Terrestrial carbon cycle: tipping edge of climate change between the atmosphere and biosphere ecosystems

Abstract

Owing to its tendency to couple with multiple elements, carbon forms complex molecules, which is the basic chemistry of life. Given that the climate system is inextricably coupled with the biosphere, understanding the terrestrial mechanistic pathway of carbon is critical in the transformation of the augmenting atmospheric carbon dioxide (CO₂) in future. Although the global terrestrial carbon sink reduces the accumulation of atmospheric CO₂, which is contingent on the climate and ecosystem, the underlying key biophysical function that controls the ecosystem-carbon-climate responses and their feedback is uncertain. Accordingly, numerous unprecedented multi-scale studies have highlighted the dynamics of terrestrial carbon by strategically employing in situ, earth observation and process-based models; however, to date, the driving force for its dynamics remains unclassified. Besides, the significant variability in carbon is related to the large uncertainties from changes in land use, unambiguously increasing the regional carbon source from the seasonal to interannual scale but without long-term positive or negative feedback. Accordingly, in this review, we attempt to present a holistic understanding of the terrestrial carbon cycle by addressing its nature and different key drivers. The heterogenetic data platforms that reliably address the terrestrial carbon sink and its source dynamics are discussed in detail to demonstrate the potential of systematic quantification. Moreover, we summarize the complexity of carbon-climate feedbacks and their associates, extending the pathway for understanding the recent terrestrial carbon allocation, where India's environment is highlighted. This comprehensive review can be valuable to the research community in understanding the importance of the present and future carbon-climate feedback.