Hiilivarannot

Hiilivarannot is a Finnish term used in climate science and environmental policy to describe carbon stocks or reservoirs across natural and human-made systems. The concept covers carbon stored in living biomass (forests, vegetation), soils and peatlands, and the oceans, as well as geological reservoirs that contain fossil carbon such as coal, oil, and natural gas. In some contexts it also includes managed carbon stores, for example soil carbon enhancement through land management or biochar. A key distinction is between the amount of carbon present in a reservoir at a given time (the stock) and the flows that add to or subtract from it (the flux).

Global hiilivarannot are central to the carbon cycle and climate budgets. The oceans are the largest natural reservoir, followed by terrestrial ecosystems and soils; peatlands and permafrost contain substantial amounts that are vulnerable to warming. Geological reservoirs hold the most carbon in total, but it remains largely inaccessible or unutilized unless exploited as fossil fuels. In policy and planning, estimates of hiilivarannot underpin carbon accounting, land-use strategies, and mitigation approaches such as afforestation, soil carbon sequestration, and the sustainable management of forests, wetlands, and coastal systems.

Measurement and estimation rely on a combination of remote sensing, ground inventories, soil surveys, and climate models. Uncertainties are substantial, particularly for soil carbon and deep-ocean stocks, and potential climate feedbacks could alter reservoir sizes over time. As such, hiilivarannot are continually refined to support robust climate targets and policy decisions.

See also: carbon cycle, carbon sink, carbon budget, fossil fuel reserves.