Remobilization of crustal carbon may dominate volcanic arc emissions

The flux of carbon into and out of Earth’s surface environment has implications for Earth’s climate and habitability. We compiled a global data set for carbon and helium isotopes from volcanic arcs and demonstrated that the carbon isotope composition of mean global volcanic gas is considerably heavier, at –3.8 to –4.6 per mil (), than the canonical mid-ocean ridge basalt value of –6.0. The largest volcanic emitters outgas carbon with higher 13C and are located in ma