Lightning-sparked wildfires are scorching the Central Coast. This is why
I have been forecasting weather along the Central Coast since 1991. But I’ve never before seen a mesoscale subtropical storm intensify and expand the way it did as it moved northward toward the Bay Area early Aug. 16.
The storm produced thousands of lightning strikes over the coastal mountains of Northern and Central California. Those peaks do not usually see thunderstorms, unlike the high Sierra Nevada mountain range.
The outbreak of lightning marked the start of one of the worst heat waves ever to grip the state.
Over that period, daily temperature records fell like bowling pins. Paso Robles Municipal Airport reached more than 110 degrees Fahrenheit three days in a roll, breaking the old daily records.
Paso Robles would have continued to reach 110-degree-plus levels through the week, but extensive smoke kept temperature highs near 100 degrees.
The Cal Poly RAWS station in San Luis Obispo hit 112 degrees on Aug. 18, and the Santa Maria Airport saw five straight days of record-breaking temperatures.
These record-breaking temperatures reduced the moisture levels in vegetation.
This helped hundreds of small lightning-triggered fires in California’s coastal mountain ranges to rapidly grow and merge into huge complexes that became some of the biggest blazes California has ever seen. As of Monday, these fires had burned more than a million acres.
By mid-week, smoke from these fires covered nearly the entire western United States.
In fact, many Central Coast locations reported the worst air quality readings on Earth. I have never seen anything like it.
So why are we witnessing such severe conditions? It is probably because of increased levels of carbon dioxide (CO2), and here is why.
Hawaii’s Mauna Loa Observatory, which has monitored CO2 concentrations since 1958, reported a level of 417 parts per million (ppm) in May, the highest monthly CO2 level ever recorded.
For reference, the measurements taken at the observatory back in the late 1950s were around 315 ppm. We are now at levels not seen in the atmosphere in several million years.
As retired U.S. Navy Admiral David Titley will tell you, “To compare that to something readers may be familiar with, a blood alcohol level of .04 percent or 400 (parts per million) puts a partygoer well on their way to intoxication. If we increase our blood alcohol to 800 ppm or .08 percent, we are legally impaired.”
These increased amounts of CO2 are producing record-high atmospheric and oceanographic temperatures, which in turn has increased the severity of storms.
Many climate models predict that the North American monsoon will move farther northward each decade, increasing the likelihood of thunderstorms during the summer and fall.
The increased amounts of CO2 are also causing changes in plant growth.
Though the miracle of photosynthesis, plants take CO2 from the atmosphere, light from the sun and water from the ground and convert them into chemical energy. When you pick up a piece of wood, like a log or a 2-by-4, it is mostly made of carbon removed from the air we breathe.
Nearly all plants use CO2 to grow. Some plants use the extra CO2 much more successfully than others.
Many species of foliage that grow in our coastal mountain ranges contain volatile oils. They’re are now growing faster and bigger during the rainy season.
Unfortunately, this vegetation later becomes explosive fuel for fires in the summer and fall, and even into the early winter.
The Toxicodendron family of plants that encompasses poison oak, Ivy and sumac is among the most effective in utilizing the extra CO2, allowing the plants to produce higher amounts of urushiol oil, according to a U.S. Department of Agriculture study.
Not only does the urushiol become more concentrated, but the plants also produce more leaves -- a double whammy!
A dose as low as 50 micrograms — less than a grain of salt — can cause severe reactions.
Poison oak can be quite dangerous because the allergens can be inhaled, causing lung irritation and scarring. That affects firefighters and others exposed to the burning plant, Dr. Penny Borenstein, San Luis Obispo County public health officer, told me.
How to reduce wildfire risks
With the increased wildfire threat our state faces, PG&E is enhancing and expanding our efforts to reduce wildfire risks and keep our customers and communities safe. Please visit www.pge.com for information.