Carbon content of Earth’s core

Researchers report estimates of the carbon content in Earth’s core. The total amount of Earth’s carbon–the bulk carbon content–is poorly understood due to uncertainty in the amount of carbon in Earth’s core, where most carbon is likely located. To better estimate the carbon content of Earth’s core, Rebecca Fischer and colleagues measured the preference of carbon for mixing with iron and nickel, which represents the composition of the core, over a silicate mineral, such as those found in Earth’s mantle. The authors performed the measurements at pressures of 37-59 GPa and temperatures of 4200-5200 K, approximating the conditions under which Earth’s core formed. Under these conditions, the preference of carbon for iron and nickel was two orders of magnitude lower than that measured in previous studies at more modest temperatures and pressures. Combining the results with previously published values of the carbon content of the mantle, the authors estimated that carbon constitutes a miniscule fraction of Earth’s core: 66-220 ppm, assuming the core formed in a single stage, or 0.09-0.2 wt% based on a model of multi-stage core formation. However, this small fraction of the core nevertheless represents approximately 80-90% of Earth’s bulk carbon content, according to the authors.

Article #19-19930: “The carbon content of Earth and its core,” by Rebecca A. Fischer, Elizabeth Cottrell, Erik H. Hauri, Kanani K. M. Lee, and Marion Le Voyer.

MEDIA CONTACT: Rebecca A. Fischer, Harvard University, Cambridge, MA; tel: 913-820-0571; e-mail:

[email protected]

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