“It’s not just how hot are the heat waves; it’s how hot is it the rest of the time,” Swain said. “What really matters is the sustained warming and drying over seasons and years.”
Some of California’s current fires are in areas that don’t regularly burn
It’s important to remember that fires are a normal part of the ecology in California, from the coniferous forests in the Sierra Nevada to the chaparral shrubland in the south. Periodic blazes clear out decaying vegetation, restore nutrients to the soil, and help plants germinate.
Humans, however, continue to make California’s wildfires worse at every step. By suppressing naturally occurring fires, fuel has accumulated in forests and shrublands, increasing the danger when fires do ignite. People are also building closer to areas that are prone to burn. That increases the likelihood of starting fires and raises the blazes’ damage toll. People have also introduced invasive plant species like eucalyptus trees, which have spread throughout California and readily ignite. And burning fossil fuels emits greenhouse gases that are warming the planet, increasing the amount of vegetation that can burn.
Even with this backdrop, some of the fires in California stand out because they are raging in places that don’t burn very often.
“I think what’s key to understand is that different parts of California have very different normal fire seasons,” said Crystal Kolden, an assistant professor of fire science at the University of California Merced. “And that’s in part because California is such a big state. It has really variable topography and different vegetation or ecosystems across the state.”
Because the coastal forests are under the influence of marine weather systems, they are much cooler and retain more moisture than the pine forests of the Sierra Nevada and other inland areas. The coastal forests do burn periodically and are home to many species that have adapted to fire, but they rarely ignite during the summer.
That some portions of them have burned is remarkable, a product of high atmospheric pressure over the area that allowed heat to accumulate and overwhelm the cooling effect from the ocean. “Those coastal areas are incredibly dry, incredibly hot relative to normal, and that arid and hot condition had this potential to have really explosive fires,” Kolden said.
Covid-19 is adding a wallop to California’s fires
The Covid-19 pandemic has rattled every part of society, and firefighting efforts are not immune. “It definitely has affected our response, primarily in our inmate fire crews,” Bennett said.
California often relies on prison labor to bolster its firefighting efforts, with almost 200 inmate fire crews. Inmates are paid between $2 and $5 a day, plus $1 per hour when fighting a fire. But with severe Covid-19 prison outbreaks in the state, some inmates were released to relieve overcrowding. Others were hampered by infections, and many remain under quarantine. The number of available inmate fire crews has been nearly halved.
