22 august 2020

What Makes California's Current Major Wildfires So Unusual

Dry lightning, extreme heat, and Covid-19 are all shaping California’s efforts to contain massive, deadly blazes.

By Umair Irfan, Vox, via Reader Supported News, 22 August 2020

stunning, sudden surge of wildfires is burning through California, threatening towns and sending choking smoke over major cities and across much of the United States. It’s creating an epic compounding disaster whose ingredients have been brewing for years.

Fire officials have grouped some of the smaller fires in an area into complexes to coordinate their response. The largest of these is the SCU Lightning Complex. It’s burned 229,000 acres as of Friday morning across parts of the southern San Francisco Bay Area, including Santa Clara and Alameda counties. The SCU Lightning Complex is now 10 percent contained, but officials expect “critical rates of spread” as winds pick up.

To the north, the LNU Lighting Complex near Napa has killed at least four people, burned more than 219,000 acres, and destroyed or damaged 600 structures. Thousands were forced to evacuate. The fire was 7 percent contained as of Friday morning, and officials anticipate the flames will spread further.

These are just two of dozens of large fires currently raging across the Golden State. Together, all these fires have burned close to 600,000 acres in California in just under a week.

It’s not just the size of the fires that’s so concerning; some of the blazes are in coastal areas that don’t burn very often, threatening the state’s iconic redwoods.

The blazes were ignited by a massive dry lightning storm earlier this week over many parts of the state but concentrated in the San Francisco Bay Area.

“We had close to 11,000 strikes in a matter of three days,” said Brice Bennett, a spokesperson for the California Department of Forestry and Fire Protection (Cal Fire). “With an already-warm weather pattern and very, very dry conditions here in California, with those lightning strikes coming through, over 367 new fires were started.”

Smoke, soot, and ash from the fires also shrouded Northern California in the dirtiest air in the world at several points during the week.

Wildfires are nothing new for Californians, and many are wearily growing accustomed to the heat, smoke, and evacuations as fires reignite in areas torched in the recent past. But this week’s blazes stand out for their scale, timing, locations, and intensity, even among recent record-breaking fire seasons.

And the wildfires are just one of several harrowing disasters afflicting California right now. The state has been scorched by a record-breaking heat wave, with several days in a row of temperatures reaching triple digits in some places, even at night. Temperatures in Death Valley topped 130 degrees Fahrenheit. That heat led to rolling blackouts as utilities struggled to meet cooling demand.

All the while, the Covid-19 pandemic is raging throughout the state, with the number of new cases increasing over the past two weeks and making the already difficult task of controlling wildfires even harder.

Here are the factors that have fueled the recent fires and are now complicating the efforts to control them.

Extreme heat, strange storms, and climate change set the stage for California’s fires

The lightning storm around the San Francisco Bay Area that sparked many of the current California fires was a rare event.

“The last time we had something like this was over a decade ago, actually,” said Bennett. The fact that lightning started these fires is also noteworthy. The vast majority of wildfires in California are ignited from human sources — powerlines, arson, neglected campfires, and so on.

But the fires wouldn’t have been so bad were it not also for the extreme heat that’s been baking the state for weeks.

“This is a big, big prolonged heat wave characterized not only by hot daytime temperatures, but also record warm overnight temperatures, and an unusual amount of humidity,” said Daniel Swain, a climate scientist at the University of California Los Angeles and a researcher at the National Center for Atmospheric Research. “It turns out increased humidity plays a role in why there are so many fires right now.”

A decaying tropical storm earlier this month in the eastern Pacific Ocean sent a plume of moisture over California. Amid the scorching heat, the moisture formed clouds that generated immense amounts of wind, thunder, and lightning, but very little rain. “The humidity was high enough to produce these thunderstorms, but not high enough to produce significant flooding rainfall that would mitigate fire risk,” Swain said.

Much of California’s vegetation was also parched and primed to burn, and concerns that this would be an exceptionally bad fire year started to emerge in February as the state emerged from one of its driest winters on record. This was then followed by an abnormally hot spring. “There were a number of unusually significant early season heat waves this spring both in northern and in southern California,” Swain said.

And California is now experiencing the impacts of climate change, which is manifesting in fires. The weather in California is becoming more volatile. Temperatures are also rising, which is causing the state’s forests, grasslands, and chaparral to dry out even more. Already, the state has suffered millions of dead trees stemming from years of drought and pests like pine beetles. More heat could stress these ecosystems even further.

“It’s not just how hot are the heat waves; it’s how hot is it the rest of the time,” Swain said. “What really matters is the sustained warming and drying over seasons and years.”

Some of California’s current fires are in areas that don’t regularly burn

It’s important to remember that fires are a normal part of the ecology in California, from the coniferous forests in the Sierra Nevada to the chaparral shrubland in the south. Periodic blazes clear out decaying vegetation, restore nutrients to the soil, and help plants germinate.

Humans, however, continue to make California’s wildfires worse at every step. By suppressing naturally occurring fires, fuel has accumulated in forests and shrublands, increasing the danger when fires do ignite. People are also building closer to areas that are prone to burn. That increases the likelihood of starting fires and raises the blazes’ damage toll. People have also introduced invasive plant species like Eucalyptus trees, which have spread throughout California and readily ignite. And burning fossil fuels emits greenhouse gases that are warming the planet, increasing the amount of vegetation that can burn.

Even with this backdrop, the some of the fires in California stand out because they are raging in places that don’t burn very often.

“I think what’s key to understand is that different parts of California have very different normal fire seasons,” said Crystal Kolden, an assistant professor of fire science at the University of California Merced. “And that’s in part because California is such a big state. It has really variable topography and different vegetation or ecosystems across the state.”

Some of the more striking fires right now are in California’s coastal redwood forests. On Thursday, offices buildings at Big Basin Redwoods State Park burned down, and fires damaged some of the park’s stalwart trees. Some redwoods in the park are still smoldering as they burn from the inside.

Because coastal forests are under the influence of marine weather systems, they are much cooler and retain more moisture than the pine forests of the Sierra Nevada and other inland areas. The coastal forests do burn periodically and are home to many species that have adapted to fire, but they rarely ignite during the summer.

That they’re on fire now is remarkable, a product of high atmospheric pressure over the area that allowed heat to accumulate and overwhelm the cooling effect from the ocean. “Those coastal areas are incredibly dry, incredibly hot relative to normal, and that arid and hot condition had this potential to have really explosive fires,” Kolden said.

Covid-19 is adding a wallop to California’s fires

The Covid-19 pandemic has rattled every part of society, and firefighting efforts are not immune. “It has definitely has affected our response, primarily in our inmate fire crews,” Bennett said.

California often relies on prison labor to bolster its firefighting efforts, with almost 200 inmate fire crews. Inmates are paid between $2 and $5 a day, plus $1 per hour when fighting a fire. But with severe Covid-19 prison outbreaks in the state, some inmates were released to relieve overcrowding. Others were hampered by infections, and many remain under quarantine. The number of available inmate fire crews has been nearly halved.

Anticipating a severe fire season, state officials did line up an additional 800 seasonal firefighters, but they have to take additional precautions. Fire crews are essentially staying in small bubbles, where they live and work with just each other, to help limit coronavirus transmission.

At base camps where fire crews rest and refuel, officials have designated more space for workers to maintain social distance.

The state is also facing a budget crunch, with the economic slowdown because of pandemic. That’s led some fire prevention maintenance measures — like clearing dry grass away from roads and buildings — to languish.
As for the Californians fleeing the fires, Covid-19 has made it harder to coordinate evacuations and shelters. The declining air quality from the wildfires is also a threat to people with Covid-19, since exposure to air pollution can damage airways and make people more susceptible to respiratory infection. And extreme heat also worsens the public health impact of Covid-19 as people spend more time in enclosed spaces together to avoid the heat.

And the current round of blazes may take weeks to extinguish, raising the concern that stiff autumn winds — the Santa Ana winds in the south and the Diablo winds in the north — may spread the flames again.

California is facing yet more high temperatures through the weekend and forecasters warn that more dry lightning may be in store.

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