How does the decay or burning of peat contribute to the release of carbon dioxide into the atmosphere?

Sourav PanNovember 12, 2024

Answered

The decay or burning of peat contributes to the release of carbon dioxide (CO₂) into the atmosphere through several mechanisms related to the unique characteristics of peatlands and the processes involved in carbon storage and release. Here’s how these processes work:

1. Peat Composition and Carbon Storage

• Carbon Accumulation: Peatlands are formed from partially decomposed plant material that accumulates over thousands of years in waterlogged conditions. This anaerobic environment slows down decomposition, allowing carbon to accumulate in the form of peat. Peatlands store a significant amount of carbon—estimated to be around 68.5 petagrams globally, which is more than double the carbon stored in all forests combined.

2. Decay of Peat

• Aerobic Decomposition: When peatlands are drained for agriculture or development, the water level decreases, exposing peat to oxygen. This exposure accelerates aerobic decomposition, where microorganisms break down organic matter more rapidly than in saturated conditions. As a result, carbon that was previously stored in the peat is released back into the atmosphere as CO₂. Estimates suggest that drained peatlands can emit between 355 and 874 million tonnes of CO₂ annually due to this decomposition process.

3. Burning of Peat

• Peat Fires: When peatlands are drained, they become more susceptible to fires, which can burn both surface vegetation and the underlying peat. Peat fires are particularly damaging because they can smolder underground for extended periods, releasing significant amounts of CO₂ and other greenhouse gases (GHGs) such as methane (CH₄) and nitrous oxide (N₂O). Studies indicate that peat fires can contribute to 40% to 60% of total greenhouse gas emissions from deforestation fires in regions like Southeast Asia.
• High Emission Rates: The emissions from peat fires can be substantial; for example, fires in drained peatlands in Southeast Asia alone account for approximately 8% of global CO₂ emissions from fossil fuel burning . The slow-burning nature of these fires means they can release carbon over an extended period, exacerbating their impact on climate change.

4. Climate Feedback Mechanisms

• Increased Temperature and Decomposition Rates: Warmer temperatures associated with climate change can further accelerate the decomposition of organic material in peatlands, leading to increased CO₂ emissions. As soils warm, microbial activity increases, resulting in faster breakdown of organic matter and more carbon being released into the atmosphere .
• Hydrological Changes: Changes in precipitation patterns can also affect water levels in peatlands, influencing their ability to store carbon. Drier conditions may lead to increased oxidation and decomposition rates, further contributing to CO₂ emissions