A Climate Reckoning in Fire-Stricken California

Climate scientists say the mechanism driving the wildfire crisis is straightforward: Human behavior, chiefly the burning of fossil fuels like coal and oil, has released greenhouse gases that increase temperatures, desiccating forests and priming them to burn.

Mark Harvey, who was senior director for resilience at the National Security Council until January, said the government had struggled to prepare for situations like what was happening in California.

“The government does a very, very bad job looking at cascading scenarios,” Mr. Harvey said. “Most of our systems are built to handle one problem at a time.”

In some ways, this year’s wildfires in California have been decades in the making. A prolonged drought that ended in 2017 was a major reason for the death of 163 million trees in California forests over the past decade, according to the U.S. Forest Service. One of the fastest-moving fires this year ravaged the forests that had the highest concentration of dead trees, south of Yosemite National Park.

Further north, the Bear Fire became the 10th largest in modern California history — burning through an astonishing 230,000 acres in one 24-hour period.

“It’s really shocking to see the number of fast-moving, extremely large and destructive fires simultaneously burning,” said Daniel Swain, a climate scientist in the Institute of the Environment and Sustainability at the University of California, Los Angeles. “I’ve spoken to maybe two dozen fire and climate experts over the last 48 hours and pretty much everyone is at a loss of words. There’s certainly been nothing in living memory on this scale.”