Earth's Core May Harbor Largest Reservoir of Carbon on Our Planet

Where is most of Earth's carbon located? It turns out that the majority of it can be found within our planet's inner core. This makes the core into the largest carbon reservoir on our planet, according to the new model created by scientists.

It is now widely accepted that Earth's inner core consists of crystalline iron alloyed with a small amount of nickel and some lighter elements. However, seismic waves-called S waves-travel through the inner core at about half the speed expected for most iron-rich alloys under relevant pressures. Some scientists have attributed these S-wave velocities to the presence of liquid, which calls into question whether the inner core is actually solid. In addition, in recent years the presence of various light elements has been proposed to account for the density deficit in Earth's core.

In recent years, iron carbide has emerged as a leading candidate component of the inner core. In fact, this could help explain the slow S waves, and eliminates the need to explain the slower waves through partial melting.

"The model of a carbide inner core is compatible with existing cosmochemical, geochemical and petrological constraints, but this provocative and speculative hypothesis still requires further testing," said Jie Li, the principal investigator of the project, in a news release. "Should it hold up to various tests, the model would imply that as much as two-thirds of the planet's carbon is hidden in its center sphere, making it the largest reservoir of carbon on Earth."

The findings reveal that the Earth's core may be a bit different from previous models. Instead, it could hold a vast reservoir of carbon. That said, scientists need to conduct further experimentation before any firm conclusions are drawn.

The findings are published in the journal Proceedings of the National Academy of Sciences.

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