Example
Forests hold carbon in vegetation, soils and dead organic material.
The catch
A stock is different from the annual rate of uptake.
Related terms
Afforestation, Biodiversity, Blue carbon, Carbon sink, Deforestation, Ecosystem
In more depth
Carbon stock, explained.
A carbon stock shows how much carbon is at risk if an ecosystem is cleared, drained or burned. Peatland covers a small share of the world's land yet holds a disproportionate share of its soil carbon, and a drained bog can lose in decades what took millennia to accumulate. Stores like these cannot be rebuilt on any timescale that matters for current climate goals, which makes protecting them a priority.
Measuring a stock takes fieldwork. Surveyors record tree diameters and heights, convert them to biomass with standard equations, sample soils at set depths and, increasingly, check results with airborne laser scans. Figures may be stated as carbon or as CO₂, and the second is much larger for the same store. Protecting a stock produces avoided emissions, which differ from removals, so a claim should say which one it describes.