5.18—Carbon cycle applications

Atmospheric carbon dioxide falls only when removal from the atmosphere exceeds additions over the relevant time period. Carbon sinks include forests, soils, peat and oceans, while combustion and land-use change add carbon.

Protecting or restoring a sink changes a flow or storage; it does not make emissions disappear. A strategy should be judged by permanence, scale, leakage and whether it reduces the net atmospheric increase.

Reforestation can increase carbon stored in biomass and soil, but drought, fire or later clearing can return carbon to the atmosphere. Cutting fossil-fuel combustion reduces the source flow directly.

“Carbon neutral” is not automatically permanent removal, and a local increase in biomass does not prove a global atmospheric decline. Track the stock–flow balance.