Article Title: California Swings from Floods to Fires: A Climate Whiplash Story
weniger als ein Jahr CNN — Back-to-back atmospheric rivers dumped record rainfall on Southern California from December to February, flooding roads, floating cars, and triggering hundreds of mudslides. It was a deadly winter of storms that left the region gasping for breath. But the pendulum of weather extremes has swung again.
The drought has now taken hold, following one of the region’s hottest summers and the driest winter on record. The lush vegetation that thrived under last year’s torrential rains has been reduced to tinder, fueling a week of unprecedented wildfires that have ravaged Los Angeles neighborhoods, driven by an once-in-a-decade Santa Ana wind storm.
"Had we seen significant or widespread precipitation in the weeks and months leading up to this event, we wouldn’t be seeing the magnitude of the devastation we’re seeing now," said Daniel Swain, a climate scientist at the University of California, Los Angeles.
California is particularly vulnerable to the worst impacts of human-driven climate change. Its Mediterranean climate is already prone to extremes; most rain falls in the winter, and summers are dry. Small changes in weather patterns can send the state into tailspins of biblical floods or devastating droughts.
A study published Thursday in the academic journal Nature warns that these abrupt swings between dry and wet conditions, known as "weather whiplash," are becoming more frequent as the planet warms due to fossil fuel pollution. They exacerbate the risk and severity of wildfires and sudden flooding.
The series of winter storms last year triggered a boom in vegetation growth, with Swain estimating it was double the normal amount for the region. That fuel, combined with the persistent drought and intense heat, set the stage for this week’s catastrophic fires.
A deep bone-dry climate and abundant fuel are enough to ignite wildfires. But the fires this week were supercharged by an unusually potent Santa Ana wind storm, an added destructive factor to an already dangerous recipe. Gusts up to 160 km/h fanned the flames from house to house, making it nearly impossible for firefighters to control the rapid spread.
As California waits for winter rains, its vulnerability to extreme fire behavior will increase. Historically, the fire season in California peaked in October, when summer-dry vegetation collided with Santa Ana winds before winter rains arrived. But the Los Angeles fire storm is the latest example that there’s no fire season anymore in a warming world.
"Traditionally, this time of year is not peak fire season, but we’re disproving any notion of that. It’s year-round in the state of California," California Governor Gavin Newsom said on Tuesday.
It has been the driest start to winter on record in Southern California, according to Swain, and the National Interagency Fire Center warns of significant potential for wildfires above normal until January. It could also mean an earlier start to the traditional fire season in higher elevations, the agency cautioned.
Until California receives a significant winter rain, the threat of violent fires will persist. The changing climate makes it even harder to predict when that might happen.
– Rachel Ramirez, Laura Paddison, and Ella Nilsen contributed to this report.
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