When the Washburn Fire burned through part of Yosemite’s iconic Mariposa Grove in July, photos of its famed giant sequoias steeped in smoke and surrounded by automated sprinklers to shelter them from the flames shocked viewers around the globe.

Less than a year earlier, similar photos showed the trunk of the sequoia known as General Sherman, the world’s largest tree, wrapped in a tinfoil-like material to repel the flames of the KNP Complex Fire. Yet, while those efforts helped save the celebrity trees from the infernos, the annihilation elsewhere in California’s Sierra Nevada mountains is difficult to grasp: The U.S. Forest Service estimates that, in 2020 and 2021 alone, wildfires killed 13 percent to 19 percent of the world’s giant sequoias.

“Those are crisis numbers,” said Tim Borden, the sequoia restoration and stewardship manager at Save the Redwoods League, an advocacy nonprofit stewarding several sequoia groves that have been deeply impacted by high-severity fires. “The lights are flashing red.”

While climate is one driver of the growing size and intensity of the megafires decimating the world’s largest trees, it’s only part of the picture.

“Part of this is caused by how our forests have changed because of management decisions that were well intentioned at the time, but not really fully known,” Borden said.