This event will be held remotely over Zoom.
Title: Tropical Forests Control Atmospheric CO 2 Growth Rate
Abstract: Year-to-year variations in the atmospheric CO 2 growth rate (CGR) have been attributed mostly to the fluctuation of the carbon uptake by the terrestrial biosphere. However, how and which terrestrial ecosystems contribute to CGR variability remain unresolved. Using data from ground inventory, air, and satellite observations, we develop annual (2000-2019) estimates of global live vegetation biomass carbon stock at landscape scales and quantify the interannual variability (IAV) of emissions and removals of carbon from fire and forest clearings. We show that on average the carbon loss of attributed to wildfires and forest clearing in this century is compensated by the carbon gain of from recovery of vegetation from past disturbances. However, carbon fluxes exhibit different patterns at continental and regional scales. Among ecosystems, tropical forests remain the largest component of the terrestrial carbon sources and sinks, with tropical Americas loosing carbon on the average, while tropical Africa gaining carbon, and tropical Asia remaining net neutral or losing carbon intermittently. We find that emissions from vegetation either from land use or climate disturbances have almost no impacts on the IAV of the global atmospheric CO 2 growth rate. It is however, the post-disturbance recovery (carbon uptake) of vegetation that controls almost all the entire IAV of CGR, with tropics explaining 80% and extra-tropics the remaining 20% of IAV. Our results suggest that although the temperate and boreal ecosystems remain a steady carbon sink over the 21 st Century, tropical forests may play the dominant role in the climate mitigation policies of the post-2020 Paris agreement.