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More than 1.4 million acres have burned across California.
Gov. Gavin Newsom of California on Monday addressed a state besieged by wildfires of staggering scale and spread, assuring residents that “we’ve deployed every resource at our disposal” as the number of active fires grew to 625.
And even though a new front of lightning storms was less severe than expected, Mr. Newsom emphasized that almost 300 lightning strikes overnight had sparked 10 new fires — every one of which could have become a new threat.
More than 7,000 fires have chewed through 1.4 million acres this year, making this fire season one of the most active ever. By this point in 2019, 4,292 fires had burned 56,000 acres across the state, Mr. Newsom said.
Tens of thousands of firefighters from across California and states from as far away as Kansas have been enlisted to help contain the blazes, which have been linked to seven deaths.
Hundreds of fire engines have been sent out across a huge portion of the state — including to towering forests that are being charred by fires “the likes of which haven’t been seen in modern recorded history,” Mr. Newsom said.
But climate experts warned that the activity so early in the year and across such varied landscapes offers a preview of a fire and flood cycle that is likely to keep getting worse.
“I’m running out of superlatives,” said Daniel Swain, a climate scientist with the Institute of the Environment and Sustainability at the University of California, Los Angeles.
Mr. Swain said he expected this year to have the greatest number of acres burned under California’s modern fire suppression regimen.
More troubling, he said, was that fires have burned ecosystems where there were not typically wildfires. Fire is common in expanses of dry grass and chaparral, particularly following a dry winter like the one this year.
But burning Joshua trees, redwoods and coniferous forests? That is alarming, he said.
“I actually don’t know of any vegetation type that is not on fire in California,” he said.
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Firefighters have made progress against the biggest fires.
The largest group of fires tearing across Northern California, the L.N.U. Lightning Complex, which stretches across Napa and surrounding counties, has grown to 350,000 acres but is now 22 percent contained.
Shana Jones, the chief for Cal Fire’s Sonoma-Lake-Napa unit, said at a news conference on Monday that firefighters were “making good progress” on the complex. But she added that given the size and complexity, “it’s going to take time to put this fire out.”
The S.C.U. Lightning Complex, which has burned more than 347,000 acres to the east of San Jose, was 10 percent contained on Monday.
Though the storm system brought fresh lightning strikes, it also carried moisture that helped diminish some of the fires, including the C.Z.U. Lightning Complex north of Santa Cruz, which has grown to 78,000 acres but is now 13 percent contained.
“Mother Nature has helped us quite a bit,” Billy See, a Cal Fire assistant chief, said.
California’s redwoods can withstand fire, but another threat looms: climate change.
Among the hundreds of fires raging in California, one has drawn special attention because it has burned through a state park that is home to more than 4,000 acres of the state’s iconic old-growth redwood trees.
Big Basin State Park, about 40 miles south of San Francisco, has been closed since the middle of last week because of the fire, the C.Z.U. Lightning Complex. While most if not all of the park’s structures have been destroyed, little is known yet about damage to the coast redwoods, the species that grows at Big Basin and other parts of California within about 30 miles of the ocean, where they take advantage of the foggy, Mediterranean climate.
But Matt Ritter, a botanist at California Polytechnic State University in San Luis Obispo and director of the school’s plant conservatory, says there is probably little to be worried about.
“They’re ridiculously good at coping with fire,” Dr. Ritter said. Some of the redwoods are a thousand years old or older, he said, “and nothing lives for a thousand years in California without surviving many, many fires.”
Wildfire can sweep through a forest and not kill any of the tissue in a redwood’s trunk, where most of the growth occurs. In a mature redwood this tissue, called the cambium, is protected by up to two feet of bark. The bark is “insanely thick,” Dr. Ritter said, and contains compounds that are naturally fire-resistant.
“California has been burning for about three to five million years,” he said. “Trees have evolved in a fire situation to be protected against it.”
The trees, which can reach 200 feet or higher, also have few limbs within the first 80 to 100 feet. So other trees that catch fire — oaks, madrones or other species, or younger, smaller redwoods — may burn but the flames are unlikely to reach the redwoods’ canopy.
Fire in a redwood grove actually has benefits for reproduction, as the trees that do burn add nutrients to the soil. “Only after a fire do you get really good germination of seeds,” Dr. Ritter said. Over the years at Big Basin and other areas with redwoods, he said, controlled burns have been done for this reason — to encourage growth of new trees.
Large redwoods occasionally do die in a fire, Dr. Ritter said, but that usually occurs when a smaller burning tree falls against it and the redwood’s bark smolders and is eventually breached.
What has harmed the state’s redwoods historically has been logging, Dr. Ritter said. That was outlawed decades ago. The new threat now is from global warming and its potential to alter the foggy conditions in which redwoods thrive.
“These trees don’t have to worry about fire as much as human-caused climate change,” he said.
Concerns over poor air quality have closed schools and parks.
Smoke-filled air has been a persistent problem for much of the Bay Area, leading to repeated health warnings, interruptions to school reopenings and further threats to businesses already struggling from coronavirus-related closures.
In Concord, the air quality index reached 240 overnight, surging into the “very unhealthy” range, a point at which health experts caution everyone against going outside. By Monday morning, the reading was lower, around 157, which is still considered unhealthy for the general population.
The air quality index goes up to 500, but any reading above 100 is considered unhealthy for sensitive groups. Those with respiratory illnesses like asthma are particularly vulnerable, as are children and the elderly.
In Vallejo, the air quality hovered around 160 after worsening overnight. Air quality around the Bay Area has fluctuated as the fires burn nearby, but readings in recent days have regularly shown that it is unhealthy for people to spend time outside their homes.
The Oakland Zoo, which reopened a few weeks ago after a four-month closure that nearly forced it to shut down permanently, closed its doors again this week because of bad air quality.
Dozens of state parks and beaches have also closed, some Bay Area schools have canceled classes, and coronavirus testing sites have temporarily closed or relocated.
San Jose State University, which was set to reopen for in-person classes last Wednesday, has closed its campus through Tuesday because of concerns about air quality, moving all of its instruction online.
“We understand this is not an ideal start to an already unprecedented fall semester,” wrote Vincent Del Casino, Jr., the provost and senior vice president for academic affairs.
Some who are seeking shelter with friends worry about exposing them to the virus.
For families who might ordinarily flee to the homes of relatives or close friends, worries about the virus have complicated those decisions.
Chelsea Sterrett and her husband, both high school teachers, were in the midst of their first week of online instruction when they were ordered to evacuate, as the River Fire, south of Salinas, approached last week.
So they packed up their three children (ages 7, 5 and 1) and a dog, and left home to stay with family friends whom they hadn’t seen in months because of the pandemic.
“The immediate crisis of the fire was bigger than our concerns about Covid,” Ms. Sterrett wrote.
Kevin Susco wrote in an email late last week that his daughter-in-law asked on Tuesday if she and her son, who were under an evacuation warning in Boulder Creek, could stay with him and his wife in Palo Alto.
Their son, he said, is an Army Reservist currently in Kuwait.
“We’ve been together only briefly since the pandemic, because my wife and I are both in our sixties, and we take the threat from the virus seriously,” he wrote in an email. “But we didn’t think about it too much before we said, sure, come over if you need to evacuate.”
Deborah Meltzer, 67, said in an email that she’s one of a growing number of baby boomers who are live-in caregivers to aging parents — in her case, her 100-year-old father.
She lives in Elk Grove, where smoke has filled the air and the dangers, both from the fires and the poor air, are constantly on her mind.
“Quite frankly, I am not sure what I would do or where I would take my dad in the event of an evacuation,” she said.
Smoke and fire in Napa is almost business as usual.
In Napa County, some local residents seemed unfazed by the wildfires over the weekend, expressing a weary acceptance. They’re used to this.
“It’s the new normal — what next?” said Bulah Cartwright, the manager of Inti, a clothing and jewelry store in Napa. “We’ve had earthquakes, fires, flooding. It’s exhausting, but we’ll get through. We’ve gotten through worse.”
Wine country residents are well aware of the perils posed by wildfires. The Tubbs fire swept through the area in 2017, devastating the town of Santa Rosa and killing 22 people. Last year, the Kincade Fire destroyed hundreds of buildings, including much of the Soda Rock winery in Healdsburg.
But shop owners and residents said on Saturday that they were more concerned that the smoke and flames might drive away the tourists upon whom the region relies.
“Business has been slow, obviously,” said Thea Witsil, the owner of Wildcat Vintage Clothing in Napa. It might seem busy on a Saturday, she said, but “come here in the middle of the week, it’s a completely different story.”
Many tourists, though, were also undeterred by the persistent fumes that blew through Napa Valley towns and partially obscured nearby hills.
“We feel bad doing all this nice stuff when people are having to evacuate and lose their homes, but at the same time, if we cancel, we leave a lot of them, as employees, in the dust,” said Daniel, who was visiting Yountville from Los Angeles for his birthday and declined to provide his last name. “I feel like if Covid’s taught us anything, you have got to try to enjoy things and work around life as you can.”
Reporting was contributed by Kellen Browning, Jill Cowan, Jacey Fortin, Henry Fountain and Lucy Tompkins.