<P> The largest human impact on the carbon cycle is through direct emissions from burning fossil fuels, which transfers carbon from the geosphere into the atmosphere . The rest of this increase is caused mostly by changes in land - use, particularly deforestation . </P> <P> Another direct human impact on the carbon cycle is the chemical process of calcination of limestone for clinker production, which releases CO . Clinker is an industrial precursor of cement . </P> <P> Humans also influence the carbon cycle indirectly by changing the terrestrial and oceanic biosphere . Over the past several centuries, direct and indirect human - caused land use and land cover change (LUCC) has led to the loss of biodiversity, which lowers ecosystems' resilience to environmental stresses and decreases their ability to remove carbon from the atmosphere . More directly, it often leads to the release of carbon from terrestrial ecosystems into the atmosphere . Deforestation for agricultural purposes removes forests, which hold large amounts of carbon, and replaces them, generally with agricultural or urban areas . Both of these replacement land cover types store comparatively small amounts of carbon, so that the net product of the process is that more carbon stays in the atmosphere . </P> <P> Other human - caused changes to the environment change ecosystems' productivity and their ability to remove carbon from the atmosphere . Air pollution, for example, damages plants and soils, while many agricultural and land use practices lead to higher erosion rates, washing carbon out of soils and decreasing plant productivity . </P>

Where is the largest quantity of inorganic carbon found