by University of California – Irvine, Mar 3, 2023 in ScienceDaily

Nearly half a gigaton of carbon (or 1.76 billion tons of CO₂) was released from burning boreal forests in North America and Eurasia in 2021, 150 percent higher than annual mean CO₂ emissions between 2000 and 2020, the scientists reported in a paper in Science.

“According to our measurements, boreal fires in 2021 shattered previous records,” said senior co-author Steven Davis, UCI professor of Earth system science. “These fires are two decades of rapid warming and extreme drought in Northern Canada and Siberia coming to roost, and unfortunately even this new record may not stand for long.”

The researchers said that the worsening fires are part of a climate-fire feedback in which carbon dioxide emissions warm the planet, creating conditions that lead to more fires and more emissions.

“The escalation of wildfires in the boreal region is anticipated to accelerate the release of the large carbon storage in the permafrost soil layer, as well as contribute to the northward expansion of shrubs,” said co-author Yang Chen, a UCI research scientist in Earth system science. “These factors could potentially lead to further warming and create a more favorable climate for the occurrence of wildfires.”

Davis added, “Boreal fires released nearly twice as much CO₂ as global aviation in 2021. If this scale of emissions from unmanaged lands becomes a new normal, stabilizing Earth’s climate will be even more challenging than we thought.”

Analyzing the amount of carbon dioxide released during wildfires is difficult for Earth system scientists for a variety of reasons. Rugged, smoke-enshrouded terrain hampers satellite observations during a combustion event, and space-based measurements are not at a sufficiently fine resolution to reveal details of CO₂ emissions. Models used to simulate fuel load, fuel consumption and fire efficiency work well under ordinary circumstances but are not robust enough to represent extreme wildfires, according to the researchers.

…