… and I thought wildfires are a third world problem
When I was in elementary school, I loved watching the wildlife documentaries by Bernhard Grzimek. He was a zoo director and spent time in the Serengeti to film wildlife for the German TV. His documentaries often included scenes of animals running away from wildfires.
As a kid, I thought of these wildfires as a third world country issue until the 1976 drought in Germany when the Lüneburger Heide burned. I realized that an extended drought plus a lightning strike and/or human failure can set a fire. Wind and flash-overs spread it. However, a wildfire wasn’t a normal.
When the smell of smoke wakes you up and it is a normal
Things changed drastically after our move to Alaska. Saturday night we woke up to the smell of fire. After closing the window, we turned around and continued sleeping. After living in Interior Alaska for 15 years, you know that after a week of dry, warm weather in summer, lightning will cause wildfires somewhere in Interior Alaska, and that the air will smell downwind like you put your nose into an open fire place. Tweet about this.
Interior Alaska is wildfire-prone
Lightning caused wildfires have been a natural and dominant disturbance regime in the boreal forest of the Interior for millennia. The wildfires play an important natural role in its ecosystems. However, in Alaska and Northern Canada, the area of boreal forest burned annually has doubled in the last three decades.
The 2004 wildfire caused hazardous air-quality
In 2004, Interior Alaska faced the strongest fire season since onset of recording in 1940. About 6 671 845.3 acres (2 700 000 hectare, 27 000 km2) forests burned. Thick smoke layers of large horizontal and vertical extension covered Interior Alaska. On some days, the smoke reduced the visibility to several tens of meters and even led to restrictions on air traffic.
People wore masks to at least filter out some of the ash, black carbon and other particles. Nevertheless, you could smell the volatile organic compounds (VOC) and the ozone that formed from the precursor gases emitted by the wildfires.
The concentrations of particles with 2.5 micrometer or less in diameter (so-called PM2.5) were so high that the instrument could not measure them, i.e. over 1000 microgram per cubicmeter, which was the uppermost limit the instrument could measure. Note that the US EPA National Ambient Air Quality Standard (NAAQS) for the 24 hour and annual means of PM2.5 are not to exceed 35 and 15 microgram per cubic meter, respectively. PM2.5 concentrations remained at health threatening levels (175 microgram per cubic meter) for several weeks.
The 2004 wildfire season evidenced that even in a remote and otherwise pristine region like Interior Alaska serious air quality problems can occur. In Interior Alaska, the biomass burning emits carbon monoxide (CO), carbon dioxide (CO2), methane (CH4), non-methane hydrocarbons (NMHC), polycyclic aromatic hydrocarbons (PAH), nitric oxide (NO), nitrous oxide (N2O), carbonyl sulfide (COS), and particulate matter (PM).
Moreover, wildfires release huge amounts of water vapor (H2O) because they heat the underlain permafrost, and thaw some of the permafrost. The resulting soil water evaporates or the soil ice may even directly sublimate to water vapor.
The gases and particles released by wildfires chemically react with trace species naturally available in the atmosphere. Some of the gases photo-dissociate by solar radiation during the long daylight hours and produce free radicals. The emitted gases and radicals also react with VOCs emitted naturally by the deciduous and coniferous trees of the Interior.
Smoke reduces visibility
In the atmosphere, water-soluble particles take up water vapor and swell thereby reducing the visibility in addition to the ash and non-water soluble particles. When small droplets form, the solution will also undergo chemical reactions.
Cleansing becomes a burden for ecosystems
The pollutants are removed from the atmosphere by rain, particle sedimentation, and dry deposition of gases. Acid rain is the result of in-cloud and below cloud scavenging of the pollutants. The removal of the pollutants from the atmosphere represents a burden on the ecosystems and natural water systems. Since the peak number of wildfires occurs in summer when insolation and, hence, available energy for photochemical processes is high, the impact on ecosystems and air quality will be the strongest in this season, too.
Wildfire smoke undergoes long-range transport
The wildfire smoke and pollution affects more people than just Alaskans. In the 2004 wildfire season, for instance, the smoke penetrated into Denali National Park, Arctic National Park, the Yukon Flats National Wildlife Refuge, and the Arctic National Wildlife Refuge. In summer, these areas have many visitors. Tweet about this.
2010 Goldstream fire
When you already follow this blog for a while, you know that we lived in the Goldstream Valley in our first years in Alaska. The fire in the photos burned in 2010 close to where we had lived. We had seen the fire from far and drove close to it as we still knew a lot of people in our former neighborhood. When we parked at Ivory Jack, the brother of our former landlord was there too. He was one of our closest neighbors back when we lived there. He came to our car and said “Your house is fine and so is everyone. The fire is farther north and propagates north as well.”
Later in the evening, we met a couple from our former neighborhood at a social dance. “Did they extinguish the fire already?” “Nope. We drove the photos and computers to our children’s house. There is no need to wait until they force us to evacuate. What can we gain by staying at home?” they said and danced the night away. P.S. Their house did not burn down.
Are there wildfires in the area you live? Are they an annual annoyance or occur one a decade? When you don’t live in an area with wildfires can you image the stink and thread they pose? Let me know by email, I am curious.
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Photos: G. Kramm
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