Which greenhouse gas is released when forests are cleared and burned?

The greenhouse gas released when forests are cleared and burned is carbon dioxide.

Trees and other vegetation store carbon in their trunks, branches, leaves, roots, and surrounding soils. When forests are burned to clear land, much of that carbon is rapidly oxidized and released as CO₂. Carbon also enters the atmosphere more gradually when leftover plant material and disturbed soil decompose after clearing.

Deforestation creates a double climate effect: it releases greenhouse gases and removes trees that would otherwise absorb carbon dioxide through photosynthesis. Land-use change, especially deforestation, is therefore a major source of human-caused CO₂ emissions. Burning can also produce smaller or context-dependent amounts of other gases and particles, but carbon dioxide is the standard single answer for this question.

The word “released” does not mean forests produce only emissions. Growing forests can act as carbon sinks, taking in more CO₂ than they emit for a time. Their climate influence also includes changes to rainfall, surface reflectivity, and local temperature, so the full effect of forest loss extends beyond the combustion itself.