Climate change has had an impact on the California fire season since the beginning or mid-1980s, said UC Agriculture and Natural Resources (UC ANR) researcher Scott Stephens, during a interview on Capitol Public Radio with Ed Joyce. Stephens is a professor at UC Berkeley, a UC ANR Agricultural Experiment Station researcher and co-director of the UC Center for Fire Research and Outreach.
“The amount of snow left on the ground is decreasing because it is melting earlier,” Stephens said. "This creates a longer period of time when wildfires can ignite."
Also the density of trees in the state's forests has increased dramatically.
“We've gone from about 60 to 100 trees per acre to places we have today with 400 or 500 trees per acre, a massive change that has increased their vulnerability to fire, drought and insects,” Stephens said.
Stephens spoke about how the overly dense forest can be addressed by land managers.
"Thinning is sometimes controversial," he said. "It's very easy to think that you're going to remove some trees to reduce the community of crowns, but if you're going to do a restoration treatment with fire in mind, you have to deal with the surface fuels. Also, just the culmination of mortality for decades and decades is already on the ground of the forest."
Joyce noted the astonishing number of dead trees in the Southern Sierra, which the U.S. Forest Service recently pegged at 66 million.
"That's a great example of a manifestation of an unsustainable forest condition," Stephens said. "I was just down in the Southern Sierra about five days ago and I saw those landscapes of thousands of dead trees, many of them large, especially in the ecozone where we go from shrubs to forests. Those areas have been very dry."
Stephens continued: "We really are in this warming climate with more variability. So, it's on us. . . . We can't just keep kicking the can down the road. We're running out of time."