California is facing a record fire year. Three massive wildfires — the Woolsey and Hill Fires in Southern California and the Camp Fire in Northern California — have destroyed 225,845 acres in the past six days.
The Camp Fire is now the most deadly forest fire in state history, with 42 confirmed fatalities and over 200 missing. The land burned by these three fires alone is now equal to all the land burned in an average year.
But why in 2018? Are we just having an unlucky year, or are there additional factors at play? In a tweet early Monday morning, President Donald Trump blamed the fires on poor forest management. According to USC scientists, however, Trump's statement was a far cry from the truth.
"Fire is a natural part of any forest ecosystem, and brush must be periodically cleared or burnt away for the forest to remain healthy," said Victoria Petryshyn, a Lecturer in the USC Environmental Studies Program. However, according to Petryshyn, the Woolsey Fire is occurring in an urban area, not a forest ecosystem.
"It had nothing to do with federal forest management practices," Petryshyn said.
Petryshyn added that, with only three percent of California's forests managed by the state itself, a large portion of the problem falls on the shoulders of Trump himself, who has proposed massive cuts to maintenance of federal lands.
"It's difficult to understand why [Trump] said [that statement] because it runs contrary to everything we [scientists] understand," said Julien Emile-Geay, a USC Associate Professor of Climate Dynamics in Earth Sciences. "This tweet came out of complete ignorance."
The science explaining California's increased fires is slightly more complicated than poor forest management.
One cause is the Santa Ana winds, powerful gusts that dry out vegetation and increase fire mobility. According to Petryshyn, the Santa Ana winds are caused by California and Nevada geography. Air masses from the Great Basin and Mojave Desert travel west over the Sierra Nevadas, losing their moisture. This air is then funneled through mountain passes like the San Gregorio Pass, resulting in hot, dry winds moving at rapid speeds toward coastal areas like Los Angeles.
The Santa Anas also peak in autumn months, when California could be recovering from the summer heat. Conditions are actually exacerbated: vegetation becomes even drier, and the rapid winds can move sparks, helping fires grow and spread.
California's recent drought has also led to the spread of fire by drying out vegetation. According to Petryshyn, this effect was aided by an unusually high rainy season in 2016.
"We were hit by many atmospheric rivers [in 2016], which were good because they provided drought relief, but they also caused a lot of new plant growth that couldn't be sustained in our normal dry climate," Petryshyn said. "As all that brush dried out, it created a nice tinder box."
On top of natural factors, human activities are responsible for intensifying forest fires.
For one, humans are successful firefighters. As they have expanded settlements farther into the wilderness of California, they have increasingly come into contact with naturally-occurring forest fires. Paradoxically, though, when firefighters extinguish a fire, they leave leftover fuel. Decades upon decades of human firefighting has allowed California forests to accumulate dead wood, building potential for larger, more destructive fires.
According to a study published in 2016, human-caused climate change is now a major driver in wildfires in the western United States, which have been steadily rising for the past two decades. But in recent years, the last four of which are the four hottest on record, the problem has gotten even worse.
"Climate change is giving us higher overall [temperatures], less cool nights, and more dry days," Petryshyn said. "So it generally makes any fire more extreme, faster moving, and more dangerous.
"Climate change is a very abstract issue for a lot of people," Emile-Geay said. "Perhaps these wildfires make it more concrete…Climate change is not the only driver, but it is an important one, and that's exactly the type of things we expect to see more of, unfortunately, as climate change proceeds."