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Why can wildfires and decomposition release stored carbon back into the atmosphere?

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Illustration of various geoengineering techniques to address climate change, including carbon capture and storage methods like artificial trees, industrial scrubbers, and deep ocean CO2 storage, as well as solar reflectance strategies such as sulfur aerosols, reflective crops, cloud whitening, and orbital mirrors. The scene shows these interventions applied to land, sea, and atmosphere, with labeled features explaining each process. — Geoengineering Various geoengineering proposals designed to increase solar reflectance or capture and store carbon.

Wildfires and decomposition release stored carbon back into the atmosphere because they reverse the natural process of carbon sequestration, which is the capture and storage of carbon dioxide by living vegetation and soil.12

Decomposition: As plants and other terrestrial vegetation die, they undergo decomposition, a process where microorganisms break down organic matter. During this cycle, the carbon that these organisms sequestered throughout their lifetimes is released back into the atmosphere as carbon dioxide (CO₂). In soil, this release is known as soil respiration, which is a vital part of the natural carbon cycle.13
Wildfires: Fires act as a rapid mechanism for releasing carbon. When vegetation burns, the carbon stored in its biomass is emitted directly into the atmosphere as CO₂.4

These processes are significant in Earth science because they can create positive feedback loops; for example, climate warming can increase the frequency of wildfires and accelerate the decomposition of organic matter in soil and permafrost, leading to further atmospheric carbon increases and additional warming.4