In we breathed wildfire smoke, out the forests released carbon — a record setting amount, of course
Forests burn. Carbon emits. Climate warms. Repeat.
Thalia Dockery was on a flight from San Jose to Las Vegas after visiting with family. She forgot her headphones and turned to gaze out the window when she sat up in her seat and started fumbling for her phone. A plume of dense smoke in terrifying proportions, nearly nine miles high, billowed near the wing of the plane.
“It was a bit ominous,” Dockery told me in a direct message. “I thought it was just a huge cloud. Then I looked at the bottom, and it reminded me of a tree with roots. I didn’t realize until we got home, and my son and I started researching cloud formations that it was from the Creek Fire.”
The tempest spun up from a fire-fueled thunderstorm above California’s Sierra National Forest, earning the name fire-breathing dragon of clouds among meteorologists. It’s a record large pyrocumulonimbus storm now chronicled in a growing list of historic, dare say unprecedented, events of 2020 in the United States.
Smoke from wildfires that devastated the entire West Coast spread to the East Coast, where Doug Morton, Chief of the Biospheric Sciences Laboratory at NASA, watched the sunset against a hazy horizon every day for a week at his home in Washington D.C. I gave him a call.
“There are a number of surprising things about the fires in the western United States this year, even for scientists like myself that have spent many years studying fires and fire emergencies across the world, and the potential for these extreme fire events to be releasing so much energy that they loft smoke high into the stratosphere is one of the kind of hallmark signs of this new extreme wildfire behavior,” Morton said.
“From an earth system perspective, when the smoke reaches those higher altitudes … it changes the chemistry and the forces at work in terms of how long the gases will last in the atmosphere, and obviously allows those greenhouse gases and the smoke particles to be transported much further downwind,” Morton said. “And the combination of those two things, the sort of larger spread of the smoke plume, and a longer lifetime of smoking atmosphere.”
West Coast communities already teetering with fragile public health now faced another layer of challenges in social distancing with a wildfire and smoke crisis; some were forced to stay indoors to safeguard against the hazardous air, while others didn’t even have a home to return to.
When it was among the worst in the world, spending the day outside was like smoking nine cigarettes, inhaling dangerous particulate matter that could exacerbate any underlying health issue, now possibly including COVID-19 symptoms.
But the smoke’s impact doesn’t end there. It also translates into significant carbon emissions, a greenhouse gas that wraps itself around the earth like a thick blanket, warming it.
In the other Washington, the state is on trajectory for wildfire smoke to be the second largest category of carbon emitters in 2020, with carbon emission from transportation taking first place. In 2015, during the state’s worst wildfire on record in recent years, emissions from wildfires were about 25 percent of Washington’s human-generated greenhouse gas emissions.
Meanwhile, its neighbors, California and Oregon, are reaching the highest amounts of carbon emissions from wildfires than ever before, according to the Global Fire Emissions Database (GFED).
As wildfire seasons become longer and more intense, more people want to understand emissions that come from wildfires. To do that, we turn to natural carbon cycles.
“We’ll use a forest, but it can be other ecosystems that take in carbon dioxide,” said Nancy French, a senior research scientist studying fire emissions at Michigan Tech Research Institute. “You know, we take in oxygen and breathe out carbon dioxide. Trees do that too, and microbes.”
Microbes live in the soil, composed of wood, leaves, and tree needles that dropped to the forest floor — decomposing and giving off carbon.
“Because they’re little, tiny animals, think of the microbes in the soil, they’re actually breathing and giving off the carbon. So it’s, that’s called heterotrophic, it’s the respiration that’s coming from the ground itself. You slowly get this place that grows more and more carbon, but it’s going in and out, you know, because you got respiration,” French said.
“So that’s your normal, and then you get these disturbances. Fire, windthrow, insects, different things, cutting down the forest for use, all those disturbances will just change the entire situation. And typically with a forest, you get things growing back really quickly until you have actually a much more vibrant system. You have a lot more growth in early successional. It’s sucking down the carbon faster when it’s young.”
Much of the carbon released by fires this year will eventually be absorbed by vegetation that regrows in the next couple of years, but the carbon emissions from the combustion of fossil fuels, like some gas, is a permanent release. It essentially doesn’t have a place to return.
Scientists who study consequences of fire for greenhouse gases usually take a look from a global scale to evaluate long-term loss of carbon into the atmosphere.
Deforestation, as seen in the Amazon, results in people burning woody vegetation to expand areas for agriculture. That landscape isn’t going to regrow a forest, and so the carbon emissions from those forests also become permanent. In the case of the western United States, the focus turns to forests and ecosystems that grow slowly. After a large fire, it could take decades to recover the carbon lost, and when the landscape grows back, it will be transformed, meaning the forests may have different characteristics.
“Essentially, we’ll be able to eventually store as much of the carbon as is being burned off and killed by the fires today,” Morton said. “Whereas we once were talking about the conversion process like deforestation as being the major source of long term greenhouse gas emissions, now we’re opening up a conversation about whether fires will create a new kind of ecosystem, and that transition will also lead to this release of greenhouse gases. That puts it right back on par again, with your cars or boats, your planes, your trucks.”
As carbon dioxide concentrations increase in the atmosphere, so will the persistence of blocking patterns, which are centers of high pressures that happen over a region. This pattern, called blocking ridges, prevent other systems from moving through the area. It can further enhance drought conditions and the potential for fire, according to a University of Washington study analyzing the effects of climate change on fire in the Pacific Northwest.
The study reports that fire and drought likely will be the primary drivers of ecosystem change in a warming climate in the West. Reburns will likely become more frequent, with hotter and drier wildfire sites becoming particularly at risk for not being able to regrow and sequester carbon.
“Where we expect to see some potential regeneration failures would usually be at the lower tree line. So that ecotone between where trees are able to live and where they made shrublands or grassland at lower elevations, that could be a net loss in terms of ability to store carbon,” said David Peterson, a forest biology professor at the University of Washington who worked on the study.
“Having said that, grassland soils can also store a large amount of carbon, and they can store it in kind of a more permanent fashion in the soil. So there are some trade offs and all this depends tremendously on which systems we’re talking about.”
In some respect, many of the ecosystems are returning back to what they were hundreds of years ago. In the low tree line that Peterson discussed, those soils indicate characteristics of grasslands, even if trees are on those lands. Aggressive fire suppression tactics in natural resources management resulted in removing natural fire, leading to overgrowth and invasive species.
When measuring the historic events of modern wildfires, researchers look at the geologic time scales that evaluates climate over millions of years. With the combination of a rare wind event and heat, the wildfires right now on the West Coast are an exceptional and anomalous event, but only in the last few hundred years. I asked David to explain the old age burns.
“In the 1800s, and before, for that period of time, we probably had a lot more fire and landscape than we have right now,” Peterson said. “People are talking about how we’re getting six to eight million acres burned a year in the United States, but maybe in the distant past, it was more like 20 million acres or more a year, because there was nobody there to suppress fires. They burned all summer.”
The amount of people coexisting with these conditions is what makes recent events a truly historic moment. Wildfires and its smoke and carbon are an intersectional issue of climate change and people’s way of life.
We’ve reached a tipping point in both a local and global understand of fire and smoke risk in a warming world, because people are now actually seeing the change — whether that’s from watching videos documenting emergencies in the west, scrolling on social media and finding posts of cities covered in smog, or simply looking out the window.
