Scientists have known last year’s Castle Fire was probably the most destructive for California’s famously fire-resilient sequoias in at least 700 years, but a draft National Park Service report obtained by the Visalia Times-Delta puts a quantitative measurement on that fire’s climate-fueled toll. Between 7,500 and 10,000 monarch sequoias — about 10% to 14% of the world’s mature sequoia population — perished in the fire. “I cannot overemphasize how mind-blowing this is for all of us. These trees have lived for thousands of years. They’ve survived dozens of wildfires already,” Christy Brigham, chief of Resources Management and Science at Sequoia and Kings Canyon national parks, told the Times-Delta. Redwood forests are some of the world’s most efficient when it comes to removing carbon from the atmosphere, and also provide critical wildlife habitat and watershed protection for farmers and communities in the San Joaquin Valley.
“The precise threshold of climate change (rising temperatures, increasing drought magnitude, etc.) that may cause large and frequent high severity fires burning over entire groves, and the inability of trees to recover, are not known for coast redwoods or giant sequoias,” Thomas Swetnam, an emeritus tree ring researcher at the University of Arizona, told Earther at the time of the Castle Fire last year. “The fact that we are seeing some mortality of 1,000-plus year old trees now in some groves is a warning though that we may be approaching these thresholds.”
‘Like a ton of bricks’
The loss numbers, derived from satellite data, will be confirmed visually when scientists are able to hike the high-elevation groves still covered in snow. “I have a vain hope that once we get out on the ground the situation won’t be as bad,” Brigham told the Times-Delta. “but that’s hope — that’s not science.”
“Not much in my life in the natural world has made me cry, but this did,” Nate Stephenson, a research ecologist for the U.S. Geological Survey who works in the park and has been studying sequoias for years, told the San Francisco Chronicle. “It hit me like a ton of bricks.” (Visalia Times-Delta, San Francisco Chronicle, Earther, AP, The Guardian; Climate Signals background: Wildfires, 2020 Western Wildfire Season)