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Several studies say climate change behind the wild fires ravaging California

Climate change is making forest fires in California more intense and is prolonging the fire season, with twice as many days of fire weather today compared to the early 1970s

As highly destructive wind-driven wildfires continue to tear through Los Angeles, several studies point at climate change as the force fuelling these fires. The January 2025 fires are being driven by strong winds. While the winds are not unusual at this time of year, the delayed onset of the rains means that it is unusually dry. 

Climate change is making it less likely to rain in late fall and early winter when the hot, dry, Santa Ana winds peak. Much of Southern California had almost no rainfall since July 2024., despite being halfway into the normal rainy season – the second-driest period in 150 years. 

California had its hottest June and July and the second hottest October, with many of the hot days scientifically linked to climate change. 2024 was the hottest year on record globally, due to climate change. This heat and lack of rainfall left the vegetation tinder dry when the Santa Ana winds started. Climate change is thus increasing the probability of the strong winds and dry conditions overlapping, which together can intensify fires. 

Many of the scorching days in California were scientifically attributed to climate change, and the state saw its hottest June and July as well as its second-hottest October. Because of climate change, 2024 was the warmest year on record worldwide. When the Santa Ana winds began, the vegetation was dry due to the heat and lack of rainfall. Thus, climate change is making it more likely that dry weather and strong winds will coincide, which can exacerbate flames.

There are up to 30 fewer days in a year when it is safe to set preemptive controlled burns in sections of southern California due to climate change, which makes it more difficult to prevent fires.

Intensifying fire season

In some areas of California, the arrival of autumn and winter rains is being postponed more and more due to climate change. This is drying out the vegetation in conjunction with rising temperatures, increasing the area’s susceptibility to fire and resulting in an annual increase in the area burned. Climate change is largely to blame for the fivefold rise in the annual area burned by wildfires in California compared to the 1970s.

The use of fossil fuels has increased the number of days that big fires can occur. Additionally, flames in California are spreading more swiftly due to climate change; roughly 25% more fires now move extremely quickly.  

The lengthening of the fire season is another effect of climate change. In California, the number of autumn days with extreme fire weather has more than doubled since the early 1980s, and there are twice as many days with fire conditions now as there were in the early 1970s. Over the past 40 years, the number of “critical danger days” caused by megafires in southern California has tripled. Over the past few decades, California’s fire weather has increased by 66–90% due to climate change-induced drought and warmth. 

Similar trend in previous years

Scientific studies have found that climate change worsened previous fires in California and the Western US. While assessing the Western North America wildfire risk in 2015-16, extreme vapor pressure deficits (VPD) have been associated with enhanced wildfire risk. Using one model, it was found for 2015/16 that human influences quintupled the risk of extreme VPD for western North America. In the assessment of western US fire weather risk during 1979-2020, it was estimated that human-caused climate change contributed to an additional 4.2 million ha of forest fire area during 1984–2015, nearly doubling the forest fire area expected in its absence.

During the Northern California wildfires in 2014, the fire season in the region was the second largest in terms of burned areas since 1996. Studies attributed this increase in fire risk in California to human-induced climate change. And during the California wildfires, between 1972-2018, California experienced a fivefold increase in annual burned area, mainly due to more than an eightfold increase in summer forest‐fire extent. Increased summer forest‐fire area very likely occurred due to increased atmospheric aridity caused by warming, a study had found.

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