Total carbon

The global map of above- and below-ground terrestrial carbon storage (tonnes (t) of C per km²) merges the following layers: (i) the above-ground carbon, expressed in tonnes of carbon per km² which corresponds to the carbon fraction of the oven-dry weight of the woody parts (stem, bark, branches and twigs) of all living trees, excluding stump and roots, as estimated by the GlobBiomass project (globbiomass.org) with 2017 as the reference year (Santoro et al., 2019), and (ii) the belowground biomass carbon (BBC), expressed in tonnes of carbon per km² which represents an estimation of the carbon stored in the roots of all living trees. The BBC is a derived product from two main sources of information: (i) above-ground biomass (AGB) data provided by the global terrestrial biomass map derived from Earth Observation data in the framework of the GlobBiomass project, and (ii) chapter 4 of the 2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories (IPCC, 2019), which indicates the most updated root-to-shoot ratios (R). The IPCC Root-to-shoot ratios depend on the biogeographic conditions (ecozone), forest type, forest origin (natural or planted) and aboveground biomass density (Table 4.4 of IPCC, 2019). However, while the biomass map provides wall-to-wall global coverage, the IPCC ratios are not available for all existing combinations of the parameters indicated above.