Multi-scale processes influencing global carbon storage and land-carbon-climate nexus: A critical review

Carbon (C) is a key constitutive element in living organisms (plants, microbes, animals, and humans). Carbon is also a basic component of agriculture because it plays a dynamic role in crop growth, development, nutrient cycling, soil fertility, and other agricultural features. The presence of C enhances soil physical, chemical, and biological properties. The C cycle supports all life on the Earth by transferring C between living organisms and the environment. The global climate is changing, and this change is attributable to the release of carbon dioxide and other greenhouse gases from human activities. Owing to the global climate change, agriculture is expected to be majorly affected. Agricultural production is directly linked to the climate. The five main global C pools are the oceanic, geologic, pedologic, atmospheric, and biotic pools, with specific reservoirs and inter-pool fluxes. The soil organic matter has various organic C pools (active, slow, and passive pools), containing various C-based fractions and specific liability pools. Climate, geology, land use, and management techniques are some of the variables that affect organic C and its reservoirs. The dynamics of each of these variables must be understood for a thorough knowledge of how they impact the soil C pools and storage capacity under the changing climate conditions. This review provides a comprehensive overview of the various factors that affect soil C pools/fractions and their C sequestration capacity.