Bar-On Lab

Terrestrial sequestration of carbon has mitigated approximate to 30% of anthropogenic carbon emissions. However, its distribution across different pools, live or dead biomass and soil and sedimentary organic carbon, remains uncertain. Analyzing global observational datasets of changes in terrestrial carbon pools, we found that approximate to 35 +/- 14 gigatons of carbon (GtC) have been sequestered on land between 1992 and 2019, whereas live biomass changed by approximate to 1 +/- 7 GtC. Global vegetation models instead imply that sequestration has been mostly in live biomass. We identify key processes not included in most models that can explain this discrepancy. Most terrestrial carbon gains are sequestered as nonliving matter and thus are more persistent than previously appreciated, with a substantial fraction linked to human activities such as river damming, wood harvest, and garbage disposal in landfills.

Insects and other arthropods are central to terrestrial ecosystems. However, data are lacking regarding their global population abundance. We synthesized thousands of evaluations from around 500 sites worldwide, estimating the absolute biomass and abundance of terrestrial arthropods across different taxa and habitats. We found that there are approximate to 1 x 10(19) (twofold uncertainty range) soil arthropods on Earth, approximate to 95% of which are soil mites and springtails. The soil contains approximate to 200 (twofold uncertainty range) million metric tons (Mt) of dry biomass. Termites contribute approximate to 40% of the soil biomass, much more than ants at approximate to 10%. Our estimate for the global biomass of above-ground arthropods is more uncertain, highlighting a knowledge gap that future research should aim to close. We estimate the combined dry biomass of all terrestrial arthropods at approximate to 300 Mt (uncertainty range, 100 to 500), similar to the mass of humanity and its livestock. These estimates enhance the quantitative understanding of arthropods in terrestrial ecosystems and provide an initial holistic benchmark on their decline.

Obtaining a quantitative global picture of life in the great expanses of the oceans is a challenging task. By integrating data from across existing literature, we provide a comprehensive view of the distribution of marine biomass between taxonomic groups, modes of life, and habitats.

Photosynthetic carbon assimilation enables energy storage in the living world and produces most of the biomass in the biosphere. Rubisco (D-ribulose 1,5-bisphosphate carboxylase/oxygenase) is responsible for the vast majority of global carbon fixation and has been claimed to be the most abundant protein on Earth. Here we provide an updated and rigorous estimate for the total mass of Rubisco on Earth, concluding it is approximate to 0.7 Gt, more than an order of magnitude higher than previously thought. We find that > 90% of Rubisco enzymes are found in the approximate to 2 x 10(14) m(2) of leaves of terrestrial plants, and that Rubisco accounts for approximate to 3% of the total mass of leaves, which we estimate at approximate to 30 Gt dry weight. We use our estimate for the total mass of Rubisco to derive the effective time-averaged catalytic rate of Rubisco of approximate to 0.03 s(-1) on land and approximate to 0.6 s(-1) in the ocean. Compared with the maximal catalytic rate observed in vitro at 25 degrees C, the effective rate in the wild is approximate to 100-fold slower on land and sevenfold slower in the ocean. The lower ambient temperature, and Rubisco not working at night, can explain most of the difference from laboratory conditions in the ocean but not on land, where quantification of many more factors on a global scale is needed. Our analysis helps sharpen the dramatic difference between laboratory and wild environments and between the terrestrial and marine environments.

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, we 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. We find that the kingdoms of life concentrate at different locations on the planet; plants (≈450 Gt C, the dominant kingdom) are primarily terrestrial, whereas animals (≈2 Gt C) are mainly marine, and bacteria (≈70 Gt C) and archaea (≈7 Gt C) are predominantly located in deep subsurface environments. We show that terrestrial biomass is about two orders of magnitude higher than marine biomass and estimate a total of ≈6 Gt C of marine biota, doubling the previous estimated quantity. Our analysis reveals that the global marine biomass pyramid contains more consumers than producers, thus increasing the scope of previous observations on inverse food pyramids. Finally, we highlight that the mass of humans is an order of magnitude higher than that of all wild mammals combined and report the historical impact of humanity on the global biomass of prominent taxa, including mammals, fish, and plants.