Christmas wildfires: How climate change puts California at risk all year round

What was once a condensed fire season has expanded as weather patterns change

Most Californians are unaccustomed to white Christmases. But shifting weather patterns have dusted the state with flurries rarely seen this time of year.

“It looked like my front yard had snow on it,” said 67-year-old Ron Tito, standing beneath the scorched hills encircling his oceanside town of Carpinteria.

It wasn’t snow but a coating of ash: a byproduct of the infernos that had engulfed hundreds of thousands of acres near Los Angeles – and a potential harbinger of devastation to come.

“We’re about ready to have firefighting at Christmas,” Governor Jerry Brown said after surveying the damage. “This is very odd and unusual.”

California’s history, seen from one angle, is a chronicle of natural disasters. The threat of floods, droughts and earthquakes hovers ever-present, and wildfires are a fact of life.

But this year they have been especially destructive. In October, a series of blazes raged across the rolling hills of California wine country and into populated areas, killing more than 40 people, incinerating thousands of structures and likely breaking a record for fire insurance claims.

In December, a time when cooler weather and rains usually mitigate the risk, hundreds of thousands of southern Californians have been pushed from their homes by powerful conflagrations – one of which, the Thomas Fire that had rained ash on Mr Tito’s yard, was still burning weeks after it ignited.

It is not just a matter of scale but of timing. The state typically had a fire season, with the odds of blazes climbing in the hot, dry summer months when fuel is abundant and the conditions are auspicious for fires to spread. Firefighters and residents could prepare accordingly.

That predictable window, experts say, has been thrown open. Fire season is starting to look more like a year-round threat. Christmas, as the governor said, may bring no reprieve.

“We don’t even consider fire season a season anymore. It’s not spring, it’s not summer, it’s not winter – the southern part of the state is year-round in terms of wildland fires, and the northland isn’t far behind,” said Scott McLean, a spokesman for Cal Fire.

While researchers caution against attributing any one fire to climate change, there is a broad consensus that warmer, drier weather is contributing to an overall increase in the frequency and severity of burns.

“There used to be a much more defined fire season in California in the sense that you could reliably say, ‘we need to start staffing up by this date and we can start demobilising some of the resources by this date,’” said J Keith Gilless, chair of California’s Board of Forestry and Fire Protection.

“When our rains start, in a typical year there was an average time they’d start in the fall and you’d have enough water and snow that the fire season was effectively over in much of the state. That just isn’t the case anymore.”

Climate change is supplying the basic ingredients. Temperatures in California have risen over the last half-century, including in the winter. Precipitation has become more variable, evidenced by the fact that the state is still recovering from a crippling drought that left it encrusted in combustible dry brush – the type of “extreme event” that is the hallmark of climate change, according to National Weather Service fire meteorologist Robyn Heffernan.

“Our fire seasons are starting early, they’re lasting longer and yes, we do believe that overall that is tied to changes in the climate,” Ms Heffernan said. “When we do get fires they tend to be much more active because of the underlying climate conditions”.

With those conditions in place, when high winds lash the landscape – as they have in both sets of destructive fires this year – flames are able to sprawl rapidly and outpace firefighters.

The trend is not a new one. According to research conducted by Leroy Westerling, a climate and fire scientist at the University of California, Merced, the duration of fires in the western US has increased more than eight-fold, and the number of days with fires burning soared from from 138 a year to 222 annually between 1973 and 2012.

In other words, there are flames more often than not.

“If you look around the western US in the last 40 years, we see steady increases in the number of fires not just in forest but in grassland, too,” Mr Westerling said. “We see bigger burns, larger and larger maximum fire sizes, more severe fires, longer fire season, longer-burning fires.”

But a recent spate of fires have underscored the new reality in California. Three of the 10 most destructive blazes in the state’s history occurred this year; 11 of the 20 worst have occurred since 2007.

“In the last few decades we’re certainly seeing warming in the West and a lot of times this is associated with drought or dry conditions. So that combination makes the vegetation much more susceptible to burning,” said Tim Brown, director of the Western Regional Climate Centre at the Desert Research Institute. “We are certainly in the last couple of decades seeing an increase in larger fires and an increase in more destructive fires.”

Scientists caution that hotter, drier weather is not the only factor driving more hazardous and frequent fires. Decades of focus on fire suppression have prevented the types of natural burns that clear out underbrush, leaving more fuel when large fires do start.

And more people have pushed into wildlands with higher fire risk, with some 11.2 million Californians spread across around 4.5 million homes in more remote, fire-susceptible areas as of 2010.

“Climate’s one piece of the puzzle, the fact that we have so much fuel in the landscape is part of the puzzle, the fact that so much of our populations wants to live in these beautiful rural areas is part of the puzzle,” Ms Heffernan said.

Setting aside the complex causes, the end result has become increasingly clear to Californians.

“It isn’t precisely clear what climate change is doing at this moment, what is the precise contribution of the warming climate and what is the natural variability,” Mr Brown, the California governor, told a climate conference as much of his state was ablaze.

“But we know that the fires you’ve seen on television and which people experience in California now, as we speak, are what we can expect and expect a lot more of.”