Arctic Tundra: From Carbon Sink to Source

Arctic tundra, a frozen treeless biome which has stored carbon for thousands of years, has now become a source of heat-trapping greenhouse gases (GHGs) as per the analysis, ‘Arctic Report Card.

About Arctic tundra

• The Arctic tundra is a cold, desert-like biome that surrounds the North Pole and extends south into the taiga, or boreal forest: 
• Location: Found in the northern hemisphere, stretching across North America, Europe, and Asia. 
• Climate: It is the coldest biome on Earth, with average winter temperatures of -34° C (-30° F) and average summer temperatures of 3-12° C. 
  • The growing season is short, lasting only 50 to 60 days. 
• Precipitation: It receives low amounts of precipitation, with yearly precipitation of 15 to 25 cm (6 to 10 inches). 
• Soil: Permanently frozen subsoil called permafrost, which is made up of gravel and finer material.   
• Vegetation: Variety of plants that can survive the cold climate, including mosses, lichens, herbs, and dwarf shrubs. 
• Fauna: Home to many animals, including herbivores like lemmings, voles, caribou, arctic hares, and squirrels, and carnivores like arctic foxes, wolves, and polar bears.

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How Does the Arctic Tundra Store Carbon?

• Carbon Cycle: In a typical ecosystem, plants absorb carbon dioxide (CO₂) from the atmosphere through the process of photosynthesis. 
  • When these plants and animals die, microorganisms such as bacteria and fungi decompose the organic matter, returning CO₂ to the atmosphere. This completes the carbon cycle.
• Slow decomposition: However, in the Arctic tundra, the cold climate dramatically slows down the decomposition process. 
• Trap in ice: Organic remains of plants and animals become trapped in permafrost, which refers to any ground that stays frozen for at least two consecutive years. 
• No release back: Because of the freezing temperatures, the CO₂ stored in organic matter is not released back into the atmosphere.
• Storage: Scientists estimate that Arctic soils store 1.6 trillion metric tonnes of carbon, which is approximately double the amount of carbon present in the atmosphere.

Why is the Arctic Tundra Emitting Carbon?

• Rising Temperatures: The Arctic is currently warming at four times the global rate. 
  • According to the report, the annual surface air temperatures in 2024 were the second-warmest on record since 1900. 
  • As a result, the permafrost in the region is thawing. 
    • When permafrost thaws, microbes in the soil become active and start decomposing the organic matter trapped in the frozen ground. 
    • This process releases carbon dioxide (CO₂) and methane (CH₄), which are potent greenhouse gases. 
  • Thawing permafrost behaves like frozen chicken. 
    • As long as the chicken remains frozen, microbes cannot act on it. However, once thawed, microbes break it down, leading to decomposition. 
    • The permafrost follows a similar process, releasing stored carbon.
• Increase in Wildfires: In recent years, the Arctic has experienced an increase in the frequency and intensity of wildfires. 
  • The year 2023 recorded the worst wildfire season in the Arctic, while 2024 was the second-worst year for wildfire emissions.
  • Wildfire smoke contributes to greenhouse gas emissions while also accelerating the thawing of permafrost. 

Global Consequences

• Impact: The combined impact of wildfires and rising temperatures caused the Arctic tundra to release more carbon than it absorbed between 2001 and 2020. 
  • This is likely the first time such a transformation has occurred in thousands of years.
• Carbon Emission: If the Arctic tundra continues to emit more carbon than it absorbs, it will have significant global consequences. 
  • The emissions of CO₂ and CH₄ will further amplify global warming, accelerating the adverse impacts of climate change worldwide.

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Way Forward

• Reduce global greenhouse gas (GHG) emissions to reverse Arctic emissions.
• Lower GHG levels will result in reduced emissions from thawing permafrost, helping to restore the Arctic tundra’s role as a carbon sink.
• Aggressive emissions reduction is essential to mitigate climate change.