≈550 gigatons of carbon (Gt C)
||Bar-On YM, Phillips R, Milo R. The biomass distribution on Earth. Proc Natl Acad Sci U S A. 2018 Jun 19 115(25):6506-6511. doi: 10.1073/pnas.1711842115 abstract, p.2 left column and table 1PubMed ID29784790
||P.1 right column 3rd paragraph: "The Biomass Distribution of the Biosphere by Kingdom: In Fig. 1 and Table 1, [investigators] report [their] best estimates for the biomass of each taxon analyzed. [They] use biomass as a measure of abundance, which allows [them] to compare taxa whose members are of very different sizes. Biomass is also a useful metric for quantifying stocks of elements sequestered in living organisms. [They] report biomass using the mass of carbon, as this measure is independent of water content and has been used extensively in the literature (refs 6, 16, 17)." P.4 right column 3rd paragraph: "In Table 1, [investigators] detail the relevant supplementary table that summarizes the steps for arriving at each estimate. All of the data used to generate [their] estimates, as well as the code used for analysis, are open-sourced and available at link ."
||Abstract: "A census of the biomass on Earth is key for understanding the
structure and dynamics of the biosphere. However, a global,
quantitative view of how the biomass of different taxa compare with one another is still lacking. Here, [investigators] assemble the overall biomass composition of the biosphere, establishing a census of the
≈550 gigatons of carbon (Gt C) of biomass distributed among all of
the kingdoms of life." P.2 left column: "The sum of the biomass across all taxa on Earth is ≈550 Gt C, of which ≈80% (≈450 Gt C, SI Appendix, Table S2) are plants, dominated by land plants (embryophytes)."