Arctic Boreal Zone (ABZ)

In early 2025, multiple regions across the world — from Texas and California in the United States to Ofunato in Japan — witnessed devastating wildfires. These fires were not only destructive in scale but also released massive amounts of carbon dioxide into the atmosphere. Now, a new study has confirmed that over 30 percent of the Arctic Boreal Zone (ABZ) — previously a major carbon sink — has begun releasing more carbon than it absorbs, turning it into a net carbon source.

Key Findings of the Study

• Between 2001 and 2020, the Arctic region absorbed carbon dioxide during summer months. But this absorption was cancelled out by rising emissions during the colder seasons.
• As a result, one-third of the ABZ has shifted from being a carbon sink to a carbon source.
• Alaska alone accounts for 44 percent of the net emissions, while Siberia and northern Europe contribute 13 and 25 percent, respectively.
• The carbon released during longer non-summer periods (due to thawing and fires) is now exceeding the amount absorbed during the brief growing season.

The study also cites two key historical fire events — Russia’s Eastern Siberia fire in 2003 and Canada’s Timmins fire in 2012 — as critical moments when emissions overwhelmed the region’s carbon sequestration capacity.

 What is the Arctic Boreal Zone (ABZ)?

• Arctic Boreal Zone (ABZ) spans the northern latitudes across Alaska, Canada, Siberia, and Scandinavia.
• It includes tundra, coniferous (taiga) forests, permafrost, and wetlands.
• It is the largest terrestrial carbon sink on Earth, having stored massive amounts of organic carbon for centuries in frozen soils and plant biomass.
• Significance:
  • The ABZ stores carbon in permafrost, which is permanently frozen ground composed of decomposed organic matter.
  • It absorbs atmospheric carbon dioxide during brief summer periods, when plant growth is active.
  • Its frozen state ensures slow decomposition, preventing large-scale carbon release.

Why Has It Become a Carbon Source?

• Thawing of Permafrost: As global temperatures rise, permafrost is melting, exposing organic material to decomposition. This decomposition releases carbon dioxide and methane, both greenhouse gases.
• Increased Wildfires: More frequent and intense wildfires destroy vegetation and peat layers, reducing the region’s carbon-absorbing ability and releasing previously stored carbon.
• Changing Vegetation and Soil Moisture: Arctic warming is altering plant types, with fire-prone or less carbon-efficient vegetation replacing older species.
• Longer Warm Seasons and Shorter Winters: The ABZ is experiencing longer non-summer seasons with higher temperatures, leading to year-round carbon release. These emissions now exceed the summer gains, pushing the biome into a net emission status.

Relevance to India

• Indian Forest Fires: According to the India State of Forest Report 2024, over 5,300 fires were recorded in Uttarakhand alone. Forest fires in India already contribute around 69 million tonnes of CO? annually.
• Rising Land Temperatures: Indian regions like the northwest and central India are warming by 2–0.4°C per decade.
• Climatic Risk: India’s agriculture, water systems, and monsoons are highly sensitive to global climate feedbacks, making Arctic emissions a critical external factor.