Upcoming Dryness (More Danger?)
Blog #86, CaliforniaGeo 4-7-22
Plumas (recent) fire history-
Where I live in Quincy, California, we’ve been threatened by wildfire three times in the past five years and we evacuated twice. The largest and longest danger we endured was from the Dixie Fire from mid-July to late-October, 2021. By the time of its containment its staffing had dropped to 645 from over 6,000 for much of its run. We lost much of the town of Greenville and nearly all of two other nearby communities.
Seventy percent of the Plumas National Forest was burned. The Bucks Lake and Caribou Wilderness areas were mostly burned, as was 66 percent of Lassen Volcanic National Park. Previously, in June of 2021, the southeast corner of Plumas County suffered an 83,000 acre fire named the Beckwourth Complex (meaning it encapsulated at least two fires within its ultimate boundary). We thought we had completed the fire threat when that was over—but the Dixie came out to remind us we were far from done for 2021.
Factors for acceleration-
Everyone is probably familiar with the struggle to get a campfire going when desired. Dry softwood can ignite at 425°F and a kitchen match can sustain that long enough with help from kindling for generating flames from wood. That’s an ignition event. Wildfire keeps going when fire escapes and spreads out, pre-heating available fuel as it goes. Add some wind and/or a delay in suppression, and that fire moves faster. Do that over a soil that cannot evaporate moisture to increase humidity and through fuels that are drier than they’ve ever been and you can get a real monster we call a conflagration.
More of us in this era of instant news are familiar with firefighting activity and its various tools for suppression. But what we can forget when focusing on our own nearby fire, is that the woodland agencies we depend on have multiple other fires going that demand a share of resources. There are now more jet-powered air tankers than ever, but they can’t all be at the same place at once. They must be rationed—and suppression suffers when this happens.
The well-known Fire Triangle has three components; fuel, heat, and oxygen. All three are necessary for combustion to be sustained. Those familiar with the use of an acetylene cutting torch will recall that it’s the addition of pressurized oxygen that produces a hotter flame. Strong winds blown into wildfires can push them to gobble up more acres per hour. We’ve known about the famed southern California Santa Ana winds for years as an example of this.
In recent years we’ve had increased wind velocities in summer and the Dixie Fire performed its imitation of a torch when it consumed 104,000 acres in a single day on August 4th. Local pyro-cumulus clouds helped make that possible. They work like a thunderstorm but with no relief! Vertical updrafts from the hot fire pulls in replacement air from the side. When firebrands get to an altitude where gravity overcomes upthrust, they all cascade downward with most still carrying embers that ignite forest fuels when they strike the ground, moving in every direction. A very wide peripheral “front” from this is what discharged near Greenville and kept pushing so fast that no suppression team could stand and fight such a hot, fast approaching wall of flame.
What about 2022?
We are in worse shape than at this time last year. Precipitation remains a fraction of long-term “normal.” On April 1st, the Water Resources snow course at Phillips Station (6,800 feet) showed just 4% of normal snowpack. The northern Sierra (all stations and elevations) showed 28% of water content within the snowpack for that date.
December, 2021 produced a new, all-time record for snowfall in the Sierra, but that is now all gone due to storms diverting elsewhere. There is little chance that between now and the end of the precipitation year (Sept. 30th) we will get any closer to normal.
What can be done? My favorite reminder about building more dam-based water storage (from a friend) is the statement, “Pouring concrete won’t make it rain.” Normally and historically, the Sierra’s snowpack has been the biggest reservoir of water for us but the increased “intermittency” of normal precipitation years is erasing that. And this extends to forest soils, the humidity in their vicinity, and moisture levels in forest fuels themselves—all of which can influence fires and conflagrations.
Highs are already breaking 90° in Sacramento. This year, there is less ground moisture whose surface evaporation and plant transpiration from underground could temper that heat. As this drier than normal season continues, we’ll experience a greater number of high temperatures with increased winds. Both conditions combine to make fires burn hotter and to pre-heat heavy forest fuels as a fire front approaches.
Below is a montage of Sierra snowpack images, all taken on a date five weeks earlier than the image above. There is great variation. What can’t be shown from an image is whether or not somewhat normal rainfall followed throughout each spring. For precision, it might be better to take a look at reservoir levels around May 15th, but we have had years in which early high heat has melted Sierra snows more quickly, or has sublimated a greater percentage of them into eastbound air flows. [Sublimation is the direct evaporation off snowpack by evaporation, thereby skipping the phase change to liquid.] In such cases, reservoirs would receive less runoff, unless late season rainfall were to compensate.
A fast dry out is always possible and can change fire danger very quickly. We must work harder to be ready for that.
We can’t control daily weather or the changes in climate that are bending historical normal seasons into various records. There is likely some level of climate change already “baked-in” to our system.
[Carbon dioxide levels are proven to be far higher now than at any time in the last 800,000 years, courtesy of air bubble analysis from Greenland ice cores. So this means that the industrial revolution, increased world population, and higher living standards since, are responsible for the rise.]
But relative to wildfire, things are a bit different. We cannot control or stop ignition events but there are two other things we can do.
First, fires slow or die without adequately dense fuel. If we can slow fire spread and intensity by thinning, the fixed suppression resources we are forced to ration will be able to do a better job to shorten the lives of fires like the Dixie, which marched on for over three months. Threats to lives and damage to property could be reduced. The wheel doesn’t have to be invented from scratch. A local assortment of interested citizens self-named The Quincy Library Group built an effective program that received congressional and White House approval in 1998. It combined good silviculture for the Sierra Nevada Mixed Conifer type with shaded DFPZs (defensible fuel profile zones) that were proven effective to slow approaching wildfire adequate for conventional ground forces to control them, often letting ground fuel burn to reduce future danger and convert surface nutrients for use by roots, underground.
It was to be a 10-year treatment program with follow-up monitoring. Unfortunately, environmentally aligned citizens tend to see every instance of chainsaw or feller-buncher work in the woods as “logging” for profit. Fights over utilization of commercially viable materials to offset the treatment costs ensued, along with multiple lawsuits. Public money alone for this purpose (even if unopposed) was accurately described as “welfare forestry.” No matter how small the treatment projects were sequenced, some fought this as unwise. The U.S. Forest Service did not take an effective leadership position in this program, and less acreage received treatment across the Lassen, Plumas, and Tahoe National Forests. Those who watched the Dixie race last summer may always wonder if it might have been slowed by thinning treatment.
The second thing we can do is think differently about buildings and housing in areas referred to as the WUI (wildland urban interface). Fuel clearance standards have been advocated by professionals for a long time but are routinely ignored by people who moved to the mountains to live “among their trees.” Better construction codes for windows, siding, and attic venting joined prior roof regulations in 2008 that made for more defensible buildings. Zoning regulations for new construction could keep subdivisions even safer, in part by under grounding electrical lines and strategizing improved traffic flows in advance to save lives in an evacuation. More attention to this could help slow fire insurance rate increases for all of us.
It’s looking to become another rough fire season, with lots of money spent on combat. Our options are limited because of so much that has been done without adequate regard for wild land management and for missed opportunities and the consequences that brings. The sooner we reduce carbon in the atmosphere, the more defensible our climate could be. Decarbonization in all occupied buildings can join with greater fractions of renewable electricity to make a substantial difference. Geo heat pumps help us get the earth involved in solving the very problem of preserving it. Plan ahead. Stay safe.