Fire hastens permafrost collapse in Arctic Alaska

Date:
December 9, 2021
Source:
University of Illinois at Urbana-Champaign, News Bureau
Summary:
While climate change is the primary driver of permafrost degradation
in Arctic Alaska, a new analysis of 70 years of data reveals
that tundra fires are accelerating that decline, contributing
disproportionately to a phenomenon known as 'thermokarst,' the
abrupt collapse of ice-rich permafrost as a result of thawing.



FULL STORY ========================================================================== While climate change is the primary driver of permafrost degradation in
Arctic Alaska, a new analysis of 70 years of data reveals that tundra
fires are accelerating that decline, contributing disproportionately
to a phenomenon known as "thermokarst," the abrupt collapse of ice-rich permafrost as a result of thawing.


========================================================================== Reported in the journal One Earth, the study is the first to calculate
the role of fire on permafrost integrity over so many decades, the
researchers say.

The Arctic permafrost is a vast storehouse of frozen plant and animal
matter, a carbon stockpile that, if thawed and degraded, could more than
double the amount of carbon in the atmosphere, researchers say.

"This process, because it's very unpredictable, is poorly understood,"
said Yaping Chen, a former graduate student at the University of
Illinois Urbana- Champaign, who led the research with Mark Lara, a
U. of I. professor of plant biology and of geography and geographic
information science, and Feng Sheng Hu, a U. of I. professor emeritus
of plant biology and current dean of arts and sciences at Washington
University in St. Louis.

"With this study, we're advancing our understanding of the permafrost ecosystem," said Chen, now a postdoctoral researcher at the Virginia
Institute of Marine Science in the College of William and Mary.

The team analyzed seven decades of air and satellite imagery to calculate
the rate of thermokarst formation in different regions of Arctic Alaska.

Researchers also used machine-learning-based modeling to determine the
relative contributions of climate change, fire disturbance and landscape features to observed permafrost declines.

"We found that thermokarst formation has accelerated by 60% since
the 1950s," Chen said. "Although climate change is the main driver of thermokarst acceleration, fire played a disproportionately large role in
that process. Fire burned only 3% of the Arctic landscape in that time
period but was responsible for more than 10% of thermokarst formation." Repeated fires in the same areas continued to damage the tundra but did
not further accelerate thermokarst formation, the researchers found. The
study revealed that a single fire could accelerate thermokarst formation
for several decades.

"Models predict that thermokarst will only increase with climate change,"
Lara said. "In addition to thawing permafrost, climate warming dries
out the tundra, increasing its flammability. This makes it more likely
that lightning strikes will spark fires, causing even more permafrost degradation." Thawing and collapsing permafrost also leads to other
landscape changes, Lara said. For example, lakes sitting in frozen
permafrost depressions may drain - - gradually or suddenly -- when that permafrost degrades.

"The loss of permafrost can open up the floodgates of environmental
change," he said.

The National Science Foundation supported this research.

========================================================================== Story Source: Materials provided by University_of_Illinois_at_Urbana-Champaign,_News_Bureau.

Original written by Diana Yates. Note: Content may be edited for style
and length.


========================================================================== Related Multimedia:
* Permafrost_degradation_in_northern_Alaska ========================================================================== Journal Reference:
1. Yaping Chen, Mark J. Lara, Benjamin M. Jones, Gerald V. Frost,
Feng Sheng
Hu. Thermokarst acceleration in Arctic tundra driven by
climate change and fire disturbance. One Earth, 2021; DOI:
10.1016/j.oneear.2021.11.011 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/12/211209124225.htm

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