WATCH: Jet drops fire retardant liquid on raging California wildfire
Some 14 000 firefighters, including inmate volunteers, are battling 18 major blazes burning thousands of square kilometres throughout California with aircraft, assorted vehicles and picks and shovels.
They take aim at the biggest wildfires in two ways and in much of the same way the Department of Forestry and Fire Protection has for decades. They'll go at it directly with water and retardant where they can.
And when they can't take that direct approach, firefighters retreat to a ridge, wide road or stream where they use bulldozers to cut a "fire line". There they'll wait for the blaze to come to them while lighting "backfires" to clear vegetation between the fire line and the approaching blaze.
Experts say whichever approach Cal Fire takes, California firefighters are often more aggressive in trying to extinguish wildfires than those in other less-populated states. That's because California wildfires are increasingly threatening sprawling urban areas.
"Cal Fire is really an urban firefighter service in the woods," said Arizona State University life sciences professor Stephen Pyne, a wildfire management expert.
Cal Fire spokesperson Scott McLean said firefighters use both approaches to battle the large blazes, including the growing twin fires about 160km north of San Francisco.
McLean said firefighters are using the direct approach to prevent the fires from reaching urban areas along Clear Lake while retreating in national forests "and letting the fire come to us".
Those two fires grew to a combined 1 148km2 to become the state's largest wildfire.
McLean and fire experts say it's impossible to surround a fire that large, especially with 17 other major fires requiring attention in the state.
"We are building lines. Picking and choosing where we think we can take a stand," McLean said. "Attacking it where we can and waiting and letting it come to us when appropriate."
McLean said firefighters are using direct means to prevent the twin fires from reaching evacuated urban areas on the east side of Clear Lake. At the same time, firefighters have pulled back in the uninhabited national forests to the north, where they have cut fire lines and are employing indirect methods.
Experts say the best way to fight these destructive wildfires is to prevent them in the first place when building homes and other buildings.
"It's the embers, not the fire itself, that destroy most homes," said Steve Conboy, a construction expert whose company develops fire-resistant chemicals to apply to wood.
In the meantime, Gov. Jerry Brown and other state officials warned that the state is expected to endure record-breaking wildfires going forward. Drought, warmer weather and other factors have combined to start wildfire season sooner and make the blazes more destructive.
"We're in uncharted territory," the governor said last week. "Since civilization emerged 10 000 years ago, we haven't had this kind of heat condition, and it's going to continue getting worse. That's the way it is."
Firefighting costs have more than tripled from $242m in the 2013 fiscal year to $773m in the 2018 fiscal year that ended June 30, according to Cal Fire.
"In past decades, we may have seen a fire that we're seeing now in August or September," Ca Fire Director Ken Pimlott said during a press conference last week. "We are routinely now seeing fires reach 100 000 acres several times in one month and it's only July, so we have a long way to go in this fire season, and as we saw last year fire season can go right up through December."
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