California wildfires: What's behind the rising frequency and intensity?

California wildfires surge due to rising temperatures, drought, and climate change impacts.

A wildfire, driven by strong winds, erupted just northwest of Los Angeles on Tuesday, prompting evacuations in California's Malibu as the blaze threatened homes, and knocked out power.

The blaze, known as the Franklin Fire, expanded rapidly overnight, growing from 5 acres to 2,713 acres as it spread across steep mountainous terrain.

It moved southward over the Pacific Coast Highway in the city, which has a population of around 10,000 residents.

The fire, which remains unbridled, has destroyed a small number of homes, but no injuries or fatalities have been reported, according to Los Angeles County Fire Chief Anthony Marrone.

Governor Gavin Newsom confirmed that California had secured a grant from the Federal Emergency Management Agency (FEMA) to aid in firefighting efforts.

Authorities conducted door-to-door evacuations overnight, warning thousands of residents as the fire spread.
 

 

 

 

 

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The National Weather Service (NWS) issued a red flag warning, indicating heightened fire risks as Santa Ana wind gusts could rreach up to 104 km/h (65 miles per hour), further escalating the fire danger in the area.

 

 

 

 

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The increasing frequency and intensity of such wildfires have been linked to climate change, with NASA’s reports showing a rise in extreme weather conditions and changing fire patterns in the region over the past few decades.

California has seen a surge in the size and frequency of wildfires in recent years. According to Cal Fire, eight of the state's ten largest fires and twelve of the top twenty have occurred in the past five years, burning around 4% of the state's land area, equivalent to Connecticut.

The Dixie Fire (2021) and August Complex Fire (2020) were particularly large, each consuming nearly 1 million acres. These and other wildfires have caused significant destruction, with California's thirteen most destructive fires in the last five years destroying about 40,000 homes and businesses.

The total area burned by wildfires in California and the average size of these fires have been increasing, according to Keith Weber, a remote sensing ecologist at Idaho State University and principal investigator for NASA's Historic Fires Database. The data reveals that between 1970 and 1980, about 3% of the state's land burned, while from 2010 to 2020, that figure rose to 11%. This trend toward larger fires is evident in decadal maps from the National Interagency Fire Center.

 

NASA

Jon Keeley, a scientist with the U.S. Geological Survey, points to a combination of factors contributing to this surge, including climate change-induced drought and heat, overgrown forests from decades of fire suppression, and growing populations near forested areas.

The impact of these fires is devastating, both on the ground and in satellite imagery. For example, the image from NASA’s Landsat 8 shows the burn scar left by the Dixie Fire, which destroyed 1,329 structures and cost millions to suppress. The photograph of Plumas National Forest further illustrates the extensive damage caused by the fire.

The 2020-2021 drought was especially severe. John Abatzoglou, a climate scientist at the University of California, Merced, explains that dry winters combined with extreme summer heat and atmospheric aridity created conditions where soil and vegetation were left parched, making the landscape more susceptible to wildfires that are harder to suppress.

Data from the Western Regional Climate Center shows that the northern two-thirds of California received just half of the usual rainfall in recent years. The U.S. Drought Monitor categorized 85 to 90 percent of the state as experiencing “exceptional” or “extreme” drought in summer 2021. The period from September 2019 to August 2021 marked the second-driest on record for California, according to the National Centers for Environmental Information.

NASA

Daniel Swain, a climatologist at the University of California, Los Angeles, highlighted that climate change is intensifying California's wildfires by raising temperatures. "Heat essentially turns the atmosphere into a giant sponge, drawing moisture from plants and enabling fires to burn hotter and longer," he explained.

Meteorological data shows that from September 2019 to August 2021, California experienced its third-warmest period on record, with temperatures averaging 2.9°F (1.6°C) above normal. For every degree Celsius increase, air can absorb about 7 percent more moisture.

Abatzoglou pointed to a series of fires ignited by dry lightning in Northern California in August 2020. While he acknowledged the rarity of such events, he stressed that climate change is exacerbating the warming and drying of fuels, which makes the land more prone to large fires. "I am less convinced of bad luck," he said, emphasizing that climate change is playing a direct role in the fire's intensity and frequency.