Wildfires in 2021 emitted a record-breaking amount of carbon dioxide
UC Irvine-led study found northern-latitude forest fires to be the
highest source

Date:
March 3, 2023
Source:
University of California - Irvine
Summary:
Carbon dioxide emissions from wildfires, which have been gradually
increasing since 2000, spiked drastically to a record high in 2021,
according to an international team of researchers.


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FULL STORY ========================================================================== Carbon dioxide emissions from wildfires, which have been gradually
increasing since 2000, spiked drastically to a record high in 2021,
according to an international team of researchers led by Earth system scientists at the University of California, Irvine.


========================================================================== 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.

And there is another roadblock of our own creation. "Earth's atmosphere
already contains large amounts of carbon dioxide from human fossil fuel burning, and the existing greenhouse gas is difficult to distinguish
from that produced by forest fires," said Chen.

The team found a way around these hurdles by studying carbon monoxide
expelled into the atmosphere during blazes. Combining CO readings from
MOPITT -- the Measurements Of Pollution In The Troposphere satellite
instrument -- with existing fire emissions and wind speed datasets,
the team reconstructed changes in global fire CO2 emissions from
2000-2021. Carbon monoxide has a shorter lifespan in the atmosphere than
CO2, so if scientists detect an anomalous abundance of CO, that provides evidence of fires.

The researchers independently confirmed the occurrence of extreme fires
in 2021 with data sets provided by NASA's Moderate Resolution Imaging Spectroradiometer aboard the Terra and Aqua satellites.

"The inversion approach employed in this study is a complementary
method to the conventional bottom-up approach, which is based on
estimating the burned area, fuel load, and combustion completeness,"
Chen said. "Combining these approaches can result in a more comprehensive understanding of wildfire patterns and their impacts." The researchers
said their data analysis revealed links between extensive boreal fires
and climate drivers, especially increased annual mean temperatures and short-lived heat waves. They found that higher northern latitudes and
areas with larger tree cover fractions were especially vulnerable.

"Wildfire carbon emissions globally were relatively stable at about 2
gigatons per year for the first two decades of the 21st century, but
2021 was the year when emissions really took off," David said. "About
80 percent of these CO2 emissions will be recovered through vegetation regrowth, but 20 percent are lost to the atmosphere in an almost
irreversible way, so humans are going to have to find some way to remove
that carbon from the air or substantially cut our own production of
atmospheric carbon dioxide."
* RELATED_TOPICS
o Earth_&_Climate
# Wildfires # Global_Warming # Forest # Climate #
Air_Quality # Natural_Disasters # Environmental_Issues
# Earth_Science
* RELATED_TERMS
o Climate_change_mitigation o Carbon_dioxide_sink o Forest
o Climate_model o Carbon_dioxide o Ocean_acidification o
Fossil_fuel o Carbon_monoxide

========================================================================== Story Source: Materials provided by
University_of_California_-_Irvine. Note: Content may be edited for style
and length.


========================================================================== Journal Reference:
1. Bo Zheng, Philippe Ciais, Frederic Chevallier, Hui Yang, Josep G.

Canadell, Yang Chen, Ivar R. van der Velde, Ilse Aben, Emilio
Chuvieco, Steven J. Davis, Merritt Deeter, Chaopeng Hong, Yawen
Kong, Haiyan Li, Hui Li, Xin Lin, Kebin He, Qiang Zhang. Record-high
CO 2 emissions from boreal fires in 2021. Science, 2023; 379
(6635): 912 DOI: 10.1126/ science.ade0805 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2023/03/230303105251.htm

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