ARCTIC BOREAL ZONE BECOMES A CARBON SOURCE

GS3 SCIENCE AND TECH

Recent research reveals a concerning shift in the Arctic Boreal Zone, with nearly 40% of the region transitioning from a carbon sink to a carbon source. This change is largely driven by climate change, including longer growing seasons, increased microbial activity, and more frequent wildfires. The findings suggest that this transformation could significantly impact global climate regulation.

Carbon Sink vs. Carbon Source

• Carbon Sink: Absorbs more carbon dioxide than it releases.
• Carbon Source: Emits more carbon than it absorbs.

The Arctic, which was once a carbon sink, is now becoming a significant carbon source, contributing to global warming.

Research Findings A study published in Nature Climate Change analysed data from 200 monitoring sites between 1990 and 2020. It found that over 30% of the Arctic Boreal Zone is now a net carbon source, with fire emissions pushing this figure to 40%.

Geographical Distribution Carbon source areas are most prevalent in:

• Alaska: 44%
• Northern Europe: 25%
• Canada: 19%
• Siberia: 13%

These emissions are especially significant during the non-summer months, when carbon absorption is low.

Impact of Warming Temperatures Warming temperatures are causing permafrost to thaw, releasing vast amounts of stored carbon, which exacerbates climate change and turns the Arctic tundra into a carbon source.

Changes in Vegetation While the Arctic Boreal Zone has experienced “greening,” with 49% showing longer growing seasons, only 12% remains a net carbon sink annually, limiting its capacity to absorb carbon.

Boreal Forest Vulnerability Boreal forests in Canada, Alaska, and Siberia are warming four times faster than the global average. This rapid warming increases their vulnerability to wildfires, reducing their role as carbon sinks.

Tree Cover Dynamics A study from Wageningen University (2000-2020) found that warmer regions are seeing declines in dense tree cover (over 60%), while colder regions experience increases. By 2100, boreal forests are expected to stabilize with intermediate tree cover, ranging from 30-50% in warmer areas and 25-30% in colder areas.

Fire Risks and Ecosystem Changes Open forests are more prone to wildfires due to increased flammability, which may complicate predictions of fire behaviour and disrupt ecosystem dynamics. This shift could undermine the boreal biome’s ability to regulate the global climate effectively.