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  • Lightning strikes and gusty winds have led to hundreds of fires across California, California Governor Gavin Newsom said on Wednesday.
  • The three biggest blazes have already spread across more than 40,000 hectares, destroying property and forcing thousands of evacuations. 
  • Climate change is increasing the severity of wildfire season in California. 
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Firefighters are battling over 360 blazes across California on Wednesday after nearly 11,000 bolts of lightning struck the state in just 72 hours.

Gov. Gavin Newsom declared a statewide emergency on Tuesday, noting that while the lightning likely ignited many of the fires, gusty winds and a statewide heatwave have exacerbated them.

"We are deploying every resource available to keep communities safe as California battles fires across the state during these extreme conditions," Newsom said.

Of the 367 total fires in California, the state has around 23 complex fires, the term for multiple blazes in one region, Newsom said. The largest and fastest-moving of those tore through Northern California on Tuesday and Wednesday, forcing evacuations, destroying buildings, and diminishing air quality across the region.

The biggest is the SCU Lightning Complex Fire in the San Francisco Bay Area. The giant cluster of blazes began Tuesday morning and has since expanded to encompass at least 34,000 hectares across five counties: Alameda, Contra Costa, Santa Clara, San Joaquin, and Stanislaus. The fire, which is just 5% contained, has injured two people and prompted evacuation orders in parts of four of the five affected counties. (San Joaquin is the only one without such orders.)   

In Napa and Sonoma Counties, a cluster of six fires known as the LNU Lightning Complex Fire has burned more than 18,600 hectares, according to Cal Fire. That's an area larger than Washington, D.C. At least four people have been injured and 50 buildings destroyed. Another 1,900 additional structures are threatened. As of Wednesday morning, the complex fire was 0% contained. 

Meanwhile, in San Mateo and Santa Cruz counties, the CZU August Lightning Complex Fire has forced over 22,000 people to evacuate. The fire began in the Santa Cruz Mountains.  

Poor air quality throughout the region

Much of the Bay Area can feel the fires' impacts in the air. Most regions reported unhealthy air quality on Wednesday morning, and San Francisco residents saw soot and falling ash, according to SFGate. The area's Air Quality Management District issued "Spare the Air" alerts through Wednesday, which prohibit residents from burning wood.

Ashy skies have been reported as far away as Shasta Lake, more than 320 kilometres north of Napa and Sonoma counties.

Usually when air quality suffers, fire-safety experts recommend staying inside as much as possible and wearing N95 masks when outdoors, since those filter out smoke particles. But given the a nationwide shortage of N95s, many Californians lack effective masks.

Climate change is increasing the frequency and severity of wildfires

The fires erupted at the end of a major heat wave across the western US, which caused temperatures to top 38 degrees in parts of Northern California. 

Climate change increases the likelihood of extreme heat events: The 10 warmest years on record overall have all occurred since 1998, according to NOAA. After a heat wave in Europe killed 70,000 people in 2003, researchers calculated that climate change made such a heat wave four times more likely.

The hotter and drier land gets, the likelier fires are to occur. A recent analysis by Stanford University found that average temperatures during wildfire season in California have risen by more than 2 degrees Fahrenheit, while precipitation has dropped by 30%. Those conditions have more than doubled the state's total number of extreme wildfire risk days in autumn.  

Nine of the 10 biggest fires in California history have occurred since the year 2003.

But the trend isn't limited to one state. Large wildfires in the US overall now burn more than twice the area they did in 1970. In the western part of the country, the average wildfire season is 78 days longer than it was 50 years ago.

Rhea Mahbubani contributed reporting.

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