"Climate whiplash" helps fuel extreme Western wildfires

• Human-caused climate change, population growth and land management practices are combining to create dangerous and damaging blazes.

The big picture: California had a wet winter and banner snow season for the second year in a row. But that was followed by a record hot and also quite dry summer.

• This swing from cool and wet to hot and dry set California up for destructive wildfires once fire weather conditions turned extreme, UCLA climate scientist Daniel Swain told Axios.
• "There was tremendous growth of grass and brush as a result of these damp and favorable conditions over the past two years, and there was also little large fire activity to perform 'de facto brush clearing' during that period," Swain said.

State of play: The summer was the state's hottest on record since such records began in 1895, NOAA found Tuesday. However, coastal areas of Southern California didn't see extreme heat until the past two weeks.

• The long-lasting and intense heat wave — which brought downtown LA to within 1°F of tying its all-time high temperature of 113°F and broke numerous other records across the region — has led to extremely dry conditions as the atmosphere swiftly stole moisture from vegetation.

The intrigue: Swain likened the heat's effect on Southern California's landscape to that of a "kiln" used to bake and dry clay.

• Mike Flannigan, a wildfire expert at Thompson Rivers University, said "The ability to suck moisture out of the dead fuels increases almost exponentially" in such hot and dry conditions.
• Extreme fire weather conditions, which are becoming more common and severe with climate change, he told Axios, led to fierce fires that can't be put out directly.
• The past few days, for example, have featured wildfires that have run up and over mountains; backed down hills and into communities; and manufactured their own weather, complete with towering clouds of smoke and ash that produced thousands of lightning strikes.
• "The public largely believes we can extinguish all the fires all the time, and this is not true," Flannigan told Axios.

Between the lines: Wildfire ignition sources can range from arson to someone turning on a motor that produces a spark. Such sources are abundant near populated areas, says Neil Lareau, a meteorologist who specializes in wildfires at the University of Nevada at Reno.

• What sets conflagrations like this week's apart from small fires that die out quickly are the fire weather conditions, which are in turn influenced by climate.
• "The sources vary, but the fire weather conditions then play a huge role in whether those ignitions can be contained quickly, or spread out of control," he told Axios.

Atmospheric instability, which has led to wildfires dominated by towering plumes of smoke rising to 35,000 feet at times, has also helped to increase fire severity, said John Abatzoglou, an atmospheric scientist at U.C. Merced.

Zoom in: A warming climate is likely to bring more of these sudden shifts between cool and wet and extremely hot and dry periods, which Swain refers to as "hydroclimate whiplash."

• Studies he has participated in and from other researchers have projected this outcome due to human-caused warming.
• At the same time, increasing development and land management practices are also playing a role in these wildfires. Many blazes in California and Nevada have started within or spread into areas where homes and businesses border fire-prone landscapes.
• Such zones are known as the wildland urban interface.

The bottom line: Weather whiplash can exact a disastrous toll and looks to play an increasing role in Southern California's climate in the future.