Los Angeles Times

McKinney fire has hit stratosphe­re

High heat, parched landscape turn deadly 55,000-acre blaze into own force of nature.

- By Corinne Purtill

A fire big enough to make its own lightning used to be as rare as it sounds.

But the McKinney fire, which erupted Friday, generated four thunder and lightning storms within its first 24 hours alone. A deadly combinatio­n of intense heat, parched vegetation and dry conditions has turned the 55,000-acre blaze in the Klamath National Forest into its own force of nature.

Four times, columns of smoke rose from the flames beyond the altitude at which a typical jet flies, penetratin­g the stratosphe­re and injecting a plume of soot and ash miles above the Earth’s surface. It’s a phenomenon known as a pyrocumulo­nim-bus cloud, a byproduct of fire that NASA once memorably described as “the fire-breathing dragon of clouds.”

In Siskiyou County, the

‘It just felt like the McKinney fire was like clockwork . ... It’s hot and dry. It’s right in the Klamath.’

— Kai Wilmot, a University of Utah researcher and co-author of a study on wildfire smoke plumes

water in these clouds returned to Earth as rain, accompanie­d by thunder, wind and lightning, in “a classic example of a wildfire producing its own weather,” said David Peterson, a meteorolog­ist at the U.S. Naval Research Laboratory, which has developed an algorithm to distinguis­h fire-induced thundersto­rms from traditiona­l ones.

Investigat­ors have yet to determine the cause of the McKinney fire, which grew rapidly in hilly, challengin­g terrain and was uncontaine­d as of Tuesday.

Mike Flannigan, a fire scientist at Thompson Rivers University in western Canada, said he isn’t shocked to see fires this powerful. The data have been pointing in this direction for years. He just didn’t think they’d be happening this soon.

“What we’re seeing in the western United States and in British Columbia in the last few years, I would not have expected to see until 2040,” Flannigan said. “The signal is clear: this is due to human-caused climate change. It can’t be any clearer than that. It’s happening more rapidly than I would have expected. This is my field, and this is surprising how rapidly things are changing.”

It isn’t just that wildfires are more powerful, more frequent and burning more acreage each year than ever before, he said. The energy generated by these conflagrat­ions is also creating columns of smoke so big that they leave the tropospher­e, the bottom layer of the atmosphere that wraps the Earth “like an apple skin,” as Flannigan put it.

The tropospher­e is where weather happens, and where eye-searing clouds of smoke and soot circulate even from moderately sized fires. But when a smoke column such as those emanating from the McKinney fire shoots through that layer and enters the stratosphe­re — the higher, more stable layer above — it creates havoc with local weather and seeds the Earth’s atmosphere with aerosol pollutants whose consequenc­e science is still sorting out.

Days before the McKinney fire broke out, researcher­s from the University of Utah published a new study in the journal Scientific Reports documentin­g the growth of smoke plumes in wildfires over most of the last two decades.

The research team looked at 4.6 million readings of smoke plumes recorded in the western U.S. and Canada between 2003 and 2020. The data were taken every hour from fires burning in August and September in each of those 18 years.

In four of the geographic­al regions they examined, maximum smoke plume height increased by an average of 320 feet per year. The most pronounced growth of all was in California’s Sierra Nevada, where maximum plume height ballooned by an average of 750 feet in each year of their study.

“If we have climate trends that are encouragin­g faster fire spread, more intense wildfire activity, greater heat flux off of these fires, we can expect a higher plume top height,” said Kai Wilmot, a University of Utah postdoctor­al researcher in atmospheri­c sciences and a coauthor of the study.

These smoke columns are not only taller, Wilmot and his colleagues noted, but with each passing year, they also grew more densely packed with microscopi­c bits of soot and ash. This fine particulat­e pollution, known as PM2.5, is linked to asthma, cardiovasc­ular problems and premature death.

And some of the nation’s most intense growth in smoke emissions is coming from the Klamath region. The data are unclear on how much the height of Klamath smoke is increasing, Wilmot said, but the concentrat­ion of harmful particulat­e pollution coming out of its clouds most definitely is climbing.

A paper that the team published last year looking at fire data from 2000 to 2018 highlighte­d the Klamath region as a hotspot of emissions, particular­ly in the month of August.

“It just felt like the McKinney fire was like clockwork,” Wilmot said. “We’re right on the cusp of August. It’s hot and dry. It’s right in the Klamath. And then overnight, boom.”

Plume height is a function of both atmospheri­c conditions, such as higher temperatur­es and decreased humidity, as well as fire size, which is largely determined by the amount of dry vegetation available to burn. The Klamath area has all those qualities in abundance.

California is in the middle of the worst drought since records began. Average summer temperatur­es in California are 3 degrees higher now than they were at the end of the 19th century.

The days before the fire were a sweaty mess of tripledigi­t temperatur­es and low humidity, which further dried plants already parched from a dry winter. The fire started in an overgrown area previously used for logging, which meant fewer fire-resistant old trees and a lot more smaller and easily flammable younger ones.

When plants burn, the carbon stored in their leaves is released into the atmosphere, adding to the concentrat­ion of greenhouse gases. But as the Utah team noted, fires spew tons of fine particulat­e pollution as well.

Measuring less than 2.5 microns across, these tiny particles of pollution can be inhaled deep into the lungs when breathed down here on the ground. In the stratosphe­re, they wreak a different kind of havoc that scientists don’t yet fully understand.

“The more we know about smoke, the more we know it’s bad for us,” Flannigan said.

Before massive, climatecha­nge induced wildfires, volcanoes were the primary vehicle that sent soot blasting into the stratosphe­re.

Scientists studying the aftermath of the massive 2019 and 2020 wildfires in Australia calculated that their emissions were on par with that of a mid-size volcanic eruption.

The Earth’s geologic record shows that over time, these particles can act as a cooling system, deflecting the sun’s radiation before it can enter the atmosphere. But it’s a complicate­d dance. Separate research from MIT on the Australian fires found that their smoke plumes depleted the ozone layer, which protects the Earth from ultraviole­t radiation.

The long-term consequenc­es aren’t clear. We simply don’t have millennia worth of data on the planetary effects of human-aggravated mega-fires, the way we do with volcanoes.

Social media is full of video clips of volcanic-like clouds roiling skyward from the Klamath National Forest. They’re going to become more common, as are fires powerful enough to generate their own lightning.

“The trend is to see more and more of these suckers,” Flannigan said. “It’s horrible, but we have to learn to live with it.”

 ?? WHEN A SMOKE Luis Sinco Los Angeles Times ?? column such as one from the McKinney fire enters the stratosphe­re, it creates havoc with local weather and seeds the Earth’s atmosphere with aerosol pollutants. Above, the blaze near Yreka, Calif.
WHEN A SMOKE Luis Sinco Los Angeles Times column such as one from the McKinney fire enters the stratosphe­re, it creates havoc with local weather and seeds the Earth’s atmosphere with aerosol pollutants. Above, the blaze near Yreka, Calif.

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