less likely to catch fire, to clear bark mulch, brush and wood piles from their homes, and to reduce the density of flammable plants around their homes. While many residents whose homes are surrounded only by grassland and shrubland may think their homes are less at risk, Bloomers says they should be equally diligent in making their properties resilient to wildfire. Studies show that most home losses nationwide occur in fast-burning grassland and shrubland ecosystems. People should be more vigilant about starting fires in dry grassland, for example, by not using machinery that can start a fire in dry grassland.
In addition to community preparedness, the public should be aware that “people and human activity are responsible for most vegetation fires. I would say more than 90 percent of vegetation fires. [Cal Fire’s] “Fire is caused by people and our actions,” said Isaac Sanchez, deputy chief of communications for the California Fire Marshal’s Office.
2023 study We found that wildfire-related structural losses are not simply a function of the area burned. Instead, 76% of all structural losses in the West are due to unplanned human-caused ignitions. Unlike the historically destructive Marshall Fire, which burned 6,080 acres, the Park Fire destroyed 375 fewer structures while burning over 70 times more acres. Thousands of personnel were on the scene, and as of September 11, the fire was 99% contained.
With destructive fires from all fuel types becoming more frequent, “we can’t afford to be a careless firefighter early in the season and burden our firefighting response,” Bloemers said.
He said more work was needed to reduce wildfire intensity and losses associated with “weather volatility” in the coming years.
