USA – California’s historic 2020 wildfires released a staggering amount of planet-warming greenhouse gases into the atmosphere, but that may not be as big of a problem as it sounds, according to state officials and climate experts.
As of mid-October, fires in the state had produced more carbon dioxide than every economic sector except transportation.
Wildfires emitted 111.7 million metric tons of carbon dioxide, according to preliminary figures provided by the California Air Resources Board, compared with 169.5 million metric tons of carbon dioxide equivalent for transportation in 2018, the most recent year for which greenhouse gas figures are available by sector.
Yet experts say that wildfire emissions should not be compared in an apples-to-apples fashion with emissions caused by cars, power plants and other sectors that burn fossil fuels for energy.
That’s not because the emissions from fires do not trap heat in the atmosphere — they do. Rather, it’s because fire is a natural part of the landscape in California, meaning that some amount of greenhouse gases should be expected every year because of wildfires. Also, the carbon released by a forest when it burns got there because trees took it from the atmosphere — as they’ll do again when vegetation regrows.
“The forests are alive. They’re growing and dying and regrowing,” said Michael Wara, director of the climate and energy policy program at Stanford University’s Woods Institute for the Environment. “That’s really different than carbon that was buried 50 million years ago under the earth that we are unearthing and burning. I think it’s not helpful to compare the two. It’s a misdirection.”
Forests typically take decades to fully regrow after being scorched severely in a wildfire, yet their ability to recapture carbon through photosynthesis is considered part of the Earth’s natural carbon cycle.
The air board has been tracking wildfire emissions and is working to deepen the public’s understanding of how the carbon dioxide released by blazes in recent years compares with what California experienced historically. A public webinar on the subject occurred Tuesday.
The air board’s past figures show that 2020 was far more intense a time for wildfire carbon emissions than any other year in which records were kept, which is as far back as 2000. This year’s fire-related emissions were significantly more than double the respective totals in 2018 and 2008, which saw two of the most severe fire seasons before this year. The 2020 estimate is also greater than the carbon estimates for fires in 2016 through 2019 combined.
That’s not surprising, because this fire season has seen far more acres burned than any other year on record, with more than 4 million acres burned across the state.
Higher carbon emissions generally coincide with years where more land burned.
While carbon dioxide is the primary greenhouse gas tracked by the air board in its wildfire emissions tally, fires can also release other planet-warming pollutants such as methane, experts say.
Air board officials are trying to get a better understanding of how much fire California historically saw before the modern era, including through cultural burning practices by Native American tribes. Further work is needed to arrive at a more conclusive answer, said Dave Edwards, assistant division chief of the air board’s air quality planning and science division.
“The ultimate goal would be to put some context around today’s fire,” Edwards said in a recent interview.
Air board officials said at the webinar that they hope to have reports on fire emissions and historical fire activity in California finalized by mid-2021.
Tony Wexler, director of the Air Quality Research Center at UC Davis, said carbon emissions from wildfires are “pretty close to a zero concern for me.”
“The carbon in the trees and brush and grasses that’s burning all came from the atmosphere,” Wexler said. “It’s not a net emission of carbon dioxide — it’s basically putting it back where it came from. I don’t consider this to be a serious problem for climate.”
Wexler is more concerned about the health impacts of pollution caused by wildfire smoke — which was particularly bad in California this year, when the air was unhealthy for weeks.
The problem of wildfire emissions, both the planet-warming kind and the particulate matter pollutants that can cause coughing and long-term lung damage, is made worse by climate change, which is drying out trees and shrubs more and fostering other conditions that make fires more likely to grow into vast, raging infernos.
California could get a better handle on its wildfire problem by stepping up its prescribed fire program, as the state has now committed to doing. Wexler said he also supports using more forest land to harvest biofuels, which turns organic materials into energy. Thinning forests can make future fires less severe.
Wara, the Stanford climate expert, said he has been trying to secure funding — so far unsuccessfully — to research how the state’s big fire-prevention plans might affect smoke levels going forward. Using models typically applied to parse out the impact of new regulations on air pollution, Wara wants to project how California’s plans to dramatically expand its prescribed fire program could affect the amount of smoke seen in the state every year.
Though he said he doesn’t think fire emissions should be compared to those from fossil fuels, Wara said it’s still useful to contemplate how land management practices can influence how long forests retain the carbon they store before releasing it back into the atmosphere.
“That’s not a scary thing to consider, but it’s just really different than coal and gas or oil,” he said.