Bigger, earlier, more
A year ago, researchers at UC Irvine issued a report on Southern California wildfire trends that concluded what any nonscientist, longtime resident already knew — there have been a lot more wildfires in the region during this century.
But the report, from UCI's Department of Civil & Environmental Engineering, wasn't anecdotal. It was based on data from thousands of California fires over the previous 100 years. Researchers looked at fire events in two distinct camps, those that happened from 1920 through 1999 and those that happened from 2000 through 2020.
The data was clear: Fires are steadily becoming more frequent and more destructive.
“Each new year of the 21st century has been a record-breaker in terms of wildfire damage in California,” said report co-author Tirtha Banerjee, a professor of civil & environmental engineering at UCI.
The report also looked at some details. Researchers noted that while big fires (500 acres or more) are less frequent, they generate the most death and destruction — accounting for about 20% of all events and 97% of the acres burned.
“When fires get large, their deadliness increases,” Banerjee said.
What's more, this century also has seen the emergence of two seemingly disparate trends, the rise of so-called “extreme” fires — 10,000 acres or more — and the number of small, human-caused fires in remote locations.
And as the fire season has extended, and fire risks have grown, the areas touched by fires have expanded.
From 1920 to 1999, the one part of Southern California that was rated by fire officials to experience “very high wildfire density” was Los Angeles County. But in this century, the areas taking on that official label have expanded throughout the region to include Ventura County and portions of Riverside, San Diego and San Bernardino counties, according to the UCI report.
This century also has seen the emergence of the coast as a fire zone. Though big fires hit the Malibu Canyon area, and other coastal spots, last century, such events typically were rare. In the 2000s, the UCI report found, virtually every coastal county in California has seen higher risk, with the bulk of coastal fires happening between Monterrey and San Luis Obispo counties.
The UCI report also backed up the idea that the fire season is what the Coastal fire suggests it is — year-round and more intense.
Without looking at any report, and relying on what he'd seen his crews handle in recent years, Orange County Fire Authority Chief Fennessy stood near the burned homes of Laguna Niguel and said:
“Unfortunately, this is what we're going to be experiencing over the next several months and the next several years.”