Why are California's wildfires so intense and what can be done?

High temperatures and lack of rainfall, exacerbated by years of drought, are contributing factors – and climate change

The National Weather Service has issued a red flag warning in parts of California warning of conditions conducive to the growth of wildfires, including strong winds, low humidity and very high temperatures.

The White House has declared California’s fires a major disaster and there are signs they are growing more intense.

Where are the fires?

More than 4,500 firefighters have been fighting the so-called Carr fire 160 miles north of Sacramento since late July. On Saturday, the blaze killed a power company lineman, the seventh person to die in the fire.

The cause of the blaze is under investigation, though the LA Times reported that it may have come from a vehicle towing a trailer with a flat tire, its metal rim creating sparks as it rolled along.

The Mendocino Complex fire, now the sixth-largest in recorded state history, is a pair of massive fires burning on either side of Clear Lake, about 100 miles north of San Francisco. On Saturday night, fire expanded dramatically to cover nearly 230,000 acres. The conflagration, which has forced thousands from their homes and burned dozens of structures, is now the most pressing of the 17-large wildfire emergency across the state.

Why are they so intense?

In short, high temperatures and lack of rainfall, exacerbated by years of drought. Record precipitation last winter resulted in a boom in the growth of grasses, shrubs, trees – what fire fighters call fuel – across the state.

California has grown hotter in recent years, this summer record temperatures have been recorded across the state. The day the Carr fire spread out of control was 26 July, the same day thermometers in nearby Redding hit 45C (113F).

The heat has periodically overwhelmed electrical systems, leaving parts of Los Angeles without power. Palm Springs had its warmest July on record, with an average of 36.3C (97.4F), while Death Valley averaged 42.3C (108.1F), also a record. It was the warmest July on record in San Luis Obispo, Oxnard, Camarillo, Long Beach, Van Nuys, Lancaster and Palmdale.

But record heat maybe not be the most useful measure. Overnight and summertime minimum give insight in how sustained the heat has become. The top six warmest summertime minimum temperatures in California have occurred in the last six years, readings that show California not cooling off at night as it once did.

“You have greenhouse gases acting like a blanket and not letting things cool down as much – keeping things warmer,” Nina Oakley, regional climatologist for the Western Regional Climate center in Reno, told the Los Angeles paper.

Is it climate change?

The last five years have been among the hottest in 124 years of record keeping, leaving little room for other interpretations.

“In the past, it would just be kind of once in a while – the odd year where you’d be really warm,” state climatologist Michael Anderson told the LA Times. “That’s definitely an indication that the world is warming, and things are starting to change,” said Anderson. “We’re starting to see things where it’s different. It’s setting the narrative of climate change.”

What can be done?

Bluntly, stop using fossil fuels. “People are doing everything they can, but nature is very powerful and we’re not on the side of nature,” California Governor Jerry Brown said last week. “We’re fighting nature with the amount of material we’re putting in the environment, and that material traps heat.”

Will it improve?

Not necessarily. The sudden transitions back and forth from wet years to dry years, what scientists call “climate whiplash – are contributing to the increased risk of wildfires across the state. In California, peak wildfire season is in the fall, and there’s no sign of an onset of unseasonal rainfall.

“We’re having peak fire season conditions in the off-peak time of year, and there’s no real indication that things are going to get better before the peak of the season in the fall,” says Daniel Swain, a University of California, Los Angeles climate scientist and leading expert on climate whiplash.