The month of September has only begun, but so far the U.S. Climate Prediction Center has hit the bullseye – warmer, as it has been all summer, and wetter, hopefully marking the start of the end to what has qualified as a drought in Gulf Coast Alaska.
A drought along the rugged Alaska coast is not, however, like a drought in the Dust Bowl. The swamps are still wet and most of the creeks still run. When the drought reached the level of “extreme” in parts of the state’s Pandhandle, it meant annual rainfall had decreased from 150 inches per year to 100.
A hundred inches of rain would make for a wet year in most places, but in the temperate rain forest it is a dry season.
Further to the north and west, where annual rainfall is less, a dry spell that started in mid-July pushed the normal precipitation level for the area in and around Alaska’s largest city far behind the curve by the beginning of September.
Annual precipitation at the start of the month stood at 5.93 inches, according to the National Weather Service; well below the average of 9.4 inches but still significantly above the 4.62 inches in 1969.
Back in the halcyon days of the ’60s when “climate change” had yet to become a catchphrase, a sunny season with less than 5 inches of rain constituted a summer to die for. Now, with global-warming fears on the rise, a season with less than 6 inches causes some to worry about signs of the apocalypse.
“Alaska Is on Fire,” Vice News headlined above a report that “drought in the state, on the scale the state has seen this summer, is unprecedented” except for those who were already in the state in ’69.
Still, with the smoke-filled air in the state’s largest city in August sometimes making it look like a Chinese metropolis, there were some days cause for serious concern about air quality, and a lot of fretting about what it all means for the future.
Both served to take the joy out of what might otherwise have been considered a long run of beautiful weather.
“About 2.5 Million Acres in Alaska Have Burned. The State’s Wildfire Seasons Are Getting Worse, Experts Say,” Time magazine headlined a story in which had Scott Rupp, deputy director of the International Arctic Research Center at the University of Alaska Fairbanks, warning that “not only are the conditions for severe fire seasons becoming more common, but major fires pump greenhouse gases into the environment. Boreal forests are usually a ‘carbon sink’ that absorbs carbon, but when they burn too frequently they can become a ‘carbon source.’
“We’re increasing greenhouse gases, which leads to more warming, which leads to more fires.”
Except the latest research says it’s not quite that simple, as is the case with much in the earthly carbon cycle.
First off, forest fires have generally been thought to be largely carbon-neutral because – as is the case in much of Alaska now – they tend to consume old, dead trees which are doing little to remove carbon dioxide from the atmosphere.
Photosynthesis is the planet’s “life support system” as New Scientist notes. Plants on both and land and in the water, along with some algae and bacteria, take in CO2 and water and use solar energy to turn it into the carbohydrates with which they feed themselves.
One of the by-products of that process is oxygen, which humans and all the rest of the animals of the planet need to survive. Not to mention that plants are near the base of food chain that feeds all animals.
Thus young forests actively engaged in CO2 uptake are better than old or worse yet, dead forests such as those that caught fire on the Kenai Peninsula south of Anchorage this summer.
But new research is documenting a forest carbon cycle far more complicated than just the trade-offs between carbon releases in forest fires and carbon uptake and sequestration in new, young forests.
First off, there is fresh research out of Idaho indicating that forest fires might not be releasing nearly as much CO2 as once feared.
Reporting in Global Change Biology in May, Jeff Stenzel and colleagues at the University of Idaho observed that “that regional emissions estimates using widely implemented combustion coefficients (for climate models) are 59 percent to 83 percent higher than emissions based on field observations….Most model development focuses on area burned; our results reveal that accurately representing combustion is also essential for quantifying fire impacts on ecosystems. Using our improvements, we find that western U.S. forest fires have emitted 851 ± 228 teragrams (Tg) CO2 (approximately half of alternative estimates) over the last 17 years, which is minor compared to 16,200 Tg CO2 from fossil fuels across the region.”
Fires sequestering carbon
This is, however, only one new complicating factor in trying to figure out the big picture meaning of forest fires in the carbon cycle. European scientists just last month reported forest fires can actually increase carbon storage and thus help reduce CO2.
In the process of scorching 1.2 million to almost 2 million square miles of the earth’s surface every year, Matthew Jones from Swansea University in the United Kingdom and colleagues reported, forest fires create a significant amount of what is called “pyrogenic carbon.”
“Pyrogenic carbon can be stored in terrestrial and marine pools for centuries to millennia and therefore its production can be considered a mechanism for long-term carbon sequestration,” they wrote in a peer-reviewed paper published by Nature Geoscience.
The group estimated that 256 teragrams of carbon was converted into pyrogenic carbon between 1997 and 2016.
“Our central estimate equates to 12 percent of the annual carbon emitted globally by landscape fires, which indicates that their emissions are buffered by pyrogenic carbon production. We further estimate that cumulative pyrogenic carbon production is 60 petagrams (a teragram times 10) since 1750, or 33 to 40 percent of the global biomass of carbon lost through land-use change in this period.
“Our results demonstrate that pyrogenic carbon production by landscape fires could be a significant, but overlooked, sink for atmospheric CO2.”
As Jones told European Scientist, “CO2 emitted during fires is normally sequestered again as vegetation regrows, and researchers generally consider wildfires to be carbon neutral events once full biomass recovery has occurred,” but no one ever gave much thought to the charcoal left behind as soot or charred tree remains.
Pyrogenic carbon has been getting considerable attention on several fronts in Europe. Hans-Peter Schmidt from the Ithaka Institute in Hamburg, Germany and colleagues last year suggested it as possible means to capture and store carbon.
“…Biomass carbon (think dead trees) is easily degraded by microorganisms releasing it in the form of greenhouse gases back to the atmosphere,” they observed in a peer-reviewed paper published at Global Change Biology-Bioenergy. “If biomass is pyrolyzed, the organic carbon is converted into solid (biochar), liquid (bio‐oil), and gaseous (permanent pyrogas) carbonaceous products. During the last decade, biochar has been discussed as a promising option to improve soil fertility and sequester carbon….”
Mother Nature has been doing significant pyrolyzing in Alaska this year, but whether she is helping push back against climate change, accelerate climate change, or neither appears in hard to say without better research.
U.S. Department of Agriculture scientists who closely studied fires in California last year concluded that the “poor relationships between carbon and pyrocarbon gains or losses and fire severity highlight the complexity of fire impacts on forest carbon.”
The California fires, they reported, released about 85 percent of the carbon in understory growth and tree leaves in the form of CO2, the main gas given off in all combustion. But overall “carbon emissions represented only 21.6 percent of total forest carbon.”
Meanwhile, they said, “fire resulted in a net ecosystem pyrogenic carbon gain.”
As with most things climate-related, it’s complicated and largely a distraction from the significant climate-change issue: The large volumes of carbon sequestered underground as crude oil or coal before being uncovered by humans and converted to atmospheric CO2.
Forest fires cans emit a lot of CO2 in a short period, but regrowth forests can similarly suck up a lot of CO2 in over a relatively short time. Human activities release a lot and don’t suck up much, though there are people working on the latter, including a California company – Blue Planet – sorting out how to economically capture CO2 and transform it into carbonate rocks to be used as an aggregate in concrete.
Think of the irony there. More pavement as an antidote to climate change. But Blue Planet isn’t the only company with an idea for turning the pollutant into a resource as Engineering and Technology Reports.