Carbon Flux Calculator

Carbon flux is a rate of carbon transfer between reservoirs, and ecosystem carbon accounting follows a strict hierarchy of nested terms. Gross primary production is total photosynthetic uptake; subtracting plant autotrophic respiration gives net primary production; subtracting heterotrophic respiration by soil microbes and decomposers gives net ecosystem production, which is positive when the ecosystem accumulates carbon. Net ecosystem exchange is the same quantity expressed with the atmospheric sign convention reversed, so NEE is negative during uptake. Net biome production goes further and subtracts non-biological losses such as fire, harvest, erosion, and dissolved leaching, making it the figure relevant to any long-term sequestration claim. Realistic magnitudes are worth holding in mind when entering values. Temperate forest net primary production is roughly 500 to 1,200 gC per square metre per year, tropical moist forest can exceed 2,000, and tundra falls below 200, so daily rates are on the order of 1 to 5 gC per square metre rather than hundreds. Soil respiration commonly accounts for 60 to 80 percent of total ecosystem respiration. Converting carbon mass to CO2 mass uses the factor 3.667, the ratio of molar masses 44 to 12. At global scale, fluxes are reported in petagrams of carbon per year, with recent Global Carbon Budget assessments placing fossil emissions near 10 PgC per year against land and ocean sinks of roughly 3 and 2.8 PgC per year. The dominant caveat is temporal: a single-day flux says very little, because ecosystems swing between sink and source seasonally and after drought or disturbance.

Continuous measurement of atmospheric carbon began with Charles David Keeling, whose CO2 record at Mauna Loa Observatory started in 1958 and produced the sawtooth curve showing both the seasonal breathing of Northern Hemisphere vegetation and a relentless annual rise. That curve turned the global carbon balance into a measurable quantity and prompted decades of work to identify which ecosystems were absorbing the carbon that emissions inventories could not account for. The conceptual vocabulary of net primary, net ecosystem, and net biome production was formalized through the International Biological Programme of the late 1960s and 1970s and refined in the ecological literature during the 1990s. Direct flux measurement rests on the eddy covariance technique, whose theoretical basis was set out by the Australian meteorologist W. C. Swinbank in 1951 but which became practical only when fast-response infrared gas analysers and sonic anemometers matured during the 1980s. Regional networks followed quickly: AmeriFlux and EUROFLUX began in the mid-1990s, and FLUXNET was organized in 1997 and 1998 to integrate them into a global archive now spanning hundreds of towers across most major biomes. The Global Carbon Project, launched in 2001, has published an annual global carbon budget ever since, and dedicated satellite missions, including NASA's Orbiting Carbon Observatory-2 in 2014, extended flux inference to regions where no towers exist.