Carbon is an essential element for life, but its behavior during Earth’s accretion is not well understood. Carbonaceous grains in meteoritic and cometary materials suggest that irreversible sublimation, and not condensation, governs carbon acquisition by terrestrial worlds. Through astronomical observations and modeling, we show that the sublimation front of carbon carriers in the solar nebula, or the soot line, moved inward quickly so that carbon-rich ingredients would be available for accretion at 1 astronomical unit after the first million years. On the other hand, geological constraints firmly establish a severe carbon deficit in Earth, requiring the destruction of inherited carbonaceous organics in the majority of its building blocks. The carbon-poor nature of Earth thus implies carbon loss in its precursor material through sublimation within the first million years.
Bibliographical noteFunding Information:
We thank L. Nittler and an anonymous reviewer for critically reading the manuscript and helping us improve and clarify it. Funding: This research was supported by NSF grants AST 1344133, EAR 1763189, and AST1907653 and by the NASA Astrobiology Program, grant NNX15AT33A. Author contributions: J.L., E.A.B., G.A.B., F.J.C., and M.M.H. contributed equally to the project design and writing. Competing interests: The authors declare that they have no competing interests. Data and materials availability: All data needed to evaluate the conclusions in the paper are present in the paper and/or the Supplementary Materials. Additional data related to this paper may be requested from the authors.
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