Carbon reservoirs and fluxes

Scientists model the carbon cycle with numbers, as reservoirs, places where carbon is stored, connected by fluxes, the rates at which carbon moves between them, measured in gigatonnes of carbon (GtC; one gigatonne is a billion metric tons). By far the largest reservoir is rock, especially limestone and other carbonate rocks and organic carbon in shale, holding tens of millions of gigatonnes. The deep ocean holds about 37,000 GtC, soils and permafrost a few thousand, living vegetation about 450 to 650, and the atmosphere about 900 GtC today, up from about 590 before industrialization. In the fast carbon cycle, large fluxes, up to more than 100 GtC per year, move each way between the atmosphere and plants through photosynthesis and respiration, and between the atmosphere and the ocean surface. In the slow carbon cycle, the weathering of rock, the burial of carbon in sediments, and volcanic outgassing move far smaller amounts, well under 1 GtC per year, over millions of years. Burning fossil fuels and making cement now release about 10 GtC per year, moving carbon from the slow cycle into the fast cycle, and clearing forests adds about 1 more. Of this, roughly half stays in the atmosphere, about a quarter dissolves in the ocean, and about a quarter is taken up by land plants and soils. Life has reshaped this cycle throughout Earth's history, from early photosynthesis drawing down carbon dioxide to ancient swamp forests forming coal.

This explanation is AI-generated and can occasionally be wrong. 🚩 Report