Arctic Region Becomes Major Carbon Emitter

Expansive regions within one of Earth’s most significant carbon sinks are now emitting carbon dioxide (CO₂) rather than sequestering it. Recent research conducted by an international team, spearheaded by scientists from the Woodwell Climate Research Center in Massachusetts, reveals that over a third of the Arctic-Boreal Zone (ABZ)—comprising tundra, forests, and wetlands encircling the Arctic Circle—has transitioned to a net carbon source.

This alarming shift is also evident in certain areas of the Amazon Rainforest. While the ABZ continues to be classified as a carbon sink overall, a historic role it has played for millennia, the escalating global temperatures threaten to destabilize crucial ecosystems, underscoring the necessity of rigorous monitoring to assess their condition.

“Although our findings indicate that many northern ecosystems still function as sinks for carbon dioxide, regions that are sources of emissions, coupled with the prevalence of wildfires, are significantly undermining the net carbon uptake and reversing trends established over long periods,” explains ecologist Anna Virkkala from Woodwell Climate.

A key component of this dynamic is wildfire activity; the researchers found that wildfires are not only growing more frequent but also increasingly impactful in the ABZ. While wildfires are considered, it becomes evident that 40 percent of the ABZ emitted more CO₂ than it absorbed from 2001 to 2020, in contrast to 34 percent when excluding wildfire impacts.

The data, derived from meticulous compilation from 200 carbon monitoring stations within the ABC Flux network, underpin the findings. Seasonal variations are notable; during summer, the ABZ’s carbon sink capabilities peak due to enhanced vegetation and photosynthesis, whereas winter temperatures, which are atypically warm, expose more soil and organic matter, leading to increased CO₂ release.

“This variability is not unexpected as the Arctic encompasses vast areas with diverse climatic conditions and ecosystems,” remarks ecologist Sue Natali from Woodwell Climate. “We now possess the means to meticulously track and map carbon processes, providing insights into ground-level phenomena.”

Research conducted between 1990 and 2020 indicates a general strengthening of the ABZ’s role as a carbon sink, yet persistent hotspots, particularly in tundra ecosystems, show a contrary trend, a finding corroborated by previous studies. Nearly half of the planet’s soil-stored carbon is believed to reside in this region.

To comprehensively understand the ongoing transformations on our planet, it is imperative to monitor how various components of the ABZ function throughout the year and how a warming, rejuvenated Arctic may contribute to shifts in global atmospheric conditions.

“Collaborative efforts of this magnitude are essential for grasping the implications of altered seasonal dynamics and disturbance patterns, which may have repercussions at both regional and global scales,” states ecologist Marguerite Mauritz from the University of Texas-El Paso. The findings have been published in Nature Climate Change.