Last year’s California fire season was affected by power shutoffs, climate change and better preparation.
Here’s what we’ve learned from it:
The 2019 California fire season was much less destructive and deadly than those of the two previous years.
2017 and 2018 were California’s deadliest and most destructive fire seasons in the state’s long recorded history of wildfires. But 2019 was different, despite the fact that the Santa Ana winds were the strongest in a decade.
Fire officials attribute the difference to a combination of preparation and luck.
Last year, fire departments ordered evacuations more quickly, and they placed more fire crews and aircraft on standby. That’s the preparation component.
According to the Los Angeles County Fire Department, some of the 2019 wildfires burned in areas that had already been scorched in recent years. This left them without a lot of new fuel to burn (specifically, chaparral and shrubs). That’s where luck entered in.
The 2019 fire season saw California’s three big power companies — Pacific Gas and Electric, Southern California Edison and San Diego Gas & Electric — engaging in Public Safety Power Shutoffs (PSPS) in an effort to prevent wildfires caused by their equipment.
The largest blackouts were carried out by PG&E, as winds gusting more than 100 miles per hour blew through Northern California. In late October, the utility deliberately cut power to a record-breaking three million people. It was the second massive power shutoff in two weeks. The move angered the governor and left residents groping in the dark for almost a week.
It was also largely ineffective, as PG&E’s equipment is suspected of causing at least five wildfires, including the state’s largest fire of the year, the Kincade fire.
“We are coming off what was a historic event,” said PG&E spokesman Andrew Vesey after one of blackouts. “The reason we do this, as we’ve said many times, is for public safety. We continue to believe it’s the right thing to do.”
San Diego Gas & Electric, the first utility to implement blackouts as a fire prevention strategy, took a more surgical approach by turning off power to a small fraction of their customers at a time. Likewise, Southern California Edison limited its intentional shutdowns. Nevertheless, its equipment also is suspected of igniting at least two Southern California wildfires. The larger of these, the Woolsey Fire, charred almost 100,000 acres, destroyed more than 1,600 structures and killed three people.
Part of the problem may be the sheer numbers, which suggest that utility-caused wildfires are becoming more common. Cal Fire data indicates that fires ignited by power lines spiked from a five-year average of 296 to 408 in 2017 — the highest increase in any category of fire causes.
California is about 3 degrees warmer today than it was a century ago. Compare this to a global average of 1 degree warmer.
A warming atmosphere means potential wildfire fuels are drying out more quickly than they did a century ago, despite the fact that California is no longer in a drought. This means the state’s trees, shrubs and grasslands are primed to burn. Not only do drier plants ignite more easily, but the resulting fires grow bigger and spread faster.
And that effect increases exponentially with every degree of warming, according to climate scientist Daniel Swain, of the University of California, Los Angeles. So today’s hotter, climate-changed air is much more effective at drying vegetation to a crackle than it was 100 years ago.
For instance, California’s summertime wildfires burn eight times the acreage today than they did in the 1970s. Overall, the state’s official fire season has lengthened by 75 days over the past decades, according to CalFire.
Part of this is due to reduced snow accumulation in mountainous areas. And snow that does fall is melting away earlier. So spring arrives earlier, extending the dry season, and increasing the risk of wildfire.
The dry season often extends deep into the autumn, as seasonal rains become more unpredictable. In recent years, those rains haven’t kicked in until November, or even December. Climate scientists agree that this drier landscape, coupled with the notorious Santa Ana winds, is a recipe for disaster.
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