explain how carbon is transferred back and forth between the atmosphere and forests.

June 28, 2026

Carbon moves between the atmosphere and forests in a continuous loop driven mainly by photosynthesis, respiration, decomposition, and disturbances like fire or logging. Forests act as both a store of carbon and a source, depending on whether growth or decay and disturbance dominate at a given time.

Into forests from air

Trees absorb carbon dioxide (CO₂) from the atmosphere during photosynthesis and turn it into sugars and wood. This carbon is stored in trunks, branches, leaves, roots, dead wood, and forest soils.

Over decades to centuries, large forests can build up very big carbon stocks in both vegetation and soil, making them important carbon “sinks” when growth exceeds losses.

Back to air from forests

Plants respire day and night, releasing some CO₂ back to the atmosphere as they use stored sugars for energy.

When trees and other plants die, microbes and fungi decompose the dead material, breaking down wood, leaves, and roots and releasing CO₂ (and sometimes methane) as they respire.

Disturbances and rapid release

Wildfires, insect outbreaks, storms, and human activities like clear-cutting or burning forest land can rapidly release large amounts of carbon that had been stored, turning forests from sinks into net sources of CO₂.

After such disturbances, regrowing forests usually switch back to taking up more carbon than they release as young trees grow quickly and rebuild biomass and soil carbon.

Forest soils and long-term storage

Part of the carbon from fallen leaves, roots, and dead wood becomes stable organic matter in soils, where it can remain locked away for decades to centuries or longer.

The balance between carbon that is decomposed and returned to the air versus carbon that becomes stable soil organic matter strongly controls how much forests offset atmospheric CO₂ over the long term.

Human influence today

When forests are conserved or managed to maintain or increase biomass and soil carbon, they help offset a portion of human CO₂ emissions by acting as net carbon sinks.

When forests are cleared, degraded, or burned and not allowed to regrow, stored carbon is released and the forest’s capacity to pull CO₂ from the atmosphere is reduced, reinforcing climate change.

Information gathered from public forums or data available on the internet and portrayed here.