Contrasting sensitivities and vulnerabilities of terrestrial biosphere carbon cycle to climate anomalies across tropical south America

Abstract:

The forests over tropical South America have been estimated to have ~95-120 GtC in living biomass and additional ~160 GtC in soils. In total, its carbon storage is equivalent to ~one third of the carbon stored in the atmosphere. Thus, any small perturbations and trend in the carbon dynamics over the region would have significant implications for the global carbon budget, and understanding its carbon dynamics as a function of climate is essential for future carbon-climate projections. Within tropical South America, the northwest features wetter and cloudy climate throughout the year, with annual total precipitation exceeding 2000mm, while the east and south feature more seasonal climate. Previous studies have shown that the carbon-climate sensitivity could be a function of local mean climate itself. In this study, with net biosphere carbon exchanges (NBE) estimated from multiple inversion systems and its component fluxes including gross primary production and biomass burning, we aim to quantify sub-regional carbon-climate sensitivities, especially contrasting the carbon-climate sensitivities between the east and the west of tropical south America. We will further explore the mechanisms that diverse the contrasting carbon-climate sensitivities within tropical South America with a data-assimilation framework CARDAMOM that assimilates NBE and its component fluxes. At last, we will compare to observation constrained carbon-climate sensitivities to dynamical global vegetation model simulations and discuss the implications for future carbon-climate feedback projections.